Nest.js Messages

Nest CLI

# https://docs.nestjs.com/cli/overview

# Install Nest CLI
npm i -g @nestjs/cli

# Create new project
nest new nest-messages
cd nest-messages

# Run project
npm run start:dev

# Generate module
nest g module messages

# Generate controller (flat: no controller folder)
nest g controller messages/messages --flat

Nest Request Decorators

Decorator	Description
@Headers()	Access header information
@Body()	Access the request body
@Param('id')	Accesses request parameters
@Query()	Access request query parameters

Validation Pipe

At app bootstrap: Use a global validation pipe (middleware) to validate incoming request data.

app.useGlobalPipes(new ValidationPipe());

Data Transfer Object (DTO)

Description of how an object looks like that is transported from A to B.

export class CreateMessageDto {
  @IsString()
  content: string;
}

The emitDecoratorMetadata allows DTO type information to survive compilation:

// TS: body type 'CreateMessageDto'
@Post()
createMessage(@Body() body: CreateMessageDto) {
  console.log(body);
}

// JS: after compilation
__metadata('design:parmtypes', [create_message_dto_1.CreateMessageDto]);

📦 class-transformer

Imagine to get a plain JSON object. Class transformer turns a plain object into a instance of a class.

📦 class-validator

Handles validation using decorators.

Dependency Injection (DI)

In the service file (and repository file) you have to add the @Injectable() decorator to the class (or use the @Injectable() decorator factory function

@Injectable()
export class MessagesService {}

In the Module file you have to add the service to the providers array:

@Module({
  controllers: [MessagesController],
  providers: [MessagesService],
})

artiphishle/edu-nestjs-messages