How to create Nest JS API response format common for each API?

Question

I am new to nestjs and was stuck with making a common response body for all the APIs. Currently, I am making use of the map for getting the response from the collection but not have an idea how to format the response in the below-mentioned way.

I am currently getting response body like below -

Response body        
        
[         
  {            
    "userId": "602a0f175bbd45688cd001f4",        
    "firstName": "Gagan",  
    "lastName": "Pandya",  
    "email": "gagankumar.pandya@galaxyweblinks.in",  
    "status": "active"  
  },  
  {
    "userId": "603f3b547508bbd77a3d6fb5",    
    "firstName": "Kunal",    
    "lastName": "Ghosh",    
    "email": "kunal.ghosh@galaxyweblinks.in",    
    "status": "active"    
  }    
]
  

Need to set it as-

{
    "statusCode": 200,   
    "message": "User Listing",   
    "data":[    
  {   
    "userId": "602a0f175bbd45688cd001f4",    
    "firstName": "Gagan",   
    "lastName": "Pandya",   
    "email": "gagankumar.pandya@galaxyweblinks.in",   
    "status": "active"    
  },    
  {    
    "userId": "603f3b547508bbd77a3d6fb5",    
    "firstName": "Kunal",    
    "lastName": "Ghosh",     
    "email": "kunal.ghosh@galaxyweblinks.in",      
    "status": "active"    
  }     
]    
}    

Below is my controller code -

  @Get('/users-listing')    
  // @UseGuards(AuthGuard('jwt'))    
 // @Roles('Super Admin')    
  @ApiOperation({ title: 'Lists of users' })    
  @ApiOkResponse({})    
  @HttpCode(HttpStatus.OK)    
  async getAllUsers() {    
    return this.usersService.findAllUsers();    
  }    
           

And please find service.ts file code -

   async findAllUsers(): Promise<User[]> {     
    const users = await this.userModel.find().exec();   
    const usersArr = [];    
    await Promise.all(    
      users.map(async users => {    
        usersArr.push({ userId: users._id, firstName: users.firstName, lastName: users.lastName, email: users.email, status: users.status });    
      }),    
    );    
    return usersArr;    
  }    

    Thanks in advance!   

Answer 1

Create a given transform interceptor

import {
  Injectable,
  NestInterceptor,
  ExecutionContext,
  CallHandler,
} from '@nestjs/common';
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';

export interface Response<T> {
  statusCode: number;
  message: string;
  data: T;
}

@Injectable()
export class TransformInterceptor<T>
  implements NestInterceptor<T, Response<T>>
{
  intercept(
    context: ExecutionContext,
    next: CallHandler
  ): Observable<Response<T>> {
    return next.handle().pipe(
      map((data) => ({
        statusCode: context.switchToHttp().getResponse().statusCode,
        reqId: context.switchToHttp().getRequest().reqId,
        message: data.message || '',
        data: data,
      }))
    );
  }
}

Add the upper interceptor to the controller

@UseInterceptors(TransformInterceptor)

export class DocumentController {}

Finally, return the response from the controller.

Every response will pass through this interceptor and create a static response format.

You can modify the interceptor according to your requirement.

Answer 2

I hope the following would help you

import {
    Body,
    Controller,
    Get,
    Param,
    Res,
    HttpStatus,
} from '@nestjs/common';
    
@Get('/users-listing')
// @UseGuards(AuthGuard('jwt'))
// @Roles('Super Admin')
@ApiOperation({ title: 'Lists of users' })
@ApiOkResponse({})
async getAllUsers(@Res() res) {
    const users = this.usersService.findAllUsers();
    return res.status(HttpStatus.OK).json({
        status: 'success',
        data: {
            users,
        }
    });
}