GraphQLError: Type Query must define one or more fields. using typegoose

Question

I try to implement typegoose on my project. I'm creating a nestjs graphql server and use mongoose to push document in my DB.

I try to use typegoose to simplify the way to implement new feature but i'm stuck on a problem to transform my mongoose "schema" with typegoose.

let's see my code

ad.ts

import { buildSchema, getModelForClass, prop } from '@typegoose/typegoose';

export class Ad{
  @prop({ required: true })
  title: String;

  @prop({ required: true })
  description: String;
}

export const AdModel = getModelForClass(Ad);
export const AdSchema = buildSchema(Ad);

ad.controller.ts

import { Body, Controller, Get, Post } from '@nestjs/common';
import { AdsService } from './ads.service';
import { Ad } from './models/ad';

@Controller('ads')
export class AdsController {
  constructor(private readonly adService: AdsService) {}

  @Get()
  async getAds(): Promise<Ad[] | null> {
    return await this.adService.findAll();
  }

  @Post()
  async create(@Body() adDto: Partial<Ad>): Promise<Ad> {
    return await this.adService.create(adDto);
  }
}

ad.service.ts

import { Injectable } from '@nestjs/common';
import { InjectModel } from '@nestjs/mongoose';
import { Ad } from './models/ad';
import { ReturnModelType } from '@typegoose/typegoose';

@Injectable()
export class AdsService {

  constructor(
    @InjectModel(Ad.name)
    private readonly adModel: ReturnModelType<typeof Ad>) {}

  async create(adDto: Partial<Ad>): Promise <Ad> {
    const createdAd = new this.adModel(adDto);
    return await createdAd.save();
  }
  async findAll(): Promise <Ad[]> {
    return await this.adModel.find().exec();
  }

}

ad.module.ts

import { Module } from '@nestjs/common';
import { AdsService } from './ads.service';
import { MongooseModule } from '@nestjs/mongoose';
import { Ad, AdSchema } from './models/ad';
import { AdsController } from './ads.controller';

@Module({
  imports:[MongooseModule.forFeature([{ name: Ad.name, schema: AdSchema }])],
  controllers: [AdsController],
  providers: [AdsService],
})
export class AdsModule {}

But i've got this error message:

The error stack trace

GraphQLError: Type Query must define one or more fields.
      at SchemaValidationContext.reportError (/home/olivier/www/other/green/back-end/graphql-server/node_modules/graphql/type/validate.js:90:19)
      at validateFields (/home/olivier/www/other/green/back-end/graphql-server/node_modules/graphql/type/validate.js:251:13)
      at validateTypes (/home/olivier/www/other/green/back-end/graphql-server/node_modules/graphql/type/validate.js:226:7)
      at validateSchema (/home/olivier/www/other/green/back-end/graphql-server/node_modules/graphql/type/validate.js:54:3)
      at graphqlImpl (/home/olivier/www/other/green/back-end/graphql-server/node_modules/graphql/graphql.js:79:62)
      at /home/olivier/www/other/green/back-end/graphql-server/node_modules/graphql/graphql.js:28:59
      at new Promise (<anonymous>)
      at Object.graphql (/home/olivier/www/other/green/back-end/graphql-server/node_modules/graphql/graphql.js:26:10)
      at Function.<anonymous> (/home/olivier/www/other/green/back-end/graphql-server/node_modules/type-graphql/dist/schema/schema-generator.js:18:52)
      at Generator.next (<anonymous>)
      at /home/olivier/www/other/green/back-end/graphql-server/node_modules/tslib/tslib.js:110:75
      at new Promise (<anonymous>)
      at Object.__awaiter (/home/olivier/www/other/green/back-end/graphql-server/node_modules/tslib/tslib.js:106:16)
      at Function.generateFromMetadata (/home/olivier/www/other/green/back-end/graphql-server/node_modules/type-graphql/dist/schema/schema-generator.js:15:24)
      at /home/olivier/www/other/green/back-end/graphql-server/node_modules/type-graphql/dist/utils/buildSchema.js:11:65
      at Generator.next (<anonymous>) {
    message: 'Type Query must define one or more fields.'
  }
]
(node:1828) UnhandledPromiseRejectionWarning: Error: Generating schema error
    at Function.<anonymous> (/home/olivier/www/other/green/back-end/graphql-server/node_modules/type-graphql/dist/schema/schema-generator.js:20:27)
    at Generator.next (<anonymous>)
    at fulfilled (/home/olivier/www/other/green/back-end/graphql-server/node_modules/tslib/tslib.js:107:62)
    at processTicksAndRejections (internal/process/task_queues.js:93:5)
(node:1828) UnhandledPromiseRejectionWarning: Unhandled promise rejection. This error originated either by throwing inside of an async function without a catch block, or by rejecting a promise which was not handled with .catch(). (rejection id: 1)
(node:1828) [DEP0018] DeprecationWarning: Unhandled promise rejections are deprecated. In the future, promise rejections that are not handled will terminate the Node.js process with a non-zero exit code.

Answer 1

I had this error as well with this code:

const schema = await buildSchema({
  resolvers: [`${__dirname}/resolvers/*.ts`],
  emitSchemaFile: true,
  globalMiddlewares: [TypegooseMiddleware],
});

Fixed:

const schema = await buildSchema({
  resolvers: [`${__dirname}/resolvers/*.{ts,js}`],
  emitSchemaFile: true,
  globalMiddlewares: [TypegooseMiddleware],
});

Answer 2

I guess it's nothing to do with Typegoose. Have you defined any Graphql type or queries? If you added GraphQLModule to your app's module, you need to have a proper .graphql file which should has at least a Query type.