Feat: Expose user-defined directives via introspection

src/__tests__/starWarsIntrospection-test.js

@@ -45,6 +45,7 @@ describe('Star Wars Introspection Tests', () => {
             { name: '__EnumValue' },
             { name: '__Directive' },
             { name: '__DirectiveLocation' },
+            { name: '__AppliedDirective' },
           ],
         },
       });

src/index.d.ts

@@ -65,6 +65,7 @@ export {
   __Schema,
   __Directive,
   __DirectiveLocation,
+  __AppliedDirective,
   __Type,
   __Field,
   __InputValue,

src/type/__tests__/introspection-test.js

@@ -8,6 +8,18 @@ import { graphqlSync } from '../../graphql';
 
 describe('Introspection', () => {
   it('executes an introspection query', () => {
+    // TODO Include custom directives in the introspection schema
+    // const schema = buildSchema(`
+    //   directive @foo(bar: Int) on FIELD_DEFINITION
+
+    //   type SomeObject {
+    //     someField: String @foo(bar: "some value")
+    //   }
+
+    //   schema {
+    //     query: SomeObject
+    //   }
+    // `);
     const schema = buildSchema(`
       type SomeObject {
         someField: String
@@ -173,6 +185,30 @@ describe('Introspection', () => {
                   isDeprecated: false,
                   deprecationReason: null,
                 },
+
+                {
+                  name: 'appliedDirectives',
+                  args: [],
+                  type: {
+                    kind: 'NON_NULL',
+                    name: null,
+                    ofType: {
+                      kind: 'LIST',
+                      name: null,
+                      ofType: {
+                        kind: 'NON_NULL',
+                        name: null,
+                        ofType: {
+                          kind: 'OBJECT',
+                          name: '__AppliedDirective',
+                          ofType: null,
+                        },
+                      },
+                    },
+                  },
+                  isDeprecated: false,
+                  deprecationReason: null,
+                },
               ],
               inputFields: null,
               interfaces: [],
@@ -892,6 +928,55 @@ describe('Introspection', () => {
               ],
               possibleTypes: null,
             },
+            {
+              kind: 'OBJECT',
+              name: '__AppliedDirective',
+              specifiedByUrl: null,
+              fields: [
+                {
+                  name: 'name',
+                  args: [],
+                  type: {
+                    kind: 'NON_NULL',
+                    name: null,
+                    ofType: {
+                      kind: 'SCALAR',
+                      name: 'String',
+                      ofType: null,
+                    },
+                  },
+                  isDeprecated: false,
+                  deprecationReason: null,
+                },
+                {
+                  name: 'args',
+                  args: [],
+                  type: {
+                    kind: 'NON_NULL',
+                    name: null,
+                    ofType: {
+                      kind: 'LIST',
+                      name: null,
+                      ofType: {
+                        kind: 'NON_NULL',
+                        name: null,
+                        ofType: {
+                          kind: 'OBJECT',
+                          name: '__InputValue',
+                          ofType: null,
+                        },
+                      },
+                    },
+                  },
+                  isDeprecated: false,
+                  deprecationReason: null,
+                },
+              ],
+              inputFields: null,
+              interfaces: [],
+              enumValues: null,
+              possibleTypes: null,
+            },
           ],
           directives: [
             {

src/type/__tests__/schema-test.js

@@ -302,6 +302,7 @@ describe('Type System: Schema', () => {
       '__EnumValue',
       '__Directive',
       '__DirectiveLocation',
+      '__AppliedDirective',
     ]);
 
     // Also check that this order is stable

src/type/index.d.ts

@@ -155,6 +155,7 @@ export {
   __Schema,
   __Directive,
   __DirectiveLocation,
+  __AppliedDirective,
   __Type,
   __Field,
   __InputValue,

src/type/index.js

@@ -105,6 +105,7 @@ export {
   __Schema,
   __Directive,
   __DirectiveLocation,
+  __AppliedDirective,
   __Type,
   __Field,
   __InputValue,

src/type/introspection.d.ts

@@ -8,6 +8,7 @@ import {
 export const __Schema: GraphQLObjectType;
 export const __Directive: GraphQLObjectType;
 export const __DirectiveLocation: GraphQLEnumType;
+export const __AppliedDirective: GraphQLObjectType;
 export const __Type: GraphQLObjectType;
 export const __Field: GraphQLObjectType;
 export const __InputValue: GraphQLObjectType;

src/type/introspection.js

@@ -67,12 +67,21 @@ export const __Schema: GraphQLObjectType = new GraphQLObjectType({
         resolve: (schema) => schema.getSubscriptionType(),
       },
       directives: {
-        description: 'A list of all directives supported by this server.',
+        description:
+          'A list of all built in directives supported by this server.',
         type: new GraphQLNonNull(
           new GraphQLList(new GraphQLNonNull(__Directive)),
         ),
         resolve: (schema) => schema.getDirectives(),
       },
+      appliedDirectives: {
+        description:
+          'A list of all custom directives supported by this server.',
+        type: new GraphQLNonNull(
+          new GraphQLList(new GraphQLNonNull(__AppliedDirective)),
+        ),
+        resolve: (schema) => schema.getAppliedDirectives(),
+      },
     }: GraphQLFieldConfigMap<GraphQLSchema, mixed>),
 });
 
@@ -193,6 +202,25 @@ export const __DirectiveLocation: GraphQLEnumType = new GraphQLEnumType({
   },
 });
 
+export const __AppliedDirective: GraphQLObjectType = new GraphQLObjectType({
+  name: '__AppliedDirective',
+  description:
+    'An AppliedDirective is a custom directive.  TODO flesh out description',
+  fields: () =>
+    ({
+      name: {
+        type: new GraphQLNonNull(GraphQLString),
+        resolve: (appliedDirective) => appliedDirective.name,
+      },
+      args: {
+        type: new GraphQLNonNull(
+          new GraphQLList(new GraphQLNonNull(__InputValue)),
+        ),
+        resolve: (appliedDirective) => appliedDirective.args,
+      },
+    }: GraphQLFieldConfigMap<GraphQLDirective, mixed>),
+});
+
 export const __Type: GraphQLObjectType = new GraphQLObjectType({
   name: '__Type',
   description:
@@ -533,6 +561,8 @@ export const introspectionTypes: $ReadOnlyArray<GraphQLNamedType> = Object.freez
     __Schema,
     __Directive,
     __DirectiveLocation,
+    __AppliedDirective,
+    // __DirectiveArgument,
     __Type,
     __Field,
     __InputValue,

src/type/schema.js

@@ -127,6 +127,7 @@ export class GraphQLSchema {
   _mutationType: ?GraphQLObjectType;
   _subscriptionType: ?GraphQLObjectType;
   _directives: $ReadOnlyArray<GraphQLDirective>;
+  _appliedDirectives: $ReadOnlyArray<GraphQLDirective>;
   _typeMap: TypeMap;
   _subTypeMap: ObjMap<ObjMap<boolean>>;
   _implementationsMap: ObjMap<{|
@@ -165,6 +166,8 @@ export class GraphQLSchema {
     // Provide specified directives (e.g. @include and @skip) by default.
     this._directives = config.directives ?? specifiedDirectives;
 
+    this._appliedDirectives = config.appliedDirectives || [];
+
     // To preserve order of user-provided types, we add first to add them to
     // the set of "collected" types, so `collectReferencedTypes` ignore them.
     const allReferencedTypes: Set<GraphQLNamedType> = new Set(config.types);
@@ -323,6 +326,10 @@ export class GraphQLSchema {
     return this._directives;
   }
 
+  getAppliedDirectives(): $ReadOnlyArray<GraphQLDirective> {
+    return this._appliedDirectives;
+  }
+
   getDirective(name: string): ?GraphQLDirective {
     return this.getDirectives().find((directive) => directive.name === name);
   }
@@ -368,6 +375,7 @@ export type GraphQLSchemaConfig = {|
   subscription?: ?GraphQLObjectType,
   types?: ?Array<GraphQLNamedType>,
   directives?: ?Array<GraphQLDirective>,
+  appliedDirectives?: ?Array<GraphQLDirective>,
   extensions?: ?ReadOnlyObjMapLike<mixed>,
   astNode?: ?SchemaDefinitionNode,
   extensionASTNodes?: ?$ReadOnlyArray<SchemaExtensionNode>,

src/utilities/__tests__/printSchema-test.js

@@ -663,8 +663,11 @@ describe('Type System Printer', () => {
         """
         subscriptionType: __Type
 
-        """A list of all directives supported by this server."""
+        """A list of all built in directives supported by this server."""
         directives: [__Directive!]!
+
+        """A list of all custom directives supported by this server."""
+        appliedDirectives: [__AppliedDirective!]!
       }
 
       """
@@ -830,6 +833,12 @@ describe('Type System Printer', () => {
         """Location adjacent to an input object field definition."""
         INPUT_FIELD_DEFINITION
       }
+
+      """An AppliedDirective is a custom directive.  TODO flesh out description"""
+      type __AppliedDirective {
+        name: String!
+        args: [__InputValue!]!
+      }
     `);
   });
 });