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Error Handling

ExpressPro provides a robust error handling system with a custom error class and global error handler.

AppError Class​

The AppError class extends the native Error class and adds HTTP status code support.

import {AppError} from 'expresspro';

// Create a custom error
throw new AppError('Resource not found', 404);

Properties​

  • message (string): Error message
  • statusCode (number): HTTP status code
  • stack (string): Error stack trace

Global Error Handler​

ExpressPro includes a global error handler middleware that catches and processes all errors.

import express from 'expresspro';

const app = express();

// Add error handler middleware
app.use(express.error);

Error Response Format​

{
  success: false,
  message: string,
  data: {}
}

Usage Examples​

Basic Error Handling​

import express from 'expresspro';

const app = express();

// Route with error
app.get('/users/:id', express.asyncHandler(async (req, res) => {
  const user = await findUser(req.params.id);
  
  if (!user) {
    throw new express.AppError('User not found', 404);
  }
  
  res.json({ user });
}));

// Add error handler
app.use(express.error);

Custom Error Handler​

  • In case of you don't want to built in error handler. You can define your custom handler. (Not recommended Use if needed)
import express from 'expresspro';

const app = express();

// Custom error handler
app.use((err, req, res, next) => {
  if (err instanceof express.AppError) {
    return res.status(err.statusCode).json({
      success: false,
      message: err.message,
      error: {
        statusCode: err.statusCode,
        message: err.message
      }
    });
  }
  
  // Handle other errors
  return res.status(500).json({
    success: false,
    message: 'Internal server error',
    error: {
      statusCode: 500,
      message: err.message
    }
  });
});

Best Practices​

  1. Always use express.asyncHandler for async route handlers
  2. Throw AppError for known error cases
  3. Use appropriate HTTP status codes
  4. Keep error messages user-friendly
  5. Log errors for debugging
  6. Don't expose sensitive information in error messages

Common HTTP Status Codes​

  • 400: Bad Request
  • 401: Unauthorized
  • 403: Forbidden
  • 404: Not Found
  • 409: Conflict
  • 422: Unprocessable Entity
  • 500: Internal Server Error

Error Handling with Async Handler​

import express from 'expresspro';

const app = express();

app.get('/async-route', express.asyncHandler(async (req, res) => {
  // No need for try-catch
  const data = await someAsyncOperation();
  
  if (!data) {
    throw new express.AppError('Data not found', 404);
  }
  
  res.json({ data });
}));

Next Steps​