Merge pull request #2276 from exarus/fix-list-field-in-intersection

fix(graphql): Support @field of list type in IntersectionType

Author: kamilmysliwiec

packages/graphql/lib/type-helpers/intersection-type.helper.ts

@@ -1,4 +1,5 @@
 import { Type } from '@nestjs/common';
+import { isFunction } from '@nestjs/common/utils/shared.utils';
 import {
   inheritPropertyInitializers,
   inheritTransformationMetadata,
@@ -37,6 +38,14 @@ export function IntersectionType<A, B>(
   inheritTransformationMetadata(classBRef, IntersectionObjectType);
 
   fields.forEach((item) => {
+    if (isFunction(item.typeFn)) {
+      /**
+       * Execute type function eagarly to update the type options object (before "clone" operation)
+       * when the passed function (e.g., @Field(() => Type)) lazily returns an array.
+       */
+      item.typeFn();
+    }
+
     Field(item.typeFn, { ...item.options })(
       IntersectionObjectType.prototype,
       item.name,

packages/graphql/tests/plugin/type-helpers/intersection-type.helper.spec.ts

@@ -29,6 +29,9 @@ describe('IntersectionType', () => {
 
     firstName?: string;
 
+    @Field(() => [String])
+    hobbies?: string[];
+
     static [METADATA_FACTORY_NAME]() {
       return {
         firstName: { nullable: true, type: () => String },
@@ -41,11 +44,13 @@ describe('IntersectionType', () => {
   it('should inherit all fields from two types', () => {
     const prototype = Object.getPrototypeOf(UpdateUserDto);
     const { fields } = getFieldsAndDecoratorForType(prototype);
-    expect(fields.length).toEqual(4);
+    expect(fields.length).toEqual(5);
     expect(fields[0].name).toEqual('login');
     expect(fields[1].name).toEqual('password');
     expect(fields[2].name).toEqual('lastName');
-    expect(fields[3].name).toEqual('firstName');
+    expect(fields[3].name).toEqual('hobbies');
+    expect(fields[3].options).toEqual({ isArray: true, arrayDepth: 1 });
+    expect(fields[4].name).toEqual('firstName');
     expect(fields[0].directives.length).toEqual(1);
     expect(fields[0].directives).toContainEqual({
       fieldName: 'login',