Make simple CRUD requests with NestJS

This article details the steps involved in creating a basic CRUD (Create, Read, Update, Delete) API using NestJS, a popular framework for building Node.js applications.

Prerequisites

Node.js and npm (or yarn) installed on your system.

Installation

Install NestJS CLI:
Create a new NestJS project
Start the development server

Project Structure

NestJS utilizes a modular approach, where functionalities are organized into modules. The core building blocks include:

Modules: Group controllers, services, and other providers.
Controllers: Handle incoming requests and interact with services.
Services: Implement business logic and interact with data sources.

CRUD Operations

1. Create

2. Read

3. Update

4. Delete

Additional Features

Data Transfer Objects (DTOs): Define DTOs to handle data validation and transfer between layers.
Filtering and Searching: Implement functionalities to filter and search tasks based on criteria.

Testing with Postman

Download and install Postman, a popular API client.
Use Postman to send requests (GET, POST, PUT, DELETE) to the defined API endpoints with appropriate data.
Verify the responses and ensure they align with expectations.

Download Node.js®

bash

# installs nvm (Node Version Manager)
curl -o-
https://raw.githubusercontent.com/nvm-sh/nvm/v0.39.7/install.sh | bash# download and install Node.js
(you may need to restart the terminal)nvm install 20# verifies the right Node.js version is in the
environmentnode -v # should print `v20.14.0`# verifies the right NPM version is in the
environmentnpm -v # should print `10.7.0`

text

node -v # should print `v20.14.0`v20.14.0

Install Nestjs

bash

yarn global add @nestjs/cli

bash

npm install -g @nestjs/cli

Extension for vscode

Format document

Install new project

text

nest new nestjs-task-management? Which package manager would you ❤️  to use? yarn

Get start

bash

cd nestjs-task-management
yarn run start

Run Server

text

http://127.0.0.1:3000/

Structure of project

decorators

typescript

@Module({
  imports: [], controllers: [AppController], providers: [AppService],
})

What you need to know about Decorators

Decorator Pattern — Design Patterns (ep 3)

Python Decorators in 1 Minute!

Golang decorators pattern

Run in developer mode

bash

yarn start:dev

Nest Command line

text

nest g --help

Create Nest module

text

nest g module tasks_name

Create Nest controller

text

nest g controller tasks_name

Create a Nest Controller without a test

text

nest g controller tasks --no-spec

typescript

import {
  Controller
}
from '@nestjs/common';
@Controller('tasks')
export class TasksController {
}

Create Services

text

nest g service tasks --no-spec

Added to module

typescript

import {
  Module
}
from '@nestjs/common';
import {
  TasksController
}
from './tasks.controller';
import {
  TasksService
}
from './tasks.service';
@Module({
  controllers: [TasksController], providers: [TasksService],
})
export class TasksModule {
}

Add service to controller constructor

typescript

import {
  Controller
}
from '@nestjs/common';
import {
  TasksService
}
from './tasks.service';
@Controller('tasks')
export class TasksController {
  tasksService: TasksService;
  constructor(tasksService: TasksService) {
    this.tasksService = tasksService;
  }
  helloWorld() {
    this.tasksService.helloWorld();
  }
}

Set service as private element in Controller

typescript

import {
  Controller
}
from '@nestjs/common';
import {
  TasksService
}
from './tasks.service';
@Controller('tasks')
export class TasksController {
  constructor(private tasksService: TasksService) {
  }
  helloWorld() {
    this.tasksService.helloWorld();
  }
}

Define Controller and service example

controller

typescript

import {
  Controller, Get
}
from '@nestjs/common';
import {
  TasksService
}
from './tasks.service';
@Controller('tasks')
export class TasksController {
  constructor(private tasksService: TasksService) {
  }
  @Get() getAllTasks() {
    return this.tasksService.getAllTasks();
  }
}

Service

typescript

@Injectable()
export class TasksService {
  private tasks = [];
  getAllTasks() {
    this.tasks.push({
      id: 1, title: 'Task 1', description: 'Description 1'
    });
    return this.tasks;
  }
}

postman

Download Postman

Create model

tasks.model.ts

typescript

export interface Task {
  id: number;
  title: string;
  description: string;
  status: TaskStatus;
}
export enum TaskStatus {
  OPEN = 'OPEN', IN_PROGRESS = 'IN_PROGRESS', DONE = 'DONE',
}

tasks.service.ts

typescript

import {
  Injectable
}
from '@nestjs/common';
import {
  Task
}
from './tasks.model';
@Injectable()
export class TasksService {
  private tasks: Task[] = [];
  getAllTasks(): Task[] {
    return this.tasks;
  }
}

tasks.controller.ts

typescript

import {
  Controller, Get
}
from '@nestjs/common';
import {
  TasksService
}
from './tasks.service';
import {
  Task
}
from './tasks.model';
@Controller('tasks')
export class TasksController {
  constructor(private tasksService: TasksService) {
  }
  @Get() getAllTasks(): Task[] {
    return this.tasksService.getAllTasks();
  }
}

Create task

add uuid

bash

yarn add uuidimport { v4 as uuid } from 'uuid';id: uuid(),

add service

typescript

createTask(title: string, description: string): Task {    const task: Task = {      id: uuid(),
title,      description,      status: TaskStatus.OPEN,    };    this.tasks.push(task);    return
task;  }

add controller

typescript

@Post() createTask(@Body('title') title: string, @Body('description') description: string,): Task {
  console.log(title, description);
  return this.tasksService.createTask(title, description);
}

Data Transfer Object (DTO)

Transfer data to different layers.

http request -> Controller -> Service -> Controller -> http response

It would be necessary to add all of these parts when adding a new element.

DTO

typescript

export class CreateTaskDto {
  title: string;
  description: string;
}

Controller

typescript

@Post() createTask(@Body() createTaskDto: CreateTaskDto): Task {
  console.log(createTaskDto.title, createTaskDto.description);
  return this.tasksService.createTask(createTaskDto);
}

Service

javascript

createTask(createTaskDto: CreateTaskDto): Task {    const { title, description } = createTaskDto;
const task: Task = {      id: uuid(),      title,      description,      status: TaskStatus.OPEN,
};    this.tasks.push(task);    return task;  }

Add get method id

Controller

typescript

@Get('/:id') getTaskById(@Param('id') id: number): Task {
  return this.tasksService.getTaskById(id);
}

Service

typescript

getTaskById(id: number): Task {    return this.tasks.find((task) => task.id === id);  }

Delete Task

controller

typescript

@Delete('/:id') deleteTask(@Param('id') id: number): void {
  return this.tasksService.deleteTask(id);
}

service

typescript

deleteTask(id: number): void {    this.tasks = this.tasks.filter((task) => task.id !== id);  }

Update Task

controller

typescript

@Patch('/:id/status') updateTaskStatus(@Param('id') id: string, @Body('status') status:
Task['status'],): Task {
  return this.tasksService.updateTaskStatus(id, status);
}

service

typescript

updateTaskStatus(id: string, status: TaskStatus): Task {    const task = this.getTaskById(id);
console.log(status);    task.status = status;    return task;  }

Search Task

dto

typescript

import {
  TaskStatus
}
from '../tasks.model';
export class GetTasksFilterDto {
  status?: TaskStatus;
  search?: string;
}

controller

typescript

@Get() getTasks(@Query() filterDTO: GetTasksFilterDto): Task[] {
  if (Object.keys(filterDTO).length) {
    return this.tasksService.getTasksWithFilters(filterDTO);
  }
  else {
    return this.tasksService.getAllTasks();
  }
}

service

javascript

getTasksWithFilters(filterDTO: GetTasksFilterDto): Task[] {    const { status, search } = filterDTO;
let tasks = this.getAllTasks();    if (status) {      tasks = tasks.filter((task) => task.status ===
status);    }    if (search) {      tasks = tasks.filter(        (task) =>
task.title.includes(search) || task.description.includes(search),      );    }    return tasks;  }

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Make simple CRUD requests with NestJS