Creating a RESTful API in NestJS involves several steps. Here’s a step-by-step theoretical guide:
Step 1: Setup a New NestJS Project
- Install Nest CLI:
npm install -g @nestjs/cli
- Create a New Project:
nest new project-name
- Navigate to the Project Directory:
cd project-name
Step 2: Generate a Module, Controller, and Service
- Generate a Module:
nest g module user
- Generate a Controller:
nest g controller user
- Generate a Service:
nest g service user
Step 3: Define the User Entity
-
Create a User Entity:
Create the
src/user/user.entity.ts
file:
export class User {
id: number;
name: string;
email: string;
}
Step 4: Implement the User Service
-
Implement Service Logic:
Open
src/user/user.service.ts
and implement the service methods:
import { Injectable } from '@nestjs/common';
import { User } from './user.entity';
@Injectable()
export class UserService {
private users: User[] = [];
private idCounter = 1;
findAll(): User[] {
return this.users;
}
findOne(id: number): User {
return this.users.find(user => user.id === id);
}
create(user: User): User {
user.id = this.idCounter++;
this.users.push(user);
return user;
}
update(id: number, updatedUser: Partial<User>): User {
const user = this.findOne(id);
if (user) {
Object.assign(user, updatedUser);
}
return user;
}
delete(id: number): void {
this.users = this.users.filter(user => user.id !== id);
}
}
Step 5: Implement the User Controller
-
Implement Controller Logic:
Open
src/user/user.controller.ts
and define the routes:
import { Controller, Get, Post, Put, Delete, Param, Body } from '@nestjs/common';
import { UserService } from './user.service';
import { User } from './user.entity';
@Controller('users')
export class UserController {
constructor(private readonly userService: UserService) {}
@Get()
findAll(): User[] {
return this.userService.findAll();
}
@Get(':id')
findOne(@Param('id') id: string): User {
return this.userService.findOne(+id);
}
@Post()
create(@Body() user: User): User {
return this.userService.create(user);
}
@Put(':id')
update(@Param('id') id: string, @Body() updatedUser: Partial<User>): User {
return this.userService.update(+id, updatedUser);
}
@Delete(':id')
delete(@Param('id') id: string): void {
this.userService.delete(+id);
}
}
Step 6: Update the User Module
-
Update the User Module:
Open
src/user/user.module.ts
and update it to include the controller and service:
import { Module } from '@nestjs/common';
import { UserController } from './user.controller';
import { UserService } from './user.service';
@Module({
controllers: [UserController],
providers: [UserService],
})
export class UserModule {}
Step 7: Integrate the User Module into the App Module
-
Update the App Module:
Open
src/app.module.ts
and update it to include the User module:
import { Module } from '@nestjs/common';
import { UserModule } from './user/user.module';
@Module({
imports: [UserModule],
})
export class AppModule {}
Step 8: Run the Application
- Start the NestJS Application:
npm run start:dev
Step 9: Test the RESTful API
-
Test the API Endpoints:
Use a tool like Postman or curl to test the RESTful API endpoints:
-
GET /users
: Retrieve all users. -
GET /users/:id
: Retrieve a user by ID. -
POST /users
: Create a new user. -
PUT /users/:id
: Update a user by ID. -
DELETE /users/:id
: Delete a user by ID.
-
This guide provides a foundational approach to creating a RESTful API in NestJS. You can further expand and customize it based on your application's requirements.
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