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Example

Let's create a simple todo-item graphql example.

Set up a new nest app​

npm i -g @nestjs/cli
nest new nestjs-query-getting-started

Install Dependencies​

Install your packages.

note

Be sure to install the correct ORM package!

Install extra dependencies for the example.

npm i pg apollo-server-express

Generate the Module​

From the root of your project run:

npx nest g mo todo-item

Create the Entity​

From the root of your project run:

npx nest g cl todo-item.entity todo-item --flat

Now lets fill out the entity.

Add the following to src/todo-item/todo-item.entity.ts.

todo-item/todo-item.entity.ts
import {
  Column,
  CreateDateColumn,
  Entity,
  PrimaryGeneratedColumn,
  UpdateDateColumn,
} from 'typeorm';

@Entity()
export class TodoItemEntity {
  @PrimaryGeneratedColumn()
  id!: string;

  @Column()
  title!: string;

  @Column()
  completed!: boolean;

  @CreateDateColumn()
  created!: Date;

  @UpdateDateColumn()
  updated!: Date;
}

Create the DTO​

The DTO (Data Transfer Object) is used by the resolver to represent incoming requests and outgoing responses.

The DTO is where you can:

  • Define fields that should be rendered by graphql.
  • Define fields that should be filterable using the @FilterableField decorator.
  • Define validation that will be used by mutations.

In this example the DTO and entity are two different classes to clearly demonstrate what is required for graphql vs the persistence layer. However, you can combine the two into a single class.

From the root of your project run:

npx nest g cl todo-item.dto todo-item --flat

Now lets fill out the DTO. Add the following to src/todo-item/todo-item.dto.ts.

todo-item/todo-item.dto.ts
import { FilterableField, IDField } from '@ptc-org/nestjs-query-graphql';
import { ObjectType, GraphQLISODateTime, Field, ID } from '@nestjs/graphql';

@ObjectType('TodoItem')
export class TodoItemDTO {
  @IDField(() => ID)
  id!: number;

  @FilterableField()
  title!: string;

  @FilterableField()
  completed!: boolean;

  @Field(() => GraphQLISODateTime)
  created!: Date;

  @Field(() => GraphQLISODateTime)
  updated!: Date;
}


Notice the use of @FilterableField this will let @ptc-org/nestjs-query-graphql know to allow filtering on the corresponding field. If you just use @Field then you will not be able to filter on the corresponding field.

Create the create DTO class.​

From the previously created DTO, @ptc-org/nestjs-query-graphql will automatically create a CreateTodoItem graphql type:

input CreateTodoItem {
  id: ID!
  title: String!
  completed: Boolean!
  created: DateTime!
  updated: DateTime!
}

But in our case, the fields id, created and updated are actually not required when creating a TodoItem: they will be autogenerated. We only need to provide title and completed. To create a DTO that does not require these fields, we can create a custom create DTO:

npx nest g cl todo-item.create.dto todo-item --flat
todo-item/todo-item.create.dto.ts
import { IsBoolean, IsString } from 'class-validator';

@InputType('CreateTodoItem')
export class TodoItemCreateDTO {
  @IsString()
  @Field()
  title!: string;

  @IsBoolean()
  @Field()
  completed!: boolean;
}

Wire everything up.​

Update the todo-item.module to set up the NestjsQueryGraphQLModule and the entities to provide a QueryService.

The NestjsQueryGraphQLModule will automatically create a Resolver that will expose the following queries and mutations:

Queries

  • todoItems - find multiple TodoItems.
  • todoItem - find one TodoItem.

Mutations

  • createManyTodoItems - create multiple TodoItems.
  • createOneTodoItems - create one TodoItem.
  • updateManyTodoItems - update multiple TodoItems.
  • updateOneTodoItems - update one TodoItem.
  • deleteManyTodoItems - delete multiple TodoItemss.
  • deleteOneTodoItems - delete one TodoItem.
import { NestjsQueryGraphQLModule } from '@ptc-org/nestjs-query-graphql';
import { NestjsQueryTypeOrmModule } from '@ptc-org/nestjs-query-typeorm';
import { Module } from '@nestjs/common';
import { TodoItemCreateDTO } from './todo-item.create.dto';
import { TodoItemDTO } from './todo-item.dto';
import { TodoItemEntity } from './todo-item.entity';

@Module({
  imports: [
    NestjsQueryGraphQLModule.forFeature({
      // import the NestjsQueryTypeOrmModule to register the entity with typeorm
      // and provide a QueryService
      imports: [NestjsQueryTypeOrmModule.forFeature([TodoItemEntity])],
      // describe the resolvers you want to expose
      resolvers: [
        {
          EntityClass: TodoItemEntity,
          DTOClass: TodoItemDTO,
          CreateDTOClass: TodoItemCreateDTO,
        },
      ],
    }),
  ],
})
export class TodoItemModule {}

Next update app.module to set up your db connection and the graphql nest modules.

import { ApolloDriver, ApolloDriverConfig } from '@nestjs/apollo';
import { Module } from '@nestjs/common';
import { GraphQLModule } from '@nestjs/graphql';
import { TypeOrmModule } from '@nestjs/typeorm';
import { AppController } from './app.controller';
import { AppService } from './app.service';
import { TodoItemModule } from './todo-item/todo-item.module';

@Module({
  imports: [
    TypeOrmModule.forRoot({
      type: 'postgres',
      database: 'gettingstarted',
      username: 'gettingstarted',
      autoLoadEntities: true,
      synchronize: true,
      logging: true,
    }),
    GraphQLModule.forRoot<ApolloDriverConfig>({
      driver: ApolloDriver,
      // set to true to automatically generate schema
      autoSchemaFile: true,
    }),
    TodoItemModule,
  ],
  controllers: [AppController],
  providers: [AppService],
})
export class AppModule {}

Create a docker-compose.yml file in the root of the project

version: "3"

services:
  postgres:
    image: "postgres:11.5"
    environment:
      - "POSTGRES_USER=gettingstarted"
      - "POSTGRES_DB=gettingstarted"
    expose:
      - "5432"
    ports:
      - "5432:5432"
  # only needed if using mongoose
  mongo:
    image: "mongo:4.4"
    restart: always
    ports:
      - "27017:27017"
  mongo-express:
    image: "mongo-express:latest"
    restart: always
    ports:
      - 8081:8081


Running the Example​

Start the backing services

docker compose up -d

Start the app

npm start

Visit http://localhost:3000/graphql where you should see the playground

Example playground

Exploring The GraphQL Endpoint​

Create a TodoItem​

mutation {
  createOneTodoItem(
    input: { todoItem: { title: "Create One Todo Item", completed: false } }
  ) {
    id
    title
    completed
    created
    updated
  }
}

Create Multiple TodoItems​

mutation {
  createManyTodoItems(
    input: {
      todoItems: [
        { title: "Create Many Todo Items - 1", completed: false }
        { title: "Create Many Todo Items - 2", completed: true }
      ]
    }
  ) {
    id
    title
    completed
    created
    updated
  }
}

Query For Multiple TodoItems​

Query for all todo items​

{
  todoItems {
    pageInfo {
      hasNextPage
      hasPreviousPage
      startCursor
      endCursor
    }
    edges {
      node {
        id
        title
        completed
        created
        updated
      }
      cursor
    }
  }
}

Query for completed todo items​

{
  todoItems(filter: { completed: { is: true } }) {
    pageInfo {
      hasNextPage
      hasPreviousPage
      startCursor
      endCursor
    }
    edges {
      node {
        id
        title
        completed
        created
        updated
      }
      cursor
    }
  }
}

Query For One TodoItem​

Query by id​

{
  todoItem(id: 1) {
    id
    title
    completed
    created
    updated
  }
}

Update a TodoItem​

Lets update the completed TodoItem we created earlier to not be completed.

mutation {
  updateOneTodoItem(input: { id: 3, update: { completed: false } }) {
    id
    title
    completed
    created
    updated
  }
}

Update Multiple TodoItems​

Lets update the completed TodoItem we created earlier to not be completed.

mutation {
  updateManyTodoItems(
    input: { filter: { id: { in: [1, 2] } }, update: { completed: true } }
  ) {
    updatedCount
  }
}

You can check this by running the completed query from above.

Delete One TodoItem​

Lets update delete the first TodoItem.

mutation {
  deleteOneTodoItem(input: { id: 1 }) {
    id
    title
    completed
    created
    updated
  }
}

Delete Many TodoItems​

Lets update delete the create many todo items TodoItem using a filter.

mutation {
  deleteManyTodoItems(
    input: { filter: { title: { like: "Create Many Todo Items%" } } }
  ) {
    deletedCount
  }
}