time-table

A PostgreSQL-backed @imqueue RPC microservice that manages the washing schedule — reservations, the working-hours configuration, and the rule that keeps a car from being double-booked.

It stores reservations as time ranges (tstzrange) and exposes the station's options (opening hours, number of boxes, washing types and their durations). It never speaks HTTP; every method is exposed over the @imqueue/rpc Redis message queue and consumed by the gateways (api, api-rest).

Persistence goes through @imqueue/pg-sequelize, the framework's Sequelize toolkit — see Data layer.

This repo is one piece of the imqueue-sandbox tutorial — a complete car-wash booking app built from independent RPC microservices that communicate over a Redis-backed message queue.

The backend services are transport-agnostic: two interchangeable gateways and two independent front-ends prove the same fleet can be fronted by completely different API styles without changing a single service.

Exposed by the TimeTable service (src/TimeTable.ts) via @expose():

A reservation is { id, carId, userId, type, duration }, where type is fast / std / full and duration is a [start, end) timestamp range. The default station options are 08:00–21:00, 4 boxes, and washing types fast (30 min), std (45 min), full (60 min).

reserve is guarded at the database level by a unique index (car_duplicate_idx) on (carId, day-of-duration, coalesced deletedAt): a car may hold at most one active reservation per calendar day. A PostgreSQL unique-violation (23505) is translated into the friendly error "Time for given car has been already reserved at this date!". Reservations are paranoid (soft-deleted), so cancelling frees the slot again. The schema (including the index and a range_date() helper function) is created automatically on start via orm.sync() + migration.

The ORM stack comes from @imqueue/pg-sequelize, which is the single import surface for it — models import Table, Column, DataType and the rest from there rather than from sequelize-typescript directly.

Two details worth knowing:

• Models live in their own directory. database() walks dbConfig.modelsPath for compiled .js files and takes from each the export named after the file, so src/orm/models/ holds one model per file and nothing else (index.js there would hand Sequelize undefined).
• Indices are declared on the columns. The GiST index that makes range containment — the one query every read runs — use an index is @ColumnIndex({ method: IndexMethod.GIST }) on duration. The double-booking guard is a key of one column plus two expressions, which is more than @ColumnIndex can express, so that one is an explicit statement in migrate().

Reads build their statement with query.autoQuery(), which narrows the SELECT to the columns the caller asked for — and drops names that are not columns, falling back to the primary key — so a gateway passing its GraphQL selection set through gets exactly those columns and nothing else.

Environment variables (loaded from an optional .env via process.loadEnvFile()):

Development mode (rebuilds and restarts on change):

npm run dev

Production mode:

npm start

Both start the service under the imqueue label time-table. Requires a reachable PostgreSQL at DB_CONN_STR and Redis at IMQ_REDIS.

ISC License