Welcome to LeviFREE's Blog

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mkdir my-api && cd my-api
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npm init -y
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npm install express cors helmet morgan
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npm install -D typescript @types/express @types/node tsx

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src/
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├── routes/
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│   ├── users.ts
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│   └── posts.ts
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├── middleware/
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│   ├── auth.ts
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│   └── errorHandler.ts
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├── controllers/
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│   └── userController.ts
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├── types/
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│   └── index.ts
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└── app.ts

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import express from 'express';
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import cors from 'cors';
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import helmet from 'helmet';
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import morgan from 'morgan';
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import { userRouter } from './routes/users';
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import { errorHandler } from './middleware/errorHandler';
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const app = express();
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// Middleware
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app.use(helmet());
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app.use(cors());
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app.use(morgan('dev'));
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app.use(express.json());
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// Routes
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app.use('/api/users', userRouter);
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// Error handling (must be last)
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app.use(errorHandler);
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app.listen(3000, () => {
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  console.log('Server running on port 3000');
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});

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import { Router } from 'express';
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export const userRouter = Router();
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userRouter.get('/',       getUsers);     // List all
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userRouter.get('/:id',    getUser);      // Get one
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userRouter.post('/',      createUser);   // Create
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userRouter.put('/:id',    updateUser);   // Replace
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userRouter.patch('/:id',  patchUser);    // Partial update
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userRouter.delete('/:id', deleteUser);   // Delete

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import { Request, Response, NextFunction } from 'express';
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class AppError extends Error {
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  constructor(public statusCode: number, message: string) {
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    super(message);
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  }
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}
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export const errorHandler = (
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  err: Error,
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  req: Request,
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  res: Response,
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  next: NextFunction
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) => {
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  if (err instanceof AppError) {
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    return res.status(err.statusCode).json({
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      error: err.message,
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    });
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  }
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  console.error(err);
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  res.status(500).json({ error: 'Internal Server Error' });
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};