graphql-java · bbakerman · Aug 3, 2021 · Jul 30, 2021
diff --git a/src/main/java/graphql/schema/FieldCoordinates.java b/src/main/java/graphql/schema/FieldCoordinates.java
@@ -78,7 +78,7 @@ public int hashCode() {
 
     @Override
     public String toString() {
-        return typeName + ':' + fieldName + '\'';
+        return typeName + '.' + fieldName;
     }
 
     /**

diff --git a/src/main/java/graphql/schema/GraphQLSchema.java b/src/main/java/graphql/schema/GraphQLSchema.java
@@ -293,6 +293,30 @@ public GraphQLObjectType getObjectType(String typeName) {
         return (GraphQLObjectType) graphQLType;
     }
 
+    public GraphQLFieldDefinition getFieldDefinition(FieldCoordinates fieldCoordinates) {
+        String fieldName = fieldCoordinates.getFieldName();
+        if (fieldCoordinates.isSystemCoordinates()) {
+            if (fieldName.equals(this.getIntrospectionSchemaFieldDefinition().getName())) {
+                return this.getIntrospectionSchemaFieldDefinition();
+            }
+            if (fieldName.equals(this.getIntrospectionTypeFieldDefinition().getName())) {
+                return this.getIntrospectionTypeFieldDefinition();
+            }
+            if (fieldName.equals(this.getIntrospectionTypenameFieldDefinition().getName())) {
+                return this.getIntrospectionTypenameFieldDefinition();
+            }
+            return Assert.assertShouldNeverHappen("The system field name %s is unknown", fieldName);
+        }
+        String typeName = fieldCoordinates.getTypeName();
+        GraphQLType graphQLType = getType(typeName);
+        if (graphQLType != null) {
+            assertTrue(graphQLType instanceof GraphQLFieldsContainer,
+                    () -> String.format("You have asked for named type '%s' but its not GraphQLFieldsContainer but rather a '%s'", typeName, graphQLType.getClass().getName()));
+            return ((GraphQLFieldsContainer) graphQLType).getFieldDefinition(fieldName);
+        }
+        return null;
+    }
+
     public Map<String, GraphQLNamedType> getTypeMap() {
         return typeMap;
     }

diff --git a/src/test/groovy/graphql/schema/GraphQLSchemaTest.groovy b/src/test/groovy/graphql/schema/GraphQLSchemaTest.groovy
@@ -272,4 +272,56 @@ class GraphQLSchemaTest extends Specification {
         newDF !== nameDF
         newDF instanceof PropertyDataFetcher // defaulted in
     }
+
+    def "can get by field co-ordinate"() {
+        when:
+        def fieldDef = starWarsSchema.getFieldDefinition(FieldCoordinates.coordinates("QueryType", "hero"))
+
+        then:
+        fieldDef.name == "hero"
+        (fieldDef.type as GraphQLInterfaceType).getName() == "Character"
+
+        when:
+        fieldDef = starWarsSchema.getFieldDefinition(FieldCoordinates.coordinates("X", "hero"))
+
+        then:
+        fieldDef == null
+
+        when:
+        fieldDef = starWarsSchema.getFieldDefinition(FieldCoordinates.coordinates("QueryType", "X"))
+
+        then:
+        fieldDef == null
+
+        when:
+        starWarsSchema.getFieldDefinition(FieldCoordinates.coordinates("Episode", "JEDI"))
+
+        then:
+        thrown(AssertException)
+
+        when:
+        fieldDef = starWarsSchema.getFieldDefinition(FieldCoordinates.systemCoordinates("__typename"))
+
+        then:
+        fieldDef == starWarsSchema.getIntrospectionTypenameFieldDefinition()
+
+        when:
+        fieldDef = starWarsSchema.getFieldDefinition(FieldCoordinates.systemCoordinates("__type"))
+
+        then:
+        fieldDef == starWarsSchema.getIntrospectionTypeFieldDefinition()
+
+        when:
+        fieldDef = starWarsSchema.getFieldDefinition(FieldCoordinates.systemCoordinates("__schema"))
+
+        then:
+        fieldDef == starWarsSchema.getIntrospectionSchemaFieldDefinition()
+
+        when:
+        starWarsSchema.getFieldDefinition(FieldCoordinates.systemCoordinates("__junk"))
+
+        then:
+        thrown(AssertException)
+
+    }
 }