gaganssingh / coffeelicious-nestjs-project

Starting a new NestJS app:

• Install the nestjs cli npm i -g @nestjs/cli
• Generate a new project using nestjs cli nest new <PROJECT_NAME>

Validation pipe (request body)

• Validation flow

  1. A route receives a request with a body.
  2. The validation pipe uses class-transformer to turn body (plain object/json) into an instance of the DTO class.
  3. The validation pipe uses class-validator to validate the request body.
  4. If no errors during validation, request forwarded to request handler.
  4. Is errors during validation, error response sent back to the client.
  

• Implementing request body validation:

  1. Install supporting libs: npm i class-validator class-transformer

  2. Configure global validation main.ts:

     import { ValidationPipe } from "@nestjs/common";
     .
     .
     .
     async function bootstrap() {
       const app = await NestFactory.create(MessagesModule);
     
       // Add validation pipe here
       app.useGlobalPipes(new ValidationPipe());
     
       await app.listen(3000);
     }
     

  3. Create class (DTO) describing properties on req. body to validate: src/messages/dtos/create-message.dto.ts:

     export class createMessageDto {
       content: string;
     }
     
     

  4. Add validation rules: src/messages/dtos/create-message.dto.ts:

     import { IsString } from "class-validator";
     
     export class createMessageDto {
       @IsString()
       content: string;
     }
     
     

  5. Apply validation class to request handler: src/messages/messages.controller.ts:

     @Controller("messages")
     export class MessagesController {
       .
       .
       .
     
       @Post()
       createMessage(@Body() body: createMessageDto) {
         console.log(body);
       }
     
       .
       .
       .
     }
     

Using NestJS CLI:

• Module generation: nest generate module <NAME> E.g. nest generate module cpu Responds with CREATE src/cpu/cpu.module.ts
• Service Generation: nest generate service <NAME> E.g.: nest generate service cpu Responds with:

  CREATE src/cpu/cpu.service.spec.ts (439 bytes)
  CREATE src/cpu/cpu.service.ts (87 bytes)
  UPDATE src/cpu/cpu.module.ts (151 bytes)
  

• Controller generation: nest generate controller <ASSOCIATED_MODULE>/<CONTROLLER_NAME> --flat E.g. nest generate controller cpu/cpu --flat Responds with

  CREATE src/cpu/cpu.controller.spec.ts
  CREATE src/cpu/cpu.controller.ts
  UPDATE src/cpu/cpu.module.ts
  

• Generate a DTO class: nest generate class coffees/dto/create-coffee.dto --no-spec Responds with:

  CREATE src/coffees/dto/create-coffee.dto.ts
  

  Generates:

  export class CreateCoffeeDto {
  
  }