feat: allow interfaces to implement other interfaces (#496)

closes #389

src/builder.ts

@@ -52,16 +52,12 @@ import { NexusExtendInputTypeConfig, NexusExtendInputTypeDef } from './definitio
 import { NexusExtendTypeConfig, NexusExtendTypeDef } from './definitions/extendType'
 import { NexusInputObjectTypeConfig } from './definitions/inputObjectType'
 import {
+  Implemented,
   InterfaceDefinitionBlock,
   NexusInterfaceTypeConfig,
   NexusInterfaceTypeDef,
 } from './definitions/interfaceType'
-import {
-  Implemented,
-  NexusObjectTypeConfig,
-  NexusObjectTypeDef,
-  ObjectDefinitionBlock,
-} from './definitions/objectType'
+import { NexusObjectTypeConfig, NexusObjectTypeDef, ObjectDefinitionBlock } from './definitions/objectType'
 import { NexusScalarExtensions, NexusScalarTypeConfig } from './definitions/scalarType'
 import { NexusUnionTypeConfig, UnionDefinitionBlock, UnionMembers } from './definitions/unionType'
 import {
@@ -701,6 +697,51 @@ export class SchemaBuilder {
     })
   }
 
+  checkForInterfaceCircularDependencies() {
+    const interfaces: Record<string, NexusInterfaceTypeConfig<any>> = {}
+    Object.keys(this.pendingTypeMap)
+      .map((key) => this.pendingTypeMap[key])
+      .filter(isNexusInterfaceTypeDef)
+      .forEach((type) => {
+        interfaces[type.name] = type.value
+      })
+    const alreadyChecked: Record<string, boolean> = {}
+    function walkType(obj: NexusInterfaceTypeConfig<any>, path: string[], visited: Record<string, boolean>) {
+      if (alreadyChecked[obj.name]) {
+        return
+      }
+      if (visited[obj.name]) {
+        if (obj.name === path[path.length - 1]) {
+          throw new Error(`GraphQL Nexus: Interface ${obj.name} can't implement itself`)
+        } else {
+          throw new Error(
+            `GraphQL Nexus: Interface circular dependency detected ${[
+              ...path.slice(path.lastIndexOf(obj.name)),
+              obj.name,
+            ].join(' -> ')}`
+          )
+        }
+      }
+      const definitionBlock = new InterfaceDefinitionBlock({
+        typeName: obj.name,
+        addInterfaces: (i) =>
+          i.forEach((config) => {
+            const name = typeof config === 'string' ? config : config.value.name
+            walkType(interfaces[name], [...path, obj.name], { ...visited, [obj.name]: true })
+          }),
+        setResolveType: () => {},
+        addField: () => {},
+        addDynamicOutputMembers: () => {},
+        warn: () => {},
+      })
+      obj.definition(definitionBlock)
+      alreadyChecked[obj.name] = true
+    }
+    Object.keys(interfaces).forEach((name) => {
+      walkType(interfaces[name], [], {})
+    })
+  }
+
   buildNexusTypes() {
     // If Query isn't defined, set it to null so it falls through to "missingType"
     if (!this.pendingTypeMap.Query) {
@@ -758,6 +799,7 @@ export class SchemaBuilder {
     this.createSchemaExtension()
     this.walkTypes()
     this.beforeBuildTypes()
+    this.checkForInterfaceCircularDependencies()
     this.buildNexusTypes()
     return {
       finalConfig: this.config,
@@ -824,19 +866,9 @@ export class SchemaBuilder {
     }
     const objectTypeConfig: NexusGraphQLObjectTypeConfig = {
       name: config.name,
-      interfaces: () => interfaces.map((i) => this.getInterface(i)),
+      interfaces: () => this.buildInterfaceList(interfaces),
       description: config.description,
-      fields: () => {
-        const allInterfaces = interfaces.map((i) => this.getInterface(i))
-        const interfaceConfigs = allInterfaces.map((i) => i.toConfig())
-        const interfaceFieldsMap: GraphQLFieldConfigMap<any, any> = {}
-        interfaceConfigs.forEach((i) => {
-          Object.keys(i.fields).forEach((iFieldName) => {
-            interfaceFieldsMap[iFieldName] = i.fields[iFieldName]
-          })
-        })
-        return this.buildOutputFields(fields, objectTypeConfig, interfaceFieldsMap)
-      },
+      fields: () => this.buildOutputFields(fields, objectTypeConfig, this.buildInterfaceFields(interfaces)),
       extensions: {
         nexus: new NexusObjectTypeExtension(config),
       },
@@ -848,9 +880,11 @@ export class SchemaBuilder {
     const { name, description } = config
     let resolveType: AbstractTypeResolver<string> | undefined
     const fields: NexusOutputFieldDef[] = []
+    const interfaces: Implemented[] = []
     const definitionBlock = new InterfaceDefinitionBlock({
       typeName: config.name,
       addField: (field) => fields.push(field),
+      addInterfaces: (interfaceDefs) => interfaces.push(...interfaceDefs),
       setResolveType: (fn) => (resolveType = fn),
       addDynamicOutputMembers: (block, isList) => this.addDynamicOutputMembers(block, isList, 'build'),
       warn: consoleWarn,
@@ -870,9 +904,11 @@ export class SchemaBuilder {
     }
     const interfaceTypeConfig: NexusGraphQLInterfaceTypeConfig = {
       name,
+      interfaces: () => this.buildInterfaceList(interfaces),
       resolveType,
       description,
-      fields: () => this.buildOutputFields(fields, interfaceTypeConfig, {}),
+      fields: () =>
+        this.buildOutputFields(fields, interfaceTypeConfig, this.buildInterfaceFields(interfaces)),
       extensions: {
         nexus: new NexusInterfaceTypeExtension(config),
       },
@@ -1013,6 +1049,26 @@ export class SchemaBuilder {
     return unionMembers
   }
 
+  protected buildInterfaceList(interfaces: (string | NexusInterfaceTypeDef<any>)[]) {
+    const list: GraphQLInterfaceType[] = []
+    interfaces.forEach((i) => {
+      const type = this.getInterface(i)
+      list.push(type, ...type.getInterfaces())
+    })
+    return list
+  }
+
+  protected buildInterfaceFields(interfaces: (string | NexusInterfaceTypeDef<any>)[]) {
+    const interfaceFieldsMap: GraphQLFieldConfigMap<any, any> = {}
+    interfaces.forEach((i) => {
+      const config = this.getInterface(i).toConfig()
+      Object.keys(config.fields).forEach((field) => {
+        interfaceFieldsMap[field] = config.fields[field]
+      })
+    })
+    return interfaceFieldsMap
+  }
+
   protected buildOutputFields(
     fields: NexusOutputFieldDef[],
     typeConfig: NexusGraphQLInterfaceTypeConfig | NexusGraphQLObjectTypeConfig,
@@ -1380,6 +1436,13 @@ export class SchemaBuilder {
   protected walkInterfaceType(obj: NexusInterfaceTypeConfig<any>) {
     const definitionBlock = new InterfaceDefinitionBlock({
       typeName: obj.name,
+      addInterfaces: (i) => {
+        i.forEach((j) => {
+          if (typeof j !== 'string') {
+            this.addType(j)
+          }
+        })
+      },
       setResolveType: () => {},
       addField: (f) => this.maybeTraverseOutputFieldType(f),
       addDynamicOutputMembers: (block, isList) => this.addDynamicOutputMembers(block, isList, 'walk'),

src/definitions/definitionBlocks.ts

@@ -1,13 +1,5 @@
 import { GraphQLFieldResolver } from 'graphql'
-import {
-  AbstractTypeResolver,
-  AllInputTypes,
-  FieldResolver,
-  GetGen,
-  GetGen3,
-  HasGen3,
-  NeedsResolver,
-} from '../typegenTypeHelpers'
+import { AllInputTypes, FieldResolver, GetGen, GetGen3, HasGen3, NeedsResolver } from '../typegenTypeHelpers'
 import { ArgsRecord } from './args'
 import { AllNexusInputTypeDefs, AllNexusOutputTypeDefs } from './wrapping'
 import { BaseScalars } from './_types'
@@ -285,7 +277,3 @@ export class InputDefinitionBlock<TypeName extends string> {
     return config
   }
 }
-
-export interface AbstractOutputDefinitionBuilder<TypeName extends string> extends OutputDefinitionBuilder {
-  setResolveType(fn: AbstractTypeResolver<TypeName>): void
-}

src/definitions/interfaceType.ts

@@ -1,8 +1,10 @@
 import { assertValidName } from 'graphql'
-import { AbstractTypeResolver } from '../typegenTypeHelpers'
-import { AbstractOutputDefinitionBuilder, OutputDefinitionBlock } from './definitionBlocks'
+import { AbstractTypeResolver, GetGen } from '../typegenTypeHelpers'
+import { OutputDefinitionBlock, OutputDefinitionBuilder } from './definitionBlocks'
 import { NexusTypes, NonNullConfig, RootTypingDef, withNexusSymbol } from './_types'
 
+export type Implemented = GetGen<'interfaceNames'> | NexusInterfaceTypeDef<any>
+
 export type NexusInterfaceTypeConfig<TypeName extends string> = {
   name: TypeName
 
@@ -31,8 +33,13 @@ export type NexusInterfaceTypeConfig<TypeName extends string> = {
   rootTyping?: RootTypingDef
 }
 
+export interface InterfaceDefinitionBuilder<TypeName extends string> extends OutputDefinitionBuilder {
+  setResolveType(fn: AbstractTypeResolver<TypeName>): void
+  addInterfaces(toAdd: Implemented[]): void
+}
+
 export class InterfaceDefinitionBlock<TypeName extends string> extends OutputDefinitionBlock<TypeName> {
-  constructor(protected typeBuilder: AbstractOutputDefinitionBuilder<TypeName>) {
+  constructor(protected typeBuilder: InterfaceDefinitionBuilder<TypeName>) {
     super(typeBuilder)
   }
   /**
@@ -41,6 +48,12 @@ export class InterfaceDefinitionBlock<TypeName extends string> extends OutputDef
   resolveType(fn: AbstractTypeResolver<TypeName>) {
     this.typeBuilder.setResolveType(fn)
   }
+  /**
+   * @param interfaceName
+   */
+  implements(...interfaceName: Array<Implemented>) {
+    this.typeBuilder.addInterfaces(interfaceName)
+  }
 }
 
 export class NexusInterfaceTypeDef<TypeName extends string> {

src/definitions/objectType.ts

@@ -1,11 +1,9 @@
 import { assertValidName } from 'graphql'
-import { FieldResolver, GetGen } from '../typegenTypeHelpers'
+import { FieldResolver } from '../typegenTypeHelpers'
 import { OutputDefinitionBlock, OutputDefinitionBuilder } from './definitionBlocks'
-import { NexusInterfaceTypeDef } from './interfaceType'
+import { Implemented } from './interfaceType'
 import { NexusTypes, NonNullConfig, Omit, RootTypingDef, withNexusSymbol } from './_types'
 
-export type Implemented = GetGen<'interfaceNames'> | NexusInterfaceTypeDef<any>
-
 export interface FieldModification<TypeName extends string, FieldName extends string> {
   /**
    * The description to annotate the GraphQL SDL

tests/__snapshots__/interfaceType.spec.ts.snap

@@ -11,6 +11,23 @@ Object {
 }
 `;
 
+exports[`interfaceType can extend other interfaces 1`] = `
+Object {
+  "data": Object {
+    "dog": Object {
+      "breed": "Puli",
+      "classification": "Canis familiaris",
+      "owner": "Mark",
+      "type": "Animal",
+    },
+  },
+}
+`;
+
+exports[`interfaceType can not implement itself 1`] = `"GraphQL Nexus: Interface Node can't implement itself"`;
+
+exports[`interfaceType detects circular dependencies 1`] = `"GraphQL Nexus: Interface circular dependency detected NodeA -> NodeC -> NodeB -> NodeA"`;
+
 exports[`interfaceType logs error when resolveType is not provided for an interface 1`] = `
 Array [
   [Error: Missing resolveType for the Node interface. Be sure to add one in the definition block for the type, or t.resolveType(() => null) if you don't want or need to implement.],

tests/interfaceType.spec.ts

@@ -45,6 +45,119 @@ describe('interfaceType', () => {
       )
     ).toMatchSnapshot()
   })
+  it('can extend other interfaces', async () => {
+    const schema = makeSchema({
+      types: [
+        interfaceType({
+          name: 'LivingOrganism',
+          definition(t) {
+            t.string('type')
+            t.resolveType(() => null)
+          },
+        }),
+        interfaceType({
+          name: 'Animal',
+          definition(t) {
+            t.implements('LivingOrganism')
+            t.string('classification')
+            t.resolveType(() => null)
+          },
+        }),
+        interfaceType({
+          name: 'Pet',
+          definition(t) {
+            t.implements('Animal')
+            t.string('owner')
+            t.resolveType(() => null)
+          },
+        }),
+        objectType({
+          name: 'Dog',
+          definition(t) {
+            t.implements('Pet')
+            t.string('breed')
+          },
+        }),
+        queryField('dog', {
+          type: 'Dog',
+          resolve: () => ({
+            type: 'Animal',
+            classification: 'Canis familiaris',
+            owner: 'Mark',
+            breed: 'Puli',
+          }),
+        }),
+      ],
+      outputs: {
+        schema: path.join(__dirname, 'interfaceTypeTest.graphql'),
+        typegen: false,
+      },
+      shouldGenerateArtifacts: false,
+    })
+    expect(
+      await graphql(
+        schema,
+        `
+          {
+            dog {
+              type
+              classification
+              owner
+              breed
+            }
+          }
+        `
+      )
+    ).toMatchSnapshot()
+  })
+  it('can not implement itself', async () => {
+    expect(() =>
+      makeSchema({
+        types: [
+          interfaceType({
+            name: 'Node',
+            definition(t) {
+              t.id('id')
+              t.implements('Node')
+            },
+          }),
+        ],
+        outputs: false,
+        shouldGenerateArtifacts: false,
+      })
+    ).toThrowErrorMatchingSnapshot()
+  })
+  it('detects circular dependencies', async () => {
+    expect(() =>
+      makeSchema({
+        types: [
+          interfaceType({
+            name: 'NodeA',
+            definition(t) {
+              t.id('a')
+              t.implements('NodeC')
+            },
+          }),
+          interfaceType({
+            name: 'NodeB',
+            definition(t) {
+              t.id('b')
+              t.implements('NodeA')
+            },
+          }),
+          interfaceType({
+            name: 'NodeC',
+            definition(t) {
+              t.id('c')
+              t.implements('NodeB')
+            },
+          }),
+        ],
+        outputs: false,
+        shouldGenerateArtifacts: false,
+      })
+    ).toThrowErrorMatchingSnapshot()
+  })
   it('logs error when resolveType is not provided for an interface', async () => {
     const spy = jest.spyOn(console, 'error').mockImplementation()
     makeSchema({