NestJs - Build CRUD To-do App and MongDb

Let’s build a NestJS To-Do App with MongoDB step-by-step. This will include CRUD operations (Create, Read, Update, Delete) and cover essential NestJS concepts like modules, controllers, services, and MongoDB integration. I'll assume you're using the MongoDB Cloud Service for your database.

My Project on GitHub: https://github.com/Taki089Linux/nestj-todo-app/

I use NodeJS v20.17.0 for this.

1. Prerequisites

• Node.js installed (v16+ recommended).
• MongoDB Cloud or Local MongoDB running.
• Nest CLI installed:

  npm install -g @nestjs/cli

---

2. Create the NestJS Project

Run the following command to create a new project:

nest new nest-todo-app

• Choose NPM or Yarn as the package manager.

---

3. Install Dependencies

We need to install the MongoDB driver and @nestjs/mongoose for MongoDB integration:

npm install @nestjs/mongoose mongoose

---

4. Set Up a ToDo Module

Generate a ToDo module using the CLI:

nest g module todo

Generate a controller and service for the ToDo module:

nest g controller todo
nest g service todo

---

5. Create the ToDo Schema

Define the schema to interact with the MongoDB collection. Create a file called todo.schema.ts inside the todo folder:

import { Prop, Schema, SchemaFactory } from '@nestjs/mongoose';
import { Document } from 'mongoose';

@Schema()
export class ToDo extends Document {
  @Prop({ required: true })
  title: string;

  @Prop()
  description: string;

  @Prop({ default: false })
  isCompleted: boolean;

  @Prop({ default: Date.now })
  createdAt: Date;
}

export const ToDoSchema = SchemaFactory.createForClass(ToDo);

---

6. Register the ToDo Schema in the Module

In todo.module.ts, import and register the schema with Mongoose:

import { Module } from '@nestjs/common';
import { MongooseModule } from '@nestjs/mongoose';
import { ToDo, ToDoSchema } from './todo.schema';
import { ToDoService } from './todo.service';
import { ToDoController } from './todo.controller';

@Module({
  imports: [
    MongooseModule.forFeature([{ name: ToDo.name, schema: ToDoSchema }]),
  ],
  controllers: [ToDoController],
  providers: [ToDoService],
})
export class ToDoModule {}

---

7. Connect MongoDB to the Application

In app.module.ts, import MongooseModule and connect to your MongoDB instance:

import { Module } from '@nestjs/common';
import { MongooseModule } from '@nestjs/mongoose';
import { ToDoModule } from './todo/todo.module';

@Module({
  imports: [
    MongooseModule.forRoot('mongodb+srv://<username>:<password>@cluster.mongodb.net/todo-app?retryWrites=true&w=majority'),
    ToDoModule,
  ],
})
export class AppModule {}

Replace <username> and <password> with your MongoDB credentials.

---

8. Create ToDo Service

In todo.service.ts, implement the CRUD logic:

import { Injectable, NotFoundException } from '@nestjs/common';
import { InjectModel } from '@nestjs/mongoose';
import { Model } from 'mongoose';
import { ToDo } from './todo.schema';

@Injectable()
export class ToDoService {
  constructor(@InjectModel(ToDo.name) private readonly todoModel: Model<ToDo>) {}

  async findAll(): Promise<ToDo[]> {
    return this.todoModel.find().exec();
  }

  async findOne(id: string): Promise<ToDo> {
    const todo = await this.todoModel.findById(id).exec();
    if (!todo) {
      throw new NotFoundException('ToDo not found');
    }
    return todo;
  }

  async create(data: Partial<ToDo>): Promise<ToDo> {
    const newToDo = new this.todoModel(data);
    return newToDo.save();
  }

  async update(id: string, data: Partial<ToDo>): Promise<ToDo> {
    const updatedToDo = await this.todoModel
      .findByIdAndUpdate(id, data, { new: true })
      .exec();
    if (!updatedToDo) {
      throw new NotFoundException('ToDo not found');
    }
    return updatedToDo;
  }

  async delete(id: string): Promise<void> {
    const result = await this.todoModel.findByIdAndDelete(id).exec();
    if (!result) {
      throw new NotFoundException('ToDo not found');
    }
  }
}

---

9. Create ToDo Controller

In todo.controller.ts, define routes for CRUD operations:

import { Controller, Get, Post, Put, Delete, Body, Param } from '@nestjs/common';
import { ToDoService } from './todo.service';
import { ToDo } from './todo.schema';

@Controller('todos')
export class ToDoController {
  constructor(private readonly todoService: ToDoService) {}

  @Get()
  async findAll(): Promise<ToDo[]> {
    return this.todoService.findAll();
  }

  @Get(':id')
  async findOne(@Param('id') id: string): Promise<ToDo> {
    return this.todoService.findOne(id);
  }

  @Post()
  async create(@Body() data: Partial<ToDo>): Promise<ToDo> {
    return this.todoService.create(data);
  }

  @Put(':id')
  async update(@Param('id') id: string, @Body() data: Partial<ToDo>): Promise<ToDo> {
    return this.todoService.update(id, data);
  }

  @Delete(':id')
  async delete(@Param('id') id: string): Promise<void> {
    return this.todoService.delete(id);
  }
}

---

10. Run and Test

1. Start the server:

   npm run start:dev

1. Use a tool like Postman or cURL to test the endpoints:

   • GET /todos: Fetch all ToDo items.
   • GET /todos/:id: Fetch a single ToDo by ID.
   • POST /todos: Create a new ToDo.

    {
      "title": "Learn NestJS",
      "description": "Build a ToDo app",
      "isCompleted": false
    }
   

• PUT /todos/:id: Update a ToDo by ID.
• DELETE /todos/:id: Delete a ToDo by ID.

---

11. Folder Structure

Your project should look like this:

src/
├── todo/
│   ├── todo.controller.ts
│   ├── todo.service.ts
│   ├── todo.module.ts
│   ├── todo.schema.ts
├── app.module.ts
├── main.ts

---

12. Enhance the App

Here are some ways to improve:

1. Validation: Add class-validator for input validation.
2. Pagination: Implement pagination for findAll.
3. Swagger: Use @nestjs/swagger to generate API docs.
4. Authentication: Add authentication using Passport.js with JWT.

Comments

[Ciphernutz]

Very informative post! 🚀 NestJS, combined with MongoDB, is a powerful stack for building scalable and efficient applications.