Creating a Complete CRUD API Part Two

In this part, you will complete the CRUD API by adding routes for updating and deleting users.

First, update the service:

import { Injectable, NotFoundException } from '@nestjs/common';

@Injectable()
export class UsersService {
  private users = [
    { id: 1, name: 'Alice', age: 30 },
    { id: 2, name: 'Bob', age: 25 },
  ];

  getAllUsers() {
    return this.users;
  }

  createUser(user: { name: string; age: number }) {
    const newUser = {
      id: this.users.length + 1,
      ...user,
    };

    this.users.push(newUser);
    return newUser;
  }

  updateUser(id: number, updatedUser: { name: string; age: number }) {
    const user = this.users.find(user => user.id === id);

    if (!user) {
      throw new NotFoundException('User not found');
    }

    user.name = updatedUser.name;
    user.age = updatedUser.age;

    return user;
  }

  deleteUser(id: number) {
    const userIndex = this.users.findIndex(user => user.id === id);

    if (userIndex === -1) {
      throw new NotFoundException('User not found');
    }

    const deletedUser = this.users[userIndex];
    this.users.splice(userIndex, 1);

    return deletedUser;
  }
}

Here is what is happening:

• updateUser(): finds a user by ID and updates the data;
• deleteUser(): finds a user by ID and removes it from the array;
• NotFoundException: returns an error if the user does not exist.

Now update the controller:

import { Controller, Get, Post, Put, Delete, Param, Body } from '@nestjs/common';
import { UsersService } from './users.service';

@Controller('users')
export class UsersController {
  constructor(private usersService: UsersService) {}

  @Get()
  getUsers() {
    return this.usersService.getAllUsers();
  }

  @Post()
  createUser(@Body() body: { name: string; age: number }) {
    return this.usersService.createUser(body);
  }

  @Put(':id')
  updateUser(
    @Param('id') id: string,
    @Body() body: { name: string; age: number }
  ) {
    return this.usersService.updateUser(Number(id), body);
  }

  @Delete(':id')
  deleteUser(@Param('id') id: string) {
    return this.usersService.deleteUser(Number(id));
  }
}

Here is what is happening:

• @Put(':id'): updates a user with a specific ID;
• @Delete(':id'): deletes a user with a specific ID;
• @Param('id'): gets the ID from the URL;
• Number(id): converts the route parameter from string to number.

At this point, your API can create, read, update, and delete users.