[Nestjs] 手摸手之简单封装API接口的返回结果

import { Injectable, NestInterceptor, ExecutionContext, CallHandler } from '@nestjs/common';
import { Observable } from 'rxjs';
import { map } from 'rxjs/operators';
// 统一成功响应的数据结构
export interface SuccessResponse<T> {
  code: number;
  message: string;
  data: T;
}
// 统一错误响应的数据结构
export interface ErrorResponse {
  code: number;
  message: string;
}
// 统一分页响应的数据结构
export interface PaginatedResponse<T> {
  code: number;
  message: string;
  data: T[];
  total: number;
}
@Injectable()
export class TransformInterceptor<T> implements NestInterceptor<T, SuccessResponse<T>> {
  intercept(context: ExecutionContext, next: CallHandler): Observable<SuccessResponse<T>> {
    return next.handle().pipe(
      map(data => ({
        code: 0, // 自定义成功响应的状态码
        message: '请求成功', // 自定义成功响应的消息
        data,
      })),
    );
  }
}
@Injectable()
export class ErrorInterceptor implements NestInterceptor {
  intercept(context: ExecutionContext, next: CallHandler): Observable<any> {
    return next.handle().pipe(
      catchError(error => {
        return throwError({
          code: error.status || 500, // 自定义错误响应的状态码，默认为 500
          message: error.message || '服务器错误', // 自定义错误响应的消息，默认为 '服务器错误'
        });
      }),
    );
  }
}

import { Controller, Get, UseInterceptors } from '@nestjs/common';
import { TransformInterceptor, ErrorInterceptor, SuccessResponse, ErrorResponse, PaginatedResponse } from './common';
@Controller('users')
@UseInterceptors(TransformInterceptor, ErrorInterceptor)
export class UsersController {
  // 成功响应示例
  @Get(':id')
  getUserById(): SuccessResponse<User> {
    const user: User = {
      id: 1,
      name: 'John Doe',
      email: 'johndoe@example.com',
    };
    return user;
  }
  // 错误响应示例
  @Get(':id')
  getUserById(): ErrorResponse {
    throw new NotFoundException('用户未找到');
  }
  // 分页响应示例
  @Get()
  getAllUsers(): PaginatedResponse<User> {
    const users: User[] = [
      {
        id: 1,
        name: 'John Doe',
        email: 'johndoe@example.com',
      },
      {
        id: 2,
        name: 'Jane Smith',
        email: 'janesmith@example.com',
      },
      // ...
    ];
    return {
      data: users,
      total: users.length,
    };
  }
}