# Dokumentasi Django 4.2.9.dev20231204082947

# Acuan bidang model

Dokumen ini mengandung semua acuan API dari `Field` termasuk field options dan field types Django tawarkan.

Lihat juga

Jika bidang-bidang siap-pakai tidak melakukan muslihat, anda dapat mencoba django-localflavor (documentation), yang mengandung bermacam-macam potongan dari kode yang berguna untuk negara dan budaya tertentu.

Juga, anda dapat dengan mudah write your own custom model fields.

Catatan

Secara teknis, model-mdoel ini ditentukan dalam `django.db.models.fields`, tetapi untuk kenyamanan mereka diimpor kedalam `django.db.models`; kebiasaan standar adalah menggunakan `from django.db import models` dan mengacu ke bidang-bidang sebagai `models.<Foo>Field`.

## Pilihan bidang

Argumen berikut tersedia pada semua jenis bidang. Semua adalah pilihan.

### `null`

`Field.``null`

Jika `True`, Django akan menyimpan nilai-nilai kosong sebagai `NULL` di basisdata. Awalan adalah `False`.

Hindari menggunakan `null` pada bidang-bidang berdasarkan-string seperti `CharField` dan `TextField`. Jika bidang berdasarkan-string mempunyai `null=True`, itu berarti mempunyai dua kemungkinan nilai untuk "no data": `NULL`, dan string kosong. Dalam kebanyakan kasus, itu berulang untuk memiliki dua kemungkinan nilai untuk "no data;" Kebiasaan Django adalah menggunakan string kosong, bukan `NULL`. Satu pengecualian adalah ketika `CharField` mempunyai `unique=True` dan `blank=True` disetel. Dalam keadaan ini, `null=True` adalah diwajibkan untuk menghindari pelanggaran batasan unik ketika menyimpan banyak obyek dengan nilai kosong.

Untuk kedua bidang berdasarkan-string dan bukan-berdasarkan-string, anda juga akan butuh mensetel `blank=True` jika anda berharap mengizinkan nilai kosong dalam formulir, sebagai parameter `null` hanya mempengaruhi penyimpanan basisdata (lihat `blank`).

Catatan

Ketika menggunakan backend basisdata Oracle, nilai `NULL` akan disimpan untuk menyatakan string kosong meskipun dari atribut ini.

### `blank`

`Field.``blank`

Jika `True`, bidang diizinkan menjadi kosong. Awalan adalah `False`.

Catat bahwa ini berbeda dari `null`. `null` murni hubungan-basisdata, dimana `blank` adalah hubungan-pengesahan. Jika sebuah bidang mempunyai `blank=True`, pengesahan formulir akan mengizinkan masukan dari sebuah nilai kosong. Jika sebuah bidang mempunyai `blank=False`, bidang akan diwajibkan.

Supplying missing values

`blank=True` can be used with fields having `null=False`, but this will require implementing `clean()` on the model in order to programmatically supply any missing values.

### `choices`

`Field.``choices`

A sequence consisting itself of iterables of exactly two items (e.g. `[(A, B), (A, B) ...]`) to use as choices for this field. If choices are given, they're enforced by model validation and the default form widget will be a select box with these choices instead of the standard text field.

Unsur pertama dalam setiap tuple adalah nilai sebenarnya untuk disetel pada model, dan unsur kedua adalah nama dapat-dibaca-manusia. Sebagai contoh:

    YEAR_IN_SCHOOL_CHOICES = [
        ("FR", "Freshman"),
        ("SO", "Sophomore"),
        ("JR", "Junior"),
        ("SR", "Senior"),
        ("GR", "Graduate"),
    ]

Umumnya, itu adalah terbaik menentukan pilihan didalam kelas model, dan menentukan ketetapan bernama-cocok untuk setiap nilai:

    from django.db import models

    class Student(models.Model):
        FRESHMAN = "FR"
        SOPHOMORE = "SO"
        JUNIOR = "JR"
        SENIOR = "SR"
        GRADUATE = "GR"
        YEAR_IN_SCHOOL_CHOICES = [
            (FRESHMAN, "Freshman"),
            (SOPHOMORE, "Sophomore"),
            (JUNIOR, "Junior"),
            (SENIOR, "Senior"),
            (GRADUATE, "Graduate"),
        ]
        year_in_school = models.CharField(
            max_length=2,
            choices=YEAR_IN_SCHOOL_CHOICES,
            default=FRESHMAN,
        )

        def is_upperclass(self):
            return self.year_in_school in {self.JUNIOR, self.SENIOR}

Though you can define a choices list outside of a model class and then refer to it, defining the choices and names for each choice inside the model class keeps all of that information with the class that uses it, and helps reference the choices (e.g, `Student.SOPHOMORE` will work anywhere that the `Student` model has been imported).

Anda dapat juga mengumpulkan pilihan tersedia anda kedalam kelompok bernama yang dapat digunakan untuk tujuan organisasi:

    MEDIA_CHOICES = [
        (
            "Audio",
            (
                ("vinyl", "Vinyl"),
                ("cd", "CD"),
            ),
        ),
        (
            "Video",
            (
                ("vhs", "VHS Tape"),
                ("dvd", "DVD"),
            ),
        ),
        ("unknown", "Unknown"),
    ]

The first element in each tuple is the name to apply to the group. The second element is an iterable of 2-tuples, with each 2-tuple containing a value and a human-readable name for an option. Grouped options may be combined with ungrouped options within a single list (such as the `'unknown'` option in this example).

Untuk setiap bidang model yang mempunyai `choices` tersetel, Djang akan menambah sebuah metode untuk mengambil nama dapat-dibaca-manusia untuk nilai saat ini bidang. Lihat `get_FOO_display()` dalam dokumentasi API basisdata.

Note that choices can be any sequence object -- not necessarily a list or tuple. This lets you construct choices dynamically. But if you find yourself hacking `choices` to be dynamic, you're probably better off using a proper database table with a `ForeignKey`. `choices` is meant for static data that doesn't change much, if ever.

Catatan

A new migration is created each time the order of `choices` changes.

meskipun `blank=False` disetel pada bidang bersama `default` kemudian sebuah etiket mengandung `"---------"` akan dibangun dengan kotak pilihan. Untuk menimpa perilaku ini, tambah sebuah tuple pada `choices` mengandung `None`; misalnya `(None, 'Your String For Display')`. Cara lain, anda dapat menggunakan string kosong daripada `None` dimana ini masuk akal - sseperti pada `CharField`.

#### Enumeration types

In addition, Django provides enumeration types that you can subclass to define choices in a concise way:

    from django.utils.translation import gettext_lazy as _

    class Student(models.Model):
        class YearInSchool(models.TextChoices):
            FRESHMAN = "FR", _("Freshman")
            SOPHOMORE = "SO", _("Sophomore")
            JUNIOR = "JR", _("Junior")
            SENIOR = "SR", _("Senior")
            GRADUATE = "GR", _("Graduate")

        year_in_school = models.CharField(
            max_length=2,
            choices=YearInSchool.choices,
            default=YearInSchool.FRESHMAN,
        )

        def is_upperclass(self):
            return self.year_in_school in {
                self.YearInSchool.JUNIOR,
                self.YearInSchool.SENIOR,
            }

These work similar to `enum` from Python's standard library, but with some modifications:

- Enum member values are a tuple of arguments to use when constructing the concrete data type. Django supports adding an extra string value to the end of this tuple to be used as the human-readable name, or `label`. The `label` can be a lazy translatable string. Thus, in most cases, the member value will be a `(value, label)` two-tuple. See below for an example of subclassing choices using a more complex data type. If a tuple is not provided, or the last item is not a (lazy) string, the `label` is automatically generated from the member name.

- A `.label` property is added on values, to return the human-readable name.

- A number of custom properties are added to the enumeration classes -- `.choices`, `.labels`, `.values`, and `.names` -- to make it easier to access lists of those separate parts of the enumeration. Use `.choices` as a suitable value to pass to `choices` in a field definition.

  Peringatan

  These property names cannot be used as member names as they would conflict.

- The use of `enum.unique()` is enforced to ensure that values cannot be defined multiple times. This is unlikely to be expected in choices for a field.

Note that using `YearInSchool.SENIOR`, `YearInSchool['SENIOR']`, or `YearInSchool('SR')` to access or lookup enum members work as expected, as do the `.name` and `.value` properties on the members.

If you don't need to have the human-readable names translated, you can have them inferred from the member name (replacing underscores with spaces and using title-case):

    >>> class Vehicle(models.TextChoices):
    ...     CAR = "C"
    ...     TRUCK = "T"
    ...     JET_SKI = "J"
    ...
    >>> Vehicle.JET_SKI.label
    'Jet Ski'

Since the case where the enum values need to be integers is extremely common, Django provides an `IntegerChoices` class. For example:

    class Card(models.Model):
        class Suit(models.IntegerChoices):
            DIAMOND = 1
            SPADE = 2
            HEART = 3
            CLUB = 4

        suit = models.IntegerField(choices=Suit.choices)

It is also possible to make use of the Enum Functional API with the caveat that labels are automatically generated as highlighted above:

    >>> MedalType = models.TextChoices("MedalType", "GOLD SILVER BRONZE")
    >>> MedalType.choices
    [('GOLD', 'Gold'), ('SILVER', 'Silver'), ('BRONZE', 'Bronze')]
    >>> Place = models.IntegerChoices("Place", "FIRST SECOND THIRD")
    >>> Place.choices
    [(1, 'First'), (2, 'Second'), (3, 'Third')]

If you require support for a concrete data type other than `int` or `str`, you can subclass `Choices` and the required concrete data type, e.g. `date` for use with `DateField`:

    class MoonLandings(datetime.date, models.Choices):
        APOLLO_11 = 1969, 7, 20, "Apollo 11 (Eagle)"
        APOLLO_12 = 1969, 11, 19, "Apollo 12 (Intrepid)"
        APOLLO_14 = 1971, 2, 5, "Apollo 14 (Antares)"
        APOLLO_15 = 1971, 7, 30, "Apollo 15 (Falcon)"
        APOLLO_16 = 1972, 4, 21, "Apollo 16 (Orion)"
        APOLLO_17 = 1972, 12, 11, "Apollo 17 (Challenger)"

There are some additional caveats to be aware of:

- Enumeration types do not support named groups.

- Because an enumeration with a concrete data type requires all values to match the type, overriding the blank label cannot be achieved by creating a member with a value of `None`. Instead, set the `__empty__` attribute on the class:

      class Answer(models.IntegerChoices):
          NO = 0, _("No")
          YES = 1, _("Yes")

          __empty__ = _("(Unknown)")

### `db_column`

`Field.``db_column`

Nama dari kolom basisdata untuk digunakan pada bidang ini. jika tidak diberikan, Django akan menggunakan nama bidang.

Jika nama kolom basisdata anda adalah kata disiapkan SQL, atau mengandung karakter yang tidak diizinkan dalam nama variabel Python -- terutama, tanda penghubung -- itu juga OK. Django mengutip nama kolom dan tabel dinelakang layar.

### `db_comment`

New in Django 4.2.

`Field.``db_comment`

The comment on the database column to use for this field. It is useful for documenting fields for individuals with direct database access who may not be looking at your Django code. For example:

    pub_date = models.DateTimeField(
        db_comment="Date and time when the article was published",
    )

### `db_index`

`Field.``db_index`

Jika``True``, indeks basisdata akan dibuat untuk bidang ini.

Gunakan pilihan `indexes` sebagai gantinya.

Where possible, use the `Meta.indexes` option instead. In nearly all cases, `indexes` provides more functionality than `db_index`. `db_index` may be deprecated in the future.

### `db_tablespace`

`Field.``db_tablespace`

Nama dari database tablespace untuk digunakan untuk indeks bidang ini, jika bidang ini diindeks. Awalan adalah pengaturan `DEFAULT_INDEX_TABLESPACE` proyek, jika disetel, atau `db_tablespace` dari model, jika ada. Jika backendtidak mendukung tablespace untuk pengindeksan, pilihan ini diabaikan.

### `default`

`Field.``default`

Nilai awalan untuk bidang. Ini dapat berupa nilai atau obyek callable. Jika callable itu akan dipanggil setiap waktu obyek baru dibuat.

The default can't be a mutable object (model instance, `list`, `set`, etc.), as a reference to the same instance of that object would be used as the default value in all new model instances. Instead, wrap the desired default in a callable. For example, if you want to specify a default `dict` for `JSONField`, use a function:

    def contact_default():
        return {"email": "to1@example.com"}

    contact_info = JSONField("ContactInfo", default=contact_default)

`lambda`s can't be used for field options like `default` because they can't be serialized by migrations. See that documentation for other caveats.

For fields like `ForeignKey` that map to model instances, defaults should be the value of the field they reference (`pk` unless `to_field` is set) instead of model instances.

The default value is used when new model instances are created and a value isn't provided for the field. When the field is a primary key, the default is also used when the field is set to `None`.

### `editable`

`Field.``editable`

Jika `False`, bidang tidak ditampilan dalam admin atau `ModelForm` lain apapun. Mereka juga dilewati selama model validation. Awalan adalah `True`.

### `error_messages`

`Field.``error_messages`

The `error_messages` argument lets you override the default messages that the field will raise. Pass in a dictionary with keys matching the error messages you want to override.

Kunci-kunci pesan kesalahan termasuk `null`, `blank`, `invalid`, `invalid_choice`, `unique`, dan `unique_for_date`. Kunci-kunci pesan kesalahan tambahan ditentukan untuk setiap bidang dalam bagian Field types dibawah.

Pesan-pesan kesalahan ini sering tidak menyebarkan ke formulir. Lihat Pertimbangan mengenai error_messages model.

### `help_text`

`Field.``help_text`

Teks "help" tambahan untuk ditampilkan dengan widget formulir. Itu sangat berguna untuk dokumentasi bahkan jika bidang anda tidak digunakan pada formulir.

Note that this value is not HTML-escaped in automatically-generated forms. This lets you include HTML in `help_text` if you so desire. For example:

    help_text = "Please use the following format: <em>YYYY-MM-DD</em>."

Alternatively you can use plain text and `django.utils.html.escape()` to escape any HTML special characters. Ensure that you escape any help text that may come from untrusted users to avoid a cross-site scripting attack.

### `primary_key`

`Field.``primary_key`

Jika `True`, bidang ini adalah primary key untuk model.

If you don't specify `primary_key=True` for any field in your model, Django will automatically add a field to hold the primary key, so you don't need to set `primary_key=True` on any of your fields unless you want to override the default primary-key behavior. The type of auto-created primary key fields can be specified per app in `AppConfig.default_auto_field` or globally in the `DEFAULT_AUTO_FIELD` setting. For more, see Bidang primary key otomatis.

`primary_key=True` berarti `null=False` dan `unique=True`. Hanya satu primary key diizinkan pada sebuah obyek.

The primary key field is read-only. If you change the value of the primary key on an existing object and then save it, a new object will be created alongside the old one.

The primary key field is set to `None` when `deleting` an object.

### `unik`

`Field.``unique`

Jika `True`, bidang ini harus unik diseluruh tabel.

This is enforced at the database level and by model validation. If you try to save a model with a duplicate value in a `unique` field, a `django.db.IntegrityError` will be raised by the model's `save()` method.

Pilihan ini adalah adalah sah pada semua jenis bidang kecuali `ManyToManyField` dan `OneToOneField`.

Catat bahwa ketika `unique` adalah `True`, anda tidak butuh menentukan `db_index`, karena `unique` menyiratkan pembuatan dari sebuah indeks.

### `unique_for_date`

`Field.``unique_for_date`

Setel ini ke nama dari `DateField` atau `DateTimeField` untuk membutuhkan dimana bidang ini unik untuk nilai dari bidang tanggal.

For example, if you have a field `title` that has `unique_for_date="pub_date"`, then Django wouldn't allow the entry of two records with the same `title` and `pub_date`.

Note that if you set this to point to a `DateTimeField`, only the date portion of the field will be considered. Besides, when `USE_TZ` is `True`, the check will be performed in the current time zone at the time the object gets saved.

This is enforced by `Model.validate_unique()` during model validation but not at the database level. If any `unique_for_date` constraint involves fields that are not part of a `ModelForm` (for example, if one of the fields is listed in `exclude` or has `editable=False`), `Model.validate_unique()` will skip validation for that particular constraint.

### `unique_for_month`

`Field.``unique_for_month`

Seperti `unique_for_date`, tetapi membutuhkan bidang unik dengan mematuhi pada bulan.

### `unique_for_year`

`Field.``unique_for_year`

Seperti `unique_for_date` dan `unique_for_month`.

### `verbose_name`

`Field.``verbose_name`

A human-readable name for the field. If the verbose name isn't given, Django will automatically create it using the field's attribute name, converting underscores to spaces. See Verbose field names.

### `validators`

`Field.``validators`

Sebuah list dari pengesah untuk berjalan untuk bidang ini. Lihat validators documentation untuk informasi lebih.

## Jenis bidang

### `AutoField`

class `AutoField`(**options)

An `IntegerField` that automatically increments according to available IDs. You usually won't need to use this directly; a primary key field will automatically be added to your model if you don't specify otherwise. See Bidang primary key otomatis.

### `BigAutoField`

class `BigAutoField`(**options)

Integer 64-bit, seperti `AutoField` kecuali itu dijamin untuk cocok nomor dari `1` sampai `9223372036854775807`.

### `BigIntegerField`

class `BigIntegerField`(**options)

A 64-bit integer, much like an `IntegerField` except that it is guaranteed to fit numbers from `-9223372036854775808` to `9223372036854775807`. The default form widget for this field is a `NumberInput`.

### `BinaryField`

class `BinaryField`(max_length=None, **options)

Sebuah bidang untuk menyimpan data binder mentah. Itu dapat diberikan `bytes`, `bytearray`, atau `memoryview`.

Secara awalan, `BinaryField` menyetel `editable` menjadi `False`, dalam kasus itu tidak dapat disertakan dalam `ModelForm`.

`BinaryField.``max_length`

  Optional. The maximum length (in bytes) of the field. The maximum length is enforced in Django's validation using `MaxLengthValidator`.

Menyalahgunakan `BinaryField`

Meskipun anda mungkin berpikir tentang menyimpan berkas-berkas dalam basisdata, pertimbangkan bahwa itu adalah rancangan buruh dalam 99% dari kasus. Bidang ini bukan sebuah penggantian untuk penangangan static files yang sesuai.

### `BooleanField`

class `BooleanField`(**options)

Sebuah bidang true/false.

Widget formulir awalan untuk bidang ini adalah `CheckboxInput`, atau `NullBooleanSelect` jika `null=True`.

Nilai awal dari `BooleanField` adalah `None` ketika `Field.default` belum ditentukan.

### `CharField`

class `CharField`(max_length=None, **options)

Bidang string, untuk string ukuran-kecil- sampai-besar.

Untuk teks besar, gunakan `TextField`.

Widget formulir awalan untuk bidang ini adalah `TextInput`.

`CharField` has the following extra arguments:

`CharField.``max_length`

  The maximum length (in characters) of the field. The `max_length` is enforced at the database level and in Django's validation using `MaxLengthValidator`. It's required for all database backends included with Django except PostgreSQL, which supports unlimited `VARCHAR` columns.

  Catatan

  Jika anda sedang menulis sebuah aplikasi yang harus dihubungkan ke banyak backend basisdata, anda harus waspada bahwa ada pembatasan pada `max_length` untuk beberapa backend. Mengacu pada database backend notes untuk rincian.

  Changed in Django 4.2:

  Support for unlimited `VARCHAR` columns was added on PostgreSQL.

`CharField.``db_collation`

  Optional. The database collation name of the field.

  Catatan

  Collation names are not standardized. As such, this will not be portable across multiple database backends.

  Oracle

  Oracle supports collations only when the `MAX_STRING_SIZE` database initialization parameter is set to `EXTENDED`.

### `DateField`

class `DateField`(auto_now=False, auto_now_add=False, **options)

Tanggal, diwakilkan dalam Python oleh instance `datetime.date`. mempunyai beberapa tambahan, argumen pilihan:

`DateField.``auto_now`

  Automatically set the field to now every time the object is saved. Useful for "last-modified" timestamps. Note that the current date is always used; it's not just a default value that you can override.

  The field is only automatically updated when calling `Model.save()`. The field isn't updated when making updates to other fields in other ways such as `QuerySet.update()`, though you can specify a custom value for the field in an update like that.

`DateField.``auto_now_add`

  Automatically set the field to now when the object is first created. Useful for creation of timestamps. Note that the current date is always used; it's not just a default value that you can override. So even if you set a value for this field when creating the object, it will be ignored. If you want to be able to modify this field, set the following instead of `auto_now_add=True`:

  - Untuk `DateField`: `default=date.today` - dari `datetime.date.today()`
  - Untuk `DateTimeField`: `default=timezone.now` - dari `django.utils.timezone.now()`

The default form widget for this field is a `DateInput`. The admin adds a JavaScript calendar, and a shortcut for "Today". Includes an additional `invalid_date` error message key.

Pilihan `auto_now_add`, `auto_now`, dan `default` saling ekslusif. Perpaduan apapun dari pilihan ini akan menghasilkan sebuah kesalahan.

Catatan

Seperti saat ini diterapkan, mengatur `auto_now` atau `auto_now_add` menjadi `True` akan menyebabkan bidang memiliki setelan `editable=False` dan `blank=True`.

Catatan

The `auto_now` and `auto_now_add` options will always use the date in the default timezone at the moment of creation or update. If you need something different, you may want to consider using your own callable default or overriding `save()` instead of using `auto_now` or `auto_now_add`; or using a `DateTimeField` instead of a `DateField` and deciding how to handle the conversion from datetime to date at display time.

### `DateTimeField`

class `DateTimeField`(auto_now=False, auto_now_add=False, **options)

Sebuah tanggal dan waktu, diwakili dalam Python oleh sebuah contoh `datetime.datetime`. Mengambil tambahan argumen sama sebagai `DateField`.

The default form widget for this field is a single `DateTimeInput`. The admin uses two separate `TextInput` widgets with JavaScript shortcuts.

### `DecimalField`

class `DecimalField`(max_digits=None, decimal_places=None, **options)

A fixed-precision decimal number, represented in Python by a `Decimal` instance. It validates the input using `DecimalValidator`.

Has the following required arguments:

`DecimalField.``max_digits`

  Angka maksimal dari bilangan diizinkan dalam angka. Catat bahwa angka ini harus lebih besar dari atau setara pada `decimal_places`.

`DecimalField.``decimal_places`

  Sejumlah tempat desiman untuk menyimpan dengan nomor.

For example, to store numbers up to `999.99` with a resolution of 2 decimal places, you'd use:

    models.DecimalField(..., max_digits=5, decimal_places=2)

Dan untuk menyimpan angka sampai pada sekitar satu milyar dengan sebuah keputusan dari 10 tempat desimal:

    models.DecimalField(..., max_digits=19, decimal_places=10)

Widget formulir awalan untuk bidang ini adalah sebuah `NumberInput` ketika `localize` adalah `False` atau `TextInput` sebaliknya.

Catatan

For more information about the differences between the `FloatField` and `DecimalField` classes, please see FloatField vs. DecimalField. You should also be aware of SQLite limitations of decimal fields.

### `DurationField`

class `DurationField`(**options)

A field for storing periods of time - modeled in Python by `timedelta`. When used on PostgreSQL, the data type used is an `interval` and on Oracle the data type is `INTERVAL DAY(9) TO SECOND(6)`. Otherwise a `bigint` of microseconds is used.

Catatan

Arithmetic with `DurationField` works in most cases. However on all databases other than PostgreSQL, comparing the value of a `DurationField` to arithmetic on `DateTimeField` instances will not work as expected.

### `EmailField`

class `EmailField`(max_length=254, **options)

A `CharField` that checks that the value is a valid email address using `EmailValidator`.

### `FileField`

class `FileField`(upload_to='', storage=None, max_length=100, **options)

Sebuah bidang berkas-unggah

Catatan

Argumen `primary_key` tidak didukung dan akan memunculkan sebuah kesalahan jika digunakan.

Has the following optional arguments:

`FileField.``upload_to`

  This attribute provides a way of setting the upload directory and file name, and can be set in two ways. In both cases, the value is passed to the `Storage.save()` method.

  If you specify a string value or a `Path`, it may contain `strftime()` formatting, which will be replaced by the date/time of the file upload (so that uploaded files don't fill up the given directory). For example:

      class MyModel(models.Model):
          # file will be uploaded to MEDIA_ROOT/uploads
          upload = models.FileField(upload_to="uploads/")
          # or...
          # file will be saved to MEDIA_ROOT/uploads/2015/01/30
          upload = models.FileField(upload_to="uploads/%Y/%m/%d/")

  If you are using the default `FileSystemStorage`, the string value will be appended to your `MEDIA_ROOT` path to form the location on the local filesystem where uploaded files will be stored. If you are using a different storage, check that storage's documentation to see how it handles `upload_to`.

  `upload_to` mungkin juga dapat dipanggil, seperti sebuah fungsi. Ini akan dipanggil untuk mendapatkan jalur unggahan, termasuk nama berkas. Panggilan iniharus menerima dua argumen dan mengembalikan jalur gaya-Unix (dengan garis miring didepan) untuk dilewatkan bersama ke sistem penyimpanan. Dua argumen adalah:

  Argument | Deskripsi
  --- | ---
  `instance` | An instance of the model where the `FileField` is defined. More specifically, this is the particular instance where the current file is being attached. Di kebanyakan kasus, obyek ini tidak akan disimpan ke basisdata dulu, jadi jika itu menggunakan `AutoField` awal, itu mungkin belum memiliki nilai untuk bidang primary key nya.
  `filename` | The filename that was originally given to the file. This may or may not be taken into account when determining the final destination path.

  Sebagai contoh:

      def user_directory_path(instance, filename):
          # file will be uploaded to MEDIA_ROOT/user_<id>/<filename>
          return "user_{0}/{1}".format(instance.user.id, filename)

      class MyModel(models.Model):
          upload = models.FileField(upload_to=user_directory_path)

`FileField.``storage`

  A storage object, or a callable which returns a storage object. This handles the storage and retrieval of your files. See Mengelola berkas for details on how to provide this object.

Widget formulir awalan untuk bidang ini adalah `ClearableFileInput`.

Menggunakan sebuah `FileField` atau sebuah `ImageField` (lihat dibawah) dalam sebuah model mengambil beberapa langkah:

1. Dalam berkas pengaturan anda, anda butuh menentukan `MEDIA_ROOT` sebagai jalur penuh ke direktori dimana anda ingin Django menyimpan berkas terunggah. (Untuk penampilan, berkas initidak disimpan di basisdata.) Tentukan `MEDIA_URL` sebagai URL dasar dari direktori. Pastikan bahwa direktori ini dapat ditulis oleh akun pengguna peladen jaringan.
2. Tambah `FileField` or `ImageField` ke model anda, menentukan pilihan `upload_to` untuk menentukan subdirectori dari `MEDIA_ROOT` untuk digunakan pada berkas-berkas terunggah.
3. All that will be stored in your database is a path to the file (relative to `MEDIA_ROOT`). You'll most likely want to use the convenience `url` attribute provided by Django. For example, if your `ImageField` is called `mug_shot`, you can get the absolute path to your image in a template with `{{ object.mug_shot.url }}`.

For example, say your `MEDIA_ROOT` is set to `'/home/media'`, and `upload_to` is set to `'photos/%Y/%m/%d'`. The `'%Y/%m/%d'` part of `upload_to` is `strftime()` formatting; `'%Y'` is the four-digit year, `'%m'` is the two-digit month and `'%d'` is the two-digit day. If you upload a file on Jan. 15, 2007, it will be saved in the directory `/home/media/photos/2007/01/15`.

If you wanted to retrieve the uploaded file's on-disk filename, or the file's size, you could use the `name` and `size` attributes respectively; for more information on the available attributes and methods, see the `File` class reference and the Mengelola berkas topic guide.

Catatan

Berkas disimpan sebagai bagian dari menyimpan model dalam basisdata, jadi berkas nama sebenarnya digunakan pada cakram tidak dapat bergantung setelah model disimpan.

The uploaded file's relative URL can be obtained using the `url` attribute. Internally, this calls the `url()` method of the underlying `Storage` class.

Note that whenever you deal with uploaded files, you should pay close attention to where you're uploading them and what type of files they are, to avoid security holes. Validate all uploaded files so that you're sure the files are what you think they are. For example, if you blindly let somebody upload files, without validation, to a directory that's within your web server's document root, then somebody could upload a CGI or PHP script and execute that script by visiting its URL on your site. Don't allow that.

Also note that even an uploaded HTML file, since it can be executed by the browser (though not by the server), can pose security threats that are equivalent to XSS or CSRF attacks.

`FileField` instances are created in your database as `varchar` columns with a default max length of 100 characters. As with other fields, you can change the maximum length using the `max_length` argument.

#### `FileField` dan `FieldFile`

class `FieldFile`

Ketika anda mengakses `FileField` pada model, anda diberikan sebah contoh dari `FieldFile` sebagai sebuah proxy untuk mengakses berkas pokok.

The API of `FieldFile` mirrors that of `File`, with one key difference: The object wrapped by the class is not necessarily a wrapper around Python's built-in file object. Instead, it is a wrapper around the result of the `Storage.open()` method, which may be a `File` object, or it may be a custom storage's implementation of the `File` API.

In addition to the API inherited from `File` such as `read()` and `write()`, `FieldFile` includes several methods that can be used to interact with the underlying file:

Peringatan

Dua metode dari kelas ini, `save()` dan `delete()`, awalan pada menyimpan obyek model dari `FieldFile` terkait dalam basisdata.

`FieldFile.``name`

Nama dari berkas termasuk jalur relatif dari akar dari `Storage` dari `FileField` terkait.

`FieldFile.``path`

A read-only property to access the file's local filesystem path by calling the `path()` method of the underlying `Storage` class.

`FieldFile.``size`

Hasil dari metode pokok `Storage.size()`.

`FieldFile.``url`

A read-only property to access the file's relative URL by calling the `url()` method of the underlying `Storage` class.

`FieldFile.``open`(mode='rb')

Opens or reopens the file associated with this instance in the specified `mode`. Unlike the standard Python `open()` method, it doesn't return a file descriptor.

Since the underlying file is opened implicitly when accessing it, it may be unnecessary to call this method except to reset the pointer to the underlying file or to change the `mode`.

`FieldFile.``close`()

Berperilaku seperti metode `file.close()` Python standar dan menutup berkas berkaitan dengan contoh ini.

`FieldFile.``save`(name, content, save=True)

This method takes a filename and file contents and passes them to the storage class for the field, then associates the stored file with the model field. If you want to manually associate file data with `FileField` instances on your model, the `save()` method is used to persist that file data.

Takes two required arguments: `name` which is the name of the file, and `content` which is an object containing the file's contents. The optional `save` argument controls whether or not the model instance is saved after the file associated with this field has been altered. Defaults to `True`.

Note that the `content` argument should be an instance of `django.core.files.File`, not Python's built-in file object. You can construct a `File` from an existing Python file object like this:

    from django.core.files import File

    # Open an existing file using Python's built-in open()
    f = open("/path/to/hello.world")
    myfile = File(f)

Atau anda dapat membangun satu dari sebush string Python seperti ini:

    from django.core.files.base import ContentFile

    myfile = ContentFile("hello world")

Untuk informasi lebih, lihat Mengelola berkas.

`FieldFile.``delete`(save=True)

Deletes the file associated with this instance and clears all attributes on the field. Note: This method will close the file if it happens to be open when `delete()` is called.

The optional `save` argument controls whether or not the model instance is saved after the file associated with this field has been deleted. Defaults to `True`.

Note that when a model is deleted, related files are not deleted. If you need to cleanup orphaned files, you'll need to handle it yourself (for instance, with a custom management command that can be run manually or scheduled to run periodically via e.g. cron).

### `FilePathField`

class `FilePathField`(path='', match=None, recursive=False, allow_files=True, allow_folders=False, max_length=100, **options)

A `CharField` whose choices are limited to the filenames in a certain directory on the filesystem. Has some special arguments, of which the first is required:

`FilePathField.``path`

  Required. The absolute filesystem path to a directory from which this `FilePathField` should get its choices. Example: `"/home/images"`.

  `path` may also be a callable, such as a function to dynamically set the path at runtime. Example:

      import os
      from django.conf import settings
      from django.db import models

      def images_path():
          return os.path.join(settings.LOCAL_FILE_DIR, "images")

      class MyModel(models.Model):
          file = models.FilePathField(path=images_path)

`FilePathField.``match`

  Optional. A regular expression, as a string, that `FilePathField` will use to filter filenames. Note that the regex will be applied to the base filename, not the full path. Example: `"foo.*\.txt$"`, which will match a file called `foo23.txt` but not `bar.txt` or `foo23.png`.

`FilePathField.``recursive`

  Optional. Either `True` or `False`. Default is `False`. Specifies whether all subdirectories of `path` should be included

`FilePathField.``allow_files`

  Optional. Either `True` or `False`. Default is `True`. Specifies whether files in the specified location should be included. Either this or `allow_folders` must be `True`.

`FilePathField.``allow_folders`

  Optional. Either `True` or `False`. Default is `False`. Specifies whether folders in the specified location should be included. Either this or `allow_files` must be `True`.

The one potential gotcha is that `match` applies to the base filename, not the full path. So, this example:

    FilePathField(path="/home/images", match="foo.*", recursive=True)

...will match `/home/images/foo.png` but not `/home/images/foo/bar.png` because the `match` applies to the base filename (`foo.png` and `bar.png`).

`FilePathField` instances are created in your database as `varchar` columns with a default max length of 100 characters. As with other fields, you can change the maximum length using the `max_length` argument.

### `FloatField`

class `FloatField`(**options)

Angka floating-point diwakilkan oleh Python oleh instance `float`.

Widget formulir awalan untuk bidang ini adalah sebuah `NumberInput` ketika `localize` adalah `False` atau `TextInput` sebaliknya.

`FloatField` vs. `DecimalField`

The `FloatField` class is sometimes mixed up with the `DecimalField` class. Although they both represent real numbers, they represent those numbers differently. `FloatField` uses Python's `float` type internally, while `DecimalField` uses Python's `Decimal` type. For information on the difference between the two, see Python's documentation for the `decimal` module.

### `GenericIPAddressField`

class `GenericIPAddressField`(protocol='both', unpack_ipv4=False, **options)

An IPv4 or IPv6 address, in string format (e.g. `192.0.2.30` or `2a02:42fe::4`). The default form widget for this field is a `TextInput`.

Normalisasi alamat IPv6 mengikuti RFC 4291#section-2.2 bagian 2.2, termasuk menggunakan bentuk IPv4 disarankan dalam paragraf 3 dari bagian itu, seperti `::ffff:192.0.2.0`. Sebagai contoh, `2001:0::0:01` akan dinormalkan menjadi `2001::1`, dan `::ffff:0a0a:0a0a` menjadi `::ffff:10.10.10.10`. Semau karakter dirubah menjadi huruf kecil.

`GenericIPAddressField.``protocol`

  Limits valid inputs to the specified protocol. Accepted values are `'both'` (default), `'IPv4'` or `'IPv6'`. Matching is case insensitive.

`GenericIPAddressField.``unpack_ipv4`

  Unpacks IPv4 mapped addresses like `::ffff:192.0.2.1`. If this option is enabled that address would be unpacked to `192.0.2.1`. Default is disabled. Can only be used when `protocol` is set to `'both'`.

Jika anda mengizinkan nilai kosong, anda harus mengizinkan nilai null karena nilai kosong disimpan sebagai null.

### `ImageField`

class `ImageField`(upload_to=None, height_field=None, width_field=None, max_length=100, **options)

Inherits all attributes and methods from `FileField`, but also validates that the uploaded object is a valid image.

In addition to the special attributes that are available for `FileField`, an `ImageField` also has `height` and `width` attributes.

To facilitate querying on those attributes, `ImageField` has the following optional arguments:

`ImageField.``height_field`

  Name of a model field which will be auto-populated with the height of the image each time the model instance is saved.

`ImageField.``width_field`

  Name of a model field which will be auto-populated with the width of the image each time the model instance is saved.

Membutuhkan pustaka Pillow

`ImageField` instances are created in your database as `varchar` columns with a default max length of 100 characters. As with other fields, you can change the maximum length using the `max_length` argument.

Widget formulir awalan untuk bidang ini adalah `ClearableFileInput`.

### `IntegerField`

class `IntegerField`(**options)

Sebuah integer. Nilai dari `-2147483648` sampai `2147483647` aman dalam semua basisdata didukung oleh Django.

Itu menggunakan `MinValueValidator` dan `MaxValueValidator` untuk mensahkan masukan berdasarkan pada nilai yang didukung basisdata awalan.

Widget formulir awalan untuk bidang ini adalah sebuah `NumberInput` ketika `localize` adalah `False` atau `TextInput` sebaliknya.

### `JSONField`

class `JSONField`(encoder=None, decoder=None, **options)

Sebuah bidang untuk menyimpan data tersandi JSON. Dalam Python data diwakili dalam bentuk asli Python nya: dictionary, string, angka, booelan dan `None`.

`JSONField` is supported on MariaDB, MySQL, Oracle, PostgreSQL, and SQLite (with the JSON1 extension enabled).

`JSONField.``encoder`

  An optional `json.JSONEncoder` subclass to serialize data types not supported by the standard JSON serializer (e.g. `datetime.datetime` or `UUID`). For example, you can use the `DjangoJSONEncoder` class.

  Awalan untuk `json.JSONEncoder`.

`JSONField.``decoder`

  An optional `json.JSONDecoder` subclass to deserialize the value retrieved from the database. The value will be in the format chosen by the custom encoder (most often a string). Your deserialization may need to account for the fact that you can't be certain of the input type. For example, you run the risk of returning a `datetime` that was actually a string that just happened to be in the same format chosen for `datetime`s.

  Awalan untuk `json.JSONDecoder`.

To query `JSONField` in the database, see Meminta JSONField.

Default value

If you give the field a `default`, ensure it's a callable such as the `dict` class or a function that returns a fresh object each time. Incorrectly using a mutable object like `default={}` or `default=[]` creates a mutable default that is shared between all instances.

Indexing

`Index` and `Field.db_index` both create a B-tree index, which isn't particularly helpful when querying `JSONField`. On PostgreSQL only, you can use `GinIndex` that is better suited.

Pengguna PostgreSQL

PostgreSQL mempunyai dua jenis data berdasarkan JSON asli: `json` dan `jsonb`. Perbedaan utama diantara mereka adalah bagaimana mereka disimpan dan bagaimana mereka dapat diminta. Bidang `json` PostgreSQL disimpan sebagai perwakilan string asli dari JSON dan harus disandikan dengan cepat ketika permintaan berdasarkan pada kunci-kunci. Bidang `jsonb` disimpan berdasarkan pada struktur sebenarnya dari JSON yang mengizinkan pengindeksan. Pertukaran adalah tambahan biaya kecil pada menulis ke bidang `jsonb` field. `JSONField` menggunakan `jsonb`.

Pengguna Oracle

Oracle Database does not support storing JSON scalar values. Only JSON objects and arrays (represented in Python using `dict` and `list`) are supported.

### `PositiveBigIntegerField`

class `PositiveBigIntegerField`(**options)

Like a `PositiveIntegerField`, but only allows values under a certain (database-dependent) point. Values from `0` to `9223372036854775807` are safe in all databases supported by Django.

### `PositiveIntegerField`

class `PositiveIntegerField`(**options)

Like an `IntegerField`, but must be either positive or zero (`0`). Values from `0` to `2147483647` are safe in all databases supported by Django. The value `0` is accepted for backward compatibility reasons.

### `PositiveSmallIntegerField`

class `PositiveSmallIntegerField`(**options)

Like a `PositiveIntegerField`, but only allows values under a certain (database-dependent) point. Values from `0` to `32767` are safe in all databases supported by Django.

### `SlugField`

class `SlugField`(max_length=50, **options)

Slug is a newspaper term. A slug is a short label for something, containing only letters, numbers, underscores or hyphens. They're generally used in URLs.

Like a CharField, you can specify `max_length` (read the note about database portability and `max_length` in that section, too). If `max_length` is not specified, Django will use a default length of 50.

menunjuk pengaturan `Field.db_index` ke `True`.

Itu sering berguna untuk otomatis mengisi dimuka sebuah SlugField berdasarkan pada nilai dari beberapa nilai lain. Anda dapat melakukan ini otomatis di admin menggunakan `prepopulated_fields`.

Itu menggunakan `validate_slug` atau `validate_unicode_slug` for validation.

`SlugField.``allow_unicode`

  Jika `True`, bidang menerima huruf Unicode ebagai tambahan pada huruf ASCII. Awalan menjadi `False`.

### `SmallAutoField`

class `SmallAutoField`(**options)

Like an `AutoField`, but only allows values under a certain (database-dependent) limit. Values from `1` to `32767` are safe in all databases supported by Django.

### `SmallIntegerField`

class `SmallIntegerField`(**options)

Like an `IntegerField`, but only allows values under a certain (database-dependent) point. Values from `-32768` to `32767` are safe in all databases supported by Django.

### `TextField`

class `TextField`(**options)

A large text field. The default form widget for this field is a `Textarea`.

Jika anda menentukan atribut `max_length`, itu akan dipantulkan di widget `Textarea` dari bidang formulir dibangkitkan-otomatis. Bagaimanapun itu tidak dipaksa pada model atau tingkatan basisdata. Gunakan `CharField` untuk itu.

`TextField.``db_collation`

  Optional. The database collation name of the field.

  Catatan

  Collation names are not standardized. As such, this will not be portable across multiple database backends.

  Oracle

  Oracle does not support collations for a `TextField`.

### `TimeField`

class `TimeField`(auto_now=False, auto_now_add=False, **options)

A time, represented in Python by a `datetime.time` instance. Accepts the same auto-population options as `DateField`.

The default form widget for this field is a `TimeInput`. The admin adds some JavaScript shortcuts.

### `URLField`

class `URLField`(max_length=200, **options)

Sebuah `CharField` untuk URL, disahkan oleh `URLValidator`.

The default form widget for this field is a `URLInput`.

Seperti semua `CharField` subclasses, `URLField` mengambil pilihan argumen `max_length`. Jika anda tidak menentukan `max_length`, sebuah awalan 200 digunakan.

### `UUIDField`

class `UUIDField`(**options)

A field for storing universally unique identifiers. Uses Python's `UUID` class. When used on PostgreSQL, this stores in a `uuid` datatype, otherwise in a `char(32)`.

Universally unique identifiers are a good alternative to `AutoField` for `primary_key`. The database will not generate the UUID for you, so it is recommended to use `default`:

    import uuid
    from django.db import models

    class MyUUIDModel(models.Model):
        id = models.UUIDField(primary_key=True, default=uuid.uuid4, editable=False)
        # other fields

Catata bahwa sebuah callable (dengan tanda kurung dihapus) dilewatkan pada `default`, bukan sebuah instance dari `UUID`.

Lookups on PostgreSQL

Using `iexact`, `contains`, `icontains`, `startswith`, `istartswith`, `endswith`, or `iendswith` lookups on PostgreSQL don't work for values without hyphens, because PostgreSQL stores them in a hyphenated uuid datatype type.

## Bidang hubungan

Django juga menentukan kumpulan bidang yang mewakili hubungan.

### `ForeignKey`

class `ForeignKey`(to, on_delete, **options)

Sebuah hubungan many-to-one. Membutuhkan dua argumen penempatan: kelas dimana model dihubungkan dan pilihan `on_delete`.

Untuk membuat sebuah hubungan rekursif -- sebuah obyek yang mempunyai hubungan many-to-many dengan itu sendiri -- gunakan `models.ForeignKey('self', on_delete=models.CASCADE)`.

Jika anda butuh membuat sebuah hubungan pada sebuah model yang belum ditentukan, anda dapat menggunakan nama dari model, daripada obyek model itu sendiri:

    from django.db import models

    class Car(models.Model):
        manufacturer = models.ForeignKey(
            "Manufacturer",
            on_delete=models.CASCADE,
        )
        # ...

    class Manufacturer(models.Model):
        # ...
        pass

Relationships defined this way on abstract models are resolved when the model is subclassed as a concrete model and are not relative to the abstract model's `app_label`:

`products/models.py`

    from django.db import models

    class AbstractCar(models.Model):
        manufacturer = models.ForeignKey("Manufacturer", on_delete=models.CASCADE)

        class Meta:
            abstract = True

`production/models.py`

    from django.db import models
    from products.models import AbstractCar

    class Manufacturer(models.Model):
        pass

    class Car(AbstractCar):
        pass

    # Car.manufacturer will point to `production.Manufacturer` here.

Untuk mengacu pada model-model ditentukan dalam aplikasi lain, anda dapat secara jelas menentukan sebuah model dengan label aplikasi penuh. Sebagai contoh, jika model `Manufacturer` diatas ditentukan dalam aplikasi lain disebut `production`, anda akan butuh menggunakan:

    class Car(models.Model):
        manufacturer = models.ForeignKey(
            "production.Manufacturer",
            on_delete=models.CASCADE,
        )

This sort of reference, called a lazy relationship, can be useful when resolving circular import dependencies between two applications.

Sebuah indeks basisdata otomatis dibuat pada `ForeignKey`. Anda dapat meniadakan ini dengan mengatur `db_index` menjadi `False`. Anda ingin menghindari kelebihan dari sebuah indeks jika anda membuat sebuah foreign key untuk ketetapan daripada penggabungan, atau jika anda akan membuat indeks cara lain seperti sebagian atau banyak indeks kolom.

#### Perwakilan Basisdata

Dibelakang layar, Django menambahkan `"_id"` ke nama bidang untuk membuat nama kolom basisdatanya. Dalam contoh diatas, tabel basisdata untuk model `Car` akan mempunyai kolom `manufacturer_id`. (Anda dapat merubah ini secara jelas dengan menentukan `db_column`) Bagaimanapun, kode anda jangan pernah berurusan dengan nama kolom basisdata, meskipun anda menulis SQL penyesuaian. Anda akan selalu berurusan dengan nama bidang dari obyek model anda.

#### Penjelasan

`ForeignKey` menerima argumen lain yang menentukan rincian dari bagaimana hubungan bekerja.

`ForeignKey.``on_delete`

  When an object referenced by a `ForeignKey` is deleted, Django will emulate the behavior of the SQL constraint specified by the `on_delete` argument. For example, if you have a nullable `ForeignKey` and you want it to be set null when the referenced object is deleted:

      user = models.ForeignKey(
          User,
          models.SET_NULL,
          blank=True,
          null=True,
      )

  `on_delete` doesn't create an SQL constraint in the database. Support for database-level cascade options may be implemented later.

Nilai-nilai kemungkinan untuk `on_delete` ditemukan dalam `django.db.models`:

- `CASCADE`

    Cascade deletes. Django emulates the behavior of the SQL constraint ON DELETE CASCADE and also deletes the object containing the ForeignKey.

    `Model.delete()` isn't called on related models, but the `pre_delete` and `post_delete` signals are sent for all deleted objects.

- `PROTECT`

    Prevent deletion of the referenced object by raising `ProtectedError`, a subclass of `django.db.IntegrityError`.

- `RESTRICT`

    Prevent deletion of the referenced object by raising `RestrictedError` (a subclass of `django.db.IntegrityError`). Unlike `PROTECT`, deletion of the referenced object is allowed if it also references a different object that is being deleted in the same operation, but via a `CASCADE` relationship.

    Pertimbangkan kumpulan model ini:

        class Artist(models.Model):
            name = models.CharField(max_length=10)

        class Album(models.Model):
            artist = models.ForeignKey(Artist, on_delete=models.CASCADE)

        class Song(models.Model):
            artist = models.ForeignKey(Artist, on_delete=models.CASCADE)
            album = models.ForeignKey(Album, on_delete=models.RESTRICT)

    `Artist` can be deleted even if that implies deleting an `Album` which is referenced by a `Song`, because `Song` also references `Artist` itself through a cascading relationship. For example:

        >>> artist_one = Artist.objects.create(name="artist one")
        >>> artist_two = Artist.objects.create(name="artist two")
        >>> album_one = Album.objects.create(artist=artist_one)
        >>> album_two = Album.objects.create(artist=artist_two)
        >>> song_one = Song.objects.create(artist=artist_one, album=album_one)
        >>> song_two = Song.objects.create(artist=artist_one, album=album_two)
        >>> album_one.delete()
        # Raises RestrictedError.
        >>> artist_two.delete()
        # Raises RestrictedError.
        >>> artist_one.delete()
        (4, {'Song': 2, 'Album': 1, 'Artist': 1})

- `SET_NULL`

    Setel `ForeignKey` null; ini hanya memungkinkan jika `null` adalah `True`.

- `SET_DEFAULT`

    Setel `ForeignKey` ke nilai awalannya; sebuah awalan untuk `ForeignKey` harus disetel.

- `SET`()

    Set the `ForeignKey` to the value passed to `SET()`, or if a callable is passed in, the result of calling it. In most cases, passing a callable will be necessary to avoid executing queries at the time your `models.py` is imported:

        from django.conf import settings
        from django.contrib.auth import get_user_model
        from django.db import models

        def get_sentinel_user():
            return get_user_model().objects.get_or_create(username="deleted")[0]

        class MyModel(models.Model):
            user = models.ForeignKey(
                settings.AUTH_USER_MODEL,
                on_delete=models.SET(get_sentinel_user),
            )

- `DO_NOTHING`

    Take no action. If your database backend enforces referential integrity, this will cause an `IntegrityError` unless you manually add an SQL `ON DELETE` constraint to the database field.

`ForeignKey.``limit_choices_to`

  Sets a limit to the available choices for this field when this field is rendered using a `ModelForm` or the admin (by default, all objects in the queryset are available to choose). Either a dictionary, a `Q` object, or a callable returning a dictionary or `Q` object can be used.

  Sebagai contoh:

      staff_member = models.ForeignKey(
          User,
          on_delete=models.CASCADE,
          limit_choices_to={"is_staff": True},
      )

  causes the corresponding field on the `ModelForm` to list only `Users` that have `is_staff=True`. This may be helpful in the Django admin.

  The callable form can be helpful, for instance, when used in conjunction with the Python `datetime` module to limit selections by date range. For example:

      def limit_pub_date_choices():
          return {"pub_date__lte": datetime.date.today()}

      limit_choices_to = limit_pub_date_choices

  If `limit_choices_to` is or returns a `Q object`, which is useful for complex queries, then it will only have an effect on the choices available in the admin when the field is not listed in `raw_id_fields` in the `ModelAdmin` for the model.

  Catatan

  If a callable is used for `limit_choices_to`, it will be invoked every time a new form is instantiated. It may also be invoked when a model is validated, for example by management commands or the admin. The admin constructs querysets to validate its form inputs in various edge cases multiple times, so there is a possibility your callable may be invoked several times.

`ForeignKey.``related_name`

  The name to use for the relation from the related object back to this one. It's also the default value for `related_query_name` (the name to use for the reverse filter name from the target model). See the related objects documentation for a full explanation and example. Note that you must set this value when defining relations on abstract models; and when you do so some special syntax is available.

  If you'd prefer Django not to create a backwards relation, set `related_name` to `'+'` or end it with `'+'`. For example, this will ensure that the `User` model won't have a backwards relation to this model:

      user = models.ForeignKey(
          User,
          on_delete=models.CASCADE,
          related_name="+",
      )

`ForeignKey.``related_query_name`

  The name to use for the reverse filter name from the target model. It defaults to the value of `related_name` or `default_related_name` if set, otherwise it defaults to the name of the model:

      # Declare the ForeignKey with related_query_name
      class Tag(models.Model):
          article = models.ForeignKey(
              Article,
              on_delete=models.CASCADE,
              related_name="tags",
              related_query_name="tag",
          )
          name = models.CharField(max_length=255)

      # That's now the name of the reverse filter
      Article.objects.filter(tag__name="important")

  Like `related_name`, `related_query_name` supports app label and class interpolation via some special syntax.

`ForeignKey.``to_field`

  The field on the related object that the relation is to. By default, Django uses the primary key of the related object. If you reference a different field, that field must have `unique=True`.

`ForeignKey.``db_constraint`

  Controls whether or not a constraint should be created in the database for this foreign key. The default is `True`, and that's almost certainly what you want; setting this to `False` can be very bad for data integrity. That said, here are some scenarios where you might want to do this:

  - Anda mempunyai warisan data yang tidak sah.
  - Anda sedang memecah basisdata anda.

  Jika ini disetel menjadi `False`, mengakses obyek terkait yang tidak ada akan memunculkan pengecualian `DoesNotExist` nya.

`ForeignKey.``swappable`

  Controls the migration framework's reaction if this `ForeignKey` is pointing at a swappable model. If it is `True` - the default - then if the `ForeignKey` is pointing at a model which matches the current value of `settings.AUTH_USER_MODEL` (or another swappable model setting) the relationship will be stored in the migration using a reference to the setting, not to the model directly.

  You only want to override this to be `False` if you are sure your model should always point toward the swapped-in model - for example, if it is a profile model designed specifically for your custom user model.

  Setting it to `False` does not mean you can reference a swappable model even if it is swapped out - `False` means that the migrations made with this ForeignKey will always reference the exact model you specify (so it will fail hard if the user tries to run with a User model you don't support, for example).

  Jika dalam keraguan, tinggalkan itu ke awalan menjadi `True`.

### `ManyToManyField`

class `ManyToManyField`(to, **options)

A many-to-many relationship. Requires a positional argument: the class to which the model is related, which works exactly the same as it does for `ForeignKey`, including recursive and lazy relationships.

Related objects can be added, removed, or created with the field's `RelatedManager`.

#### Perwakilan Basisdata

Behind the scenes, Django creates an intermediary join table to represent the many-to-many relationship. By default, this table name is generated using the name of the many-to-many field and the name of the table for the model that contains it. Since some databases don't support table names above a certain length, these table names will be automatically truncated and a uniqueness hash will be used, e.g. `author_books_9cdf`. You can manually provide the name of the join table using the `db_table` option.

#### Penjelasan

`ManyToManyField` accepts an extra set of arguments -- all optional -- that control how the relationship functions.

`ManyToManyField.``related_name`

  Sama seperti `ForeignKey.related_name`.

`ManyToManyField.``related_query_name`

  Sama seperti `ForeignKey.related_query_name`.

`ManyToManyField.``limit_choices_to`

  Sama seperti `ForeignKey.limit_choices_to`.

`ManyToManyField.``symmetrical`

  Hanya digunakan dalam pengertian dari ManyToManyFields pada diri sendiri. pertimbangkan model berikut:

      from django.db import models

      class Person(models.Model):
          friends = models.ManyToManyField("self")

  When Django processes this model, it identifies that it has a `ManyToManyField` on itself, and as a result, it doesn't add a `person_set` attribute to the `Person` class. Instead, the `ManyToManyField` is assumed to be symmetrical -- that is, if I am your friend, then you are my friend.

  If you do not want symmetry in many-to-many relationships with `self`, set `symmetrical` to `False`. This will force Django to add the descriptor for the reverse relationship, allowing `ManyToManyField` relationships to be non-symmetrical.

`ManyToManyField.``through`

  Django will automatically generate a table to manage many-to-many relationships. However, if you want to manually specify the intermediary table, you can use the `through` option to specify the Django model that represents the intermediate table that you want to use.

  Penggunaan paling umum dari pilihan ini adalah ketika anda ingin mengkaitkan extra data with a many-to-many relationship.

  Catatan

  If you don't want multiple associations between the same instances, add a `UniqueConstraint` including the from and to fields. Django's automatically generated many-to-many tables include such a constraint.

  Catatan

  Recursive relationships using an intermediary model can't determine the reverse accessors names, as they would be the same. You need to set a `related_name` to at least one of them. If you'd prefer Django not to create a backwards relation, set `related_name` to `'+'`.

  If you don't specify an explicit `through` model, there is still an implicit `through` model class you can use to directly access the table created to hold the association. It has three fields to link the models.

  Jika sumber dan sasarn model berbeda, bidang-bidang berikut akan dibangkitkan:

  - `id`: primary key dari hubungan.
  - `<containing_model>_id`: `id` dari model yang menyatakan `ManyToManyField`.
  - `<other_model>_id`: `id` dari model yang menunjuk pada `ManyToManyField`.

  Jika `ManyToManyField` menunjuk dari dan ke model sama, bidang-bidang berikut dibangkitkan:

  - `id`: primary key dari hubungan.
  - `from_<model>_id`: the `id` of the instance which points at the model (i.e. the source instance).
  - `to_<model>_id`: `id` dari instance dimana hubungan menunjuk (yaitu sasaran instance model).

  This class can be used to query associated records for a given model instance like a normal model:

      Model.m2mfield.through.objects.all()

`ManyToManyField.``through_fields`

  Only used when a custom intermediary model is specified. Django will normally determine which fields of the intermediary model to use in order to establish a many-to-many relationship automatically. However, consider the following models:

      from django.db import models

      class Person(models.Model):
          name = models.CharField(max_length=50)

      class Group(models.Model):
          name = models.CharField(max_length=128)
          members = models.ManyToManyField(
              Person,
              through="Membership",
              through_fields=("group", "person"),
          )

      class Membership(models.Model):
          group = models.ForeignKey(Group, on_delete=models.CASCADE)
          person = models.ForeignKey(Person, on_delete=models.CASCADE)
          inviter = models.ForeignKey(
              Person,
              on_delete=models.CASCADE,
              related_name="membership_invites",
          )
          invite_reason = models.CharField(max_length=64)

  `Membership` has two foreign keys to `Person` (`person` and `inviter`), which makes the relationship ambiguous and Django can't know which one to use. In this case, you must explicitly specify which foreign keys Django should use using `through_fields`, as in the example above.

  `through_fields` accepts a 2-tuple `('field1', 'field2')`, where `field1` is the name of the foreign key to the model the `ManyToManyField` is defined on (`group` in this case), and `field2` the name of the foreign key to the target model (`person` in this case).

  When you have more than one foreign key on an intermediary model to any (or even both) of the models participating in a many-to-many relationship, you must specify `through_fields`. This also applies to recursive relationships when an intermediary model is used and there are more than two foreign keys to the model, or you want to explicitly specify which two Django should use.

`ManyToManyField.``db_table`

  The name of the table to create for storing the many-to-many data. If this is not provided, Django will assume a default name based upon the names of: the table for the model defining the relationship and the name of the field itself.

`ManyToManyField.``db_constraint`

  Controls whether or not constraints should be created in the database for the foreign keys in the intermediary table. The default is `True`, and that's almost certainly what you want; setting this to `False` can be very bad for data integrity. That said, here are some scenarios where you might want to do this:

  - Anda mempunyai warisan data yang tidak sah.
  - Anda sedang memecah basisdata anda.

  Itu adalah sebuah kesalahan untuk melewatkan kedua `db_constraint` dan `through`.

`ManyToManyField.``swappable`

  Controls the migration framework's reaction if this `ManyToManyField` is pointing at a swappable model. If it is `True` - the default - then if the `ManyToManyField` is pointing at a model which matches the current value of `settings.AUTH_USER_MODEL` (or another swappable model setting) the relationship will be stored in the migration using a reference to the setting, not to the model directly.

  You only want to override this to be `False` if you are sure your model should always point toward the swapped-in model - for example, if it is a profile model designed specifically for your custom user model.

  Jika dalam keraguan, tinggalkan itu ke awalan menjadi `True`.

`ManyToManyField` tidak mendukung `validators`.

`null` tidak mempunyai pengaruh sejak tidak ada cara untuk membutuhkan hubungan pada tingkat basisdata.

### `OneToOneField`

class `OneToOneField`(to, on_delete, parent_link=False, **options)

A one-to-one relationship. Conceptually, this is similar to a `ForeignKey` with `unique=True`, but the "reverse" side of the relation will directly return a single object.

This is most useful as the primary key of a model which "extends" another model in some way; Warisan banyak-tabel is implemented by adding an implicit one-to-one relation from the child model to the parent model, for example.

One positional argument is required: the class to which the model will be related. This works exactly the same as it does for `ForeignKey`, including all the options regarding recursive and lazy relationships.

If you do not specify the `related_name` argument for the `OneToOneField`, Django will use the lowercase name of the current model as default value.

Dengan contoh berikut:

    from django.conf import settings
    from django.db import models

    class MySpecialUser(models.Model):
        user = models.OneToOneField(
            settings.AUTH_USER_MODEL,
            on_delete=models.CASCADE,
        )
        supervisor = models.OneToOneField(
            settings.AUTH_USER_MODEL,
            on_delete=models.CASCADE,
            related_name="supervisor_of",
        )

your resulting `User` model will have the following attributes:

    >>> user = User.objects.get(pk=1)
    >>> hasattr(user, "myspecialuser")
    True
    >>> hasattr(user, "supervisor_of")
    True

A `RelatedObjectDoesNotExist` exception is raised when accessing the reverse relationship if an entry in the related table doesn't exist. This is a subclass of the target model's `Model.DoesNotExist` exception and can be accessed as an attribute of the reverse accessor. For example, if a user doesn't have a supervisor designated by `MySpecialUser`:

    try:
        user.supervisor_of
    except User.supervisor_of.RelatedObjectDoesNotExist:
        pass

Additionally, `OneToOneField` accepts all of the extra arguments accepted by `ForeignKey`, plus one extra argument:

`OneToOneField.``parent_link`

  When `True` and used in a model which inherits from another concrete model, indicates that this field should be used as the link back to the parent class, rather than the extra `OneToOneField` which would normally be implicitly created by subclassing.

Lihat One-to-one relationships untuk contoh penggunaan dari `OneToOneField`.

## Acuan API Bidang

class `Field`

  `Field` is an abstract class that represents a database table column. Django uses fields to create the database table (`db_type()`), to map Python types to database (`get_prep_value()`) and vice-versa (`from_db_value()`).

  A field is thus a fundamental piece in different Django APIs, notably, `models` and `querysets`.

  In models, a field is instantiated as a class attribute and represents a particular table column, see Model. It has attributes such as `null` and `unique`, and methods that Django uses to map the field value to database-specific values.

  Sebuah `Field` adalah subkelas dari `RegisterLookupMixin` dan dengan demikian kedua `Transform` dan `Lookup` dapat didaftarkan pada itu untuk digunakan dalam (misalnya `field_name__exact="foo"`) `QuerySet`. Semua built-in lookups didaftarkan secara awalan.

  All of Django's built-in fields, such as `CharField`, are particular implementations of `Field`. If you need a custom field, you can either subclass any of the built-in fields or write a `Field` from scratch. In either case, see Bagaimana membuat bidang model disesuaikan.

  `description`

    Gambaran bertele-tele dari bidang, misalnya aplikasi `django.contrib.admindocs`.

    Gambaran dapat berupa dari bentuk

        description = _("String (up to %(max_length)s)")

    dimana argumen-argumen ditambahkan dari `__dict__` bidang-bidang.

  `descriptor_class`

    A class implementing the descriptor protocol that is instantiated and assigned to the model instance attribute. The constructor must accept a single argument, the `Field` instance. Overriding this class attribute allows for customizing the get and set behavior.

  Untuk memetakan sebuah `Field` pada jenis khusus-basisdata, Django membuka beberapa metode-metode:

  `get_internal_type`()

    Mengembalikan sebuah string menamakan bidang ini untuk tujuan khusus backend. Secara awalan, itu mengembalikan nama kelas.

    Lihat Menyamai jenis bidang siap pakai untuk penggunaan dalam bidang penyesuaian.

  `db_type`(connection)

    Mengembalikan jenis data kolom basisdata untuk `Field`, dimasukkan kedalam akun `connection`.

    Lihat Jenis basisdata penyesuaian untuk penggunaan dalam bidang penyesuaian.

  `rel_db_type`(connection)

    Returns the database column data type for fields such as `ForeignKey` and `OneToOneField` that point to the `Field`, taking into account the `connection`.

    Lihat Jenis basisdata penyesuaian untuk penggunaan dalam bidang penyesuaian.

  Ada tiga keadaan utama dimana Django butuh berinteraksi dengan backend basisdata dan bidang-bidang:

  - ketika itu meminta basisdata (nilai Python -> nilai backend basisdata)
  - ketika itu memuat data dari basisdata (nilai backend basisdata -> nilai Python)
  - ketika itu menyimpan ke basisdata (nilai Python -> nilai backend basisdata)

  Ketika meminta, `get_db_prep_value()` dan `get_prep_value()` digunakan:

  `get_prep_value`(value)

    `value` adalah nilai saat ini dari atribut model, dan metode harus mengembalikan data dalam bentuk yang telah dipersiapkan untuk digunakan sebagai sebuah parameter dalam sebuah permintaan.

    Lihat Mengubah obyek Python ke nilai pencarian untuk penggunaan.

  `get_db_prep_value`(value, connection, prepared=False)

    Merubah `value` pada nilai khusus-backend. Secara awalan itu mengembalikan `value` jika `prepared=True` dan `get_prep_value()` jika adalah `False`.

    Lihat Mengubah nilai pencarian ke nilai basisdata untuk penggunaan.

  Ketika memuat data, `from_db_value()` digunakan:

  `from_db_value`(value, expression, connection)

    Merubah nilai ketika dikembalikan oleh basisdata ke obyek Python. Itu adalah balikan dari `get_prep_value()`.

    Metode ini tidak digunakan untuk kebanyakan bidang-bidang siap-pakai ketika backend basisdata sudah mengembalikan jenis Python yang benar, atau backend itu sendiri melakukan perubahan.

    `expression` is the same as `self`.

    Lihat Mengubah nilai menjadi obyek Python untuk penggunaan.

    Catatan

    Untuk alasan penampilan, `from_db_value` tidak diterapkan sebagai sebuah no-op pada bidang-bidang yang tidak membutuhkan itu (semua bidang-bidang Django). Karena itu anda mungkin tidak memanggil `super` dalam penentuan anda.

  Ketika menyimpan, `pre_save()` dan `get_db_prep_save()` digunakan:

  `get_db_prep_save`(value, connection)

    Same as the `get_db_prep_value()`, but called when the field value must be saved to the database. By default returns `get_db_prep_value()`.

  `pre_save`(model_instance, add)

    Method called prior to `get_db_prep_save()` to prepare the value before being saved (e.g. for `DateField.auto_now`).

    `model_instance` is the instance this field belongs to and `add` is whether the instance is being saved to the database for the first time.

    It should return the value of the appropriate attribute from `model_instance` for this field. The attribute name is in `self.attname` (this is set up by `Field`).

    Lihat Mengolah nilai sebelum menyimpan untuk penggunaan.

  Fields often receive their values as a different type, either from serialization or from forms.

  `to_python`(value)

    Converts the value into the correct Python object. It acts as the reverse of `value_to_string()`, and is also called in `clean()`.

    Lihat Mengubah nilai menjadi obyek Python untuk penggunaan.

  Besides saving to the database, the field also needs to know how to serialize its value:

  `value_from_object`(obj)

    Returns the field's value for the given model instance.

    Metode ini sering digunakan oleh `value_to_string()`.

  `value_to_string`(obj)

    Merubah `obj` menjadi sebuah string. Digunakan untuk menserialisasikan nilai dari bidang.

    Lihat Mengubah data field untuk serialisasi untuk penggunaan.

  Ketika menggunakan `model forms`, `Field` butuh mengetahui bidang formulir mana itu harus diwakili:

  `formfield`(form_class=None, choices_form_class=None, **kwargs)

    Mengembalikan `django.forms.Field` awalan dari bidang ini untuk `ModelForm`.

    Secara awalan, jika kedua `form_class` dan `choices_form_class` adalah `None`, itu menggunakan `CharField`. Jika bidang mempunyai `choices` dan `choices_form_class` tidak ditentukan, itu menggunakan `TypedChoiceField`.

    Lihat Menentukan bidang formulir untuk sebuah bidang model untuk penggunaan.

  `deconstruct`()

    Mengembalikan 4-tuple dengan informasi cukup untuk membuat kembali bidang:

    1. Nama dari bidang pada model.
    2. Jalur impor dari bidang (misalnya `"django.db.models.IntegerField"`). Ini harus versi paling ringan, jadi kurang spesifik mungkin lebih baik.
    3. Daftar dari argumen penempatan.
    4. Sebuah dict dari argumen kata kunci.

    Metode ini harus ditambahkan pada bidang sebekum 1.7 untuk memindahkan datanya menggunakan Perpindahan.

## Pencarian pendaftaran dan pengambilan

`Field` implements the lookup registration API. The API can be used to customize which lookups are available for a field class and its instances, and how lookups are fetched from a field.

Changed in Django 4.2:

Support for registering lookups on `Field` instances was added.

# Acuan atribut bidang

Every `Field` instance contains several attributes that allow introspecting its behavior. Use these attributes instead of `isinstance` checks when you need to write code that depends on a field's functionality. These attributes can be used together with the Model._meta API to narrow down a search for specific field types. Custom model fields should implement these flags.

## Atribut untuk bidang

`Field.``auto_created`

  Bendera Boolean yang menunjukkan jika bidang otomatis dibuat, seperti `OneToOneField` digunakan oleh warisan model.

`Field.``concrete`

  Bendera Boolean mengindikasikan jika bidang mempunyai kolom terkait dengan itu.

`Field.``hidden`

  Boolean flag that indicates if a field is used to back another non-hidden field's functionality (e.g. the `content_type` and `object_id` fields that make up a `GenericForeignKey`). The `hidden` flag is used to distinguish what constitutes the public subset of fields on the model from all the fields on the model.

  Catatan

  `Options.get_fields()` tidak menyertakan bidang tersembunyi secara awalan. Lewatkan di `include_hidden=True` untuk mengembalikan bidang-bidang tersembunyi di hasil.

`Field.``is_relation`

  Bendera Boolean yang menunjukkan jika sebuah bidang mengandung acuan ke satu atau lebih model untuk kegunaannya (misalnya `ForeignKey`, `ManyToManyField`, `OneToOneField`, dll.).

`Field.``model`

  Returns the model on which the field is defined. If a field is defined on a superclass of a model, `model` will refer to the superclass, not the class of the instance.

## Atribut untuk bidang dengan hubungan

These attributes are used to query for the cardinality and other details of a relation. These attribute are present on all fields; however, they will only have boolean values (rather than `None`) if the field is a relation type (`Field.is_relation=True`).

`Field.``many_to_many`

  Bendera Boolean adalah `True` jika bidang mempunyai hubungan many-to-many; `False` sebaliknya. Hanya bidang disertakan dengan Django dimana ini adalah `True` adalah `ManyToManyField`.

`Field.``many_to_one`

  Bendera Boolean adalah `True` jika bidang mempunyai hubungan many-to-one, seperti `ForeignKey`; `False` sebaliknya.

`Field.``one_to_many`

  Bendera Boolean adalah `True` jika bidang mempunyai hubungan one-to-many, seperti `GenericRelation` atau kebalikan dari `ForeignKey`; `False` sebaliknya.

`Field.``one_to_one`

  Bendera Boolean adalah `True` jika bidang mempunyai hubungan one-to-one, seperti `OneToOneField`; `False` sebaliknya.

`Field.``related_model`

  Points to the model the field relates to. For example, `Author` in `ForeignKey(Author, on_delete=models.CASCADE)`. The `related_model` for a `GenericForeignKey` is always `None`.