Nestjs define GraphQL Object type got this error: Schema must contain uniquely named types but contains multiple types named "Address"

Question

I use Nestjs & GraphQL for backend development, when I define model class (code first), I got following error: Schema must contain uniquely named types but contains multiple types named "Address". Following is my Reader model file:

@ObjectType()
class Address {
  @Field()
  homeAddress: string;
  @Field()
  province: string;
  @Field()
  postcode: string;
}

@ObjectType()
class FavouriteBook {
  @Field()
  bookID: string;
  @Field()
  createDate: Date;
}

@ObjectType()
export class ReaderProfile {
  @Field()
  _id: string;
  @Field()
  firstName: string;
  @Field()
  lastName: string;
  @Field()
  gender: string;
  @Field()
  birthday: Date;
  @Field()
  address?: Address;
  @Field()
  postcode: string;
  @Field(type => Int)
  readTimes: number;
  @Field(type => Int)
  readDuration: number;
  @Field(type => Int)
  score: number;
  @Field()
  securityQuestion: string;
  @Field()
  securityAnswer: string;
}

@ObjectType()
export class ReaderReadHistory {
  @Field()
  _id: string;
  @Field()
  bookID: string;
  @Field(type => Int)
  currentPage: number;
  @Field()
  startTime: Date;
  @Field()
  lastReadTime: Date;
  @Field(type => Int)
  readTimes: number;
  @Field(type => Int)
  readDuration: number;
}

@ObjectType()
export class Reader {
  @Field()
  _id: string;
  @Field()
  username: string;
  @Field()
  password: string;
  @Field()
  email: string;
  @Field()
  registerDate: Date;
  @Field()
  isActive: boolean;
  @Field({ nullable: true })
  currentRefreshToken?: string;
  @Field(type => ReaderProfile)
  readerProfile: ReaderProfile;
  @Field(type => [FavouriteBook])
  favouriteBook: FavouriteBook[];
  @Field(type => [ReaderReadHistory])
  readHistory: ReaderReadHistory[];
}

And this is my GraghQL configuration in app module: (code first)

GraphQLModule.forRoot({
      autoSchemaFile: join(process.cwd(), 'src/schema.gql'),
      cors: false,
      sortSchema: true,
      context: ({ req }) => ({ req }),
    }),

Does anyone know how to fix this? Thanks a lot!

Answer 1

Eventually I did not find reason, and I changed coding to schema first which works well as expected. Hopefully this help for those have same issue but can't fixed with code first approach, try schema first. Also I found schema first approach has less boil-plates, especially you can use separate auto generate function (refer to following) to generate all the type script interfaces in one file, there is pretty helpful.

import { GraphQLDefinitionsFactory } from '@nestjs/graphql';
import { join } from 'path';

const definitionsFactory = new GraphQLDefinitionsFactory();
definitionsFactory.generate({
  typePaths: ['./src/**/*.graphql'],
  path: join(process.cwd(), 'src/graphql.ts'),
});