Add community plugin: Elysia HTTP Exception

[codev911]

🚨 Add Elysia HTTP Exception Plugin

Summary

This PR introduces a comprehensive HTTP exception handling plugin for Elysia, inspired by NestJS's HTTP Exception system. The plugin provides structured exception classes for all standard 4xx and 5xx HTTP status codes with type-safe error handling.

Motivation

While building applications with Elysia, I found myself repeatedly creating custom error handling patterns for different HTTP status codes. This led to inconsistent error responses and boilerplate code across projects.

Drawing inspiration from NestJS's elegant HTTP Exception system, I created this plugin to bring the same level of structure and consistency to Elysia applications.

What This Plugin Provides

✨ Features

• Complete HTTP Status Coverage: Support for all standard 4xx and 5xx HTTP status codes
• Type-Safe: Full TypeScript support with proper type definitions
• Flexible Error Data: Accept string messages, objects, or Error instances
• Two Usage Patterns: Use either throw statements or the httpException decorator
• Automatic Error Handling: Built-in handler for common Elysia errors (PARSE, VALIDATION, NOT_FOUND, etc.)
• Zero Configuration: Works out of the box with sensible defaults

🎯 Available Exception Classes

4xx Client Errors:

• BadRequestException (400)
• UnauthorizedException (401)
• ForbiddenException (403)
• NotFoundException (404)
• MethodNotAllowedException (405)
• ConflictException (409)
• UnprocessableEntityException (422)
• TooManyRequestsException (429)
• And 20+ more...

5xx Server Errors:

• InternalServerErrorException (500)
• NotImplementedException (501)
• BadGatewayException (502)
• ServiceUnavailableException (503)
• GatewayTimeoutException (504)
• And more...

Basic Usage Example

import { Elysia } from 'elysia';
import { httpExceptionPlugin, NotFoundException, BadRequestException } from 'elysia-http-exception';

const app = new Elysia()
  .use(httpExceptionPlugin())
  .get('/users/:id', ({ params }) => {
    const userId = parseInt(params.id);
    
    if (isNaN(userId)) {
      throw new BadRequestException('User ID must be a valid number');
    }
    
    if (userId === 404) {
      throw new NotFoundException(`User with ID ${userId} not found`);
    }
    
    return { id: userId, name: `User ${userId}` };
  })
  .listen(3000);

Response Examples

Simple string message:

curl http://localhost:3000/users/invalid

{
  "statusCode": 400,
  "message": "User ID must be a valid number"
}

Custom object data:

throw new UnprocessableEntityException({
  error: 'VALIDATION_FAILED',
  details: {
    field: 'email',
    message: 'Invalid email format'
  },
  timestamp: new Date().toISOString()
});

{
  "error": "VALIDATION_FAILED",
  "details": {
    "field": "email", 
    "message": "Invalid email format"
  },
  "timestamp": "2024-01-15T10:30:00.000Z"
}

Alternative Usage: Decorator Pattern

app.get('/users/:id', ({ params, httpException }) => {
  const userId = parseInt(params.id);
  
  if (isNaN(userId)) {
    return httpException(new BadRequestException('User ID must be a valid number'));
  }
  
  if (userId === 404) {
    return httpException(new NotFoundException(`User with ID ${userId} not found`));
  }
  
  return { id: userId, name: `User ${userId}` };
});

Advanced Examples

Authentication & Authorization

app.get('/profile', ({ headers }) => {
  const authHeader = headers['authorization'];
  
  if (!authHeader) {
    throw new UnauthorizedException({
      error: 'MISSING_AUTH_HEADER',
      message: 'Authorization header is required',
      requiredFormat: 'Bearer <token>'
    });
  }
  
  if (!authHeader.startsWith('Bearer ')) {
    throw new UnauthorizedException('Invalid authorization format');
  }
  
  return { user: { id: 1, name: 'John Doe' } };
});

Rate Limiting

app.get('/api/data', () => {
  const rateLimitExceeded = checkRateLimit(); // Your logic
  
  if (rateLimitExceeded) {
    throw new TooManyRequestsException({
      message: 'Rate limit exceeded',
      retryAfter: 60,
      limit: 100,
      remaining: 0
    });
  }
  
  return { data: 'Your API data' };
});

File Upload Validation

app.post('/upload', ({ request }) => {
  const contentLength = parseInt(request.headers.get('content-length') || '0');
  const maxSize = 5 * 1024 * 1024; // 5MB
  
  if (contentLength > maxSize) {
    throw new PayloadTooLargeException({
      error: 'FILE_TOO_LARGE',
      message: 'File size exceeds maximum allowed size',
      maxSize: `${maxSize / 1024 / 1024}MB`,
      receivedSize: `${(contentLength / 1024 / 1024).toFixed(2)}MB`
    });
  }
  
  return { message: 'Upload successful' };
});

Built-in Error Handling

The plugin automatically handles common Elysia errors:

• PARSE: JSON parsing errors → 400 Bad Request
• VALIDATION: Schema validation errors → 400 Bad Request
• NOT_FOUND: Route not found → 404 Not Found
• INVALID_COOKIE_SIGNATURE: Invalid cookies → 400 Bad Request
• INVALID_FILE_TYPE: Unsupported file types → 415 Unsupported Media Type

Inspiration from NestJS

This plugin draws heavy inspiration from NestJS's HTTP Exception system, specifically:

• Exception Class Structure: Similar to NestJS HttpException classes
• Built-in Exception Types: Following NestJS's comprehensive HTTP exception catalog
• Flexible Message Handling: Supporting the same message formats as NestJS exceptions

NestJS References:

• Exception Filters Documentation
• Built-in HTTP Exceptions
• Throwing Standard Exceptions

Package Information

• Package Name: elysia-http-exception
• Repository: https://github.com/codev911/elysia-http-exception
• npm: https://www.npmjs.com/package/elysia-http-exception
• License: MIT
• TypeScript: Full type definitions included

Installation

# Using bun (recommended)
bun add elysia-http-exception

# Using npm
npm install elysia-http-exception

Testing & Quality

• ✅ Comprehensive test coverage (198 unit tests)
• ✅ E2E tests with example applications
• ✅ TypeScript strict mode compliance
• ✅ Full documentation with examples
• ✅ Automated CI/CD pipeline

Why This Should Be Added

1. Consistency: Provides a standardized way to handle HTTP exceptions across Elysia applications
2. Developer Experience: Reduces boilerplate and improves error handling patterns
3. Type Safety: Full TypeScript support with intellisense
4. Community Value: Fills a common need in the Elysia ecosystem
5. Proven Pattern: Based on successful patterns from established frameworks like NestJS
6. Zero Breaking Changes: Completely additive, doesn't affect existing code

Community Impact

This plugin addresses a common pattern that many Elysia developers implement manually. By providing a standardized, well-tested solution, it can:

• Reduce development time for new projects
• Improve consistency across the Elysia ecosystem
• Lower the learning curve for developers coming from other frameworks
• Serve as a reference implementation for plugin development

---

I believe this plugin would be a valuable addition to the official Elysia plugin ecosystem. It's production-ready, well-documented, and solves a real problem that many developers face when building APIs with Elysia.

Thank you for considering this contribution to the Elysia community! 🚀

Summary by CodeRabbit

• Documentation
  • Added a new Community plugin entry: “Elysia HTTP Exception,” including a link and brief description to aid discovery and adoption.
  • Improves the completeness and visibility of error-handling plugins within the catalog for users evaluating options.
  • No changes to page structure, functionality, or existing content.
  • No API or behavior changes; no user action required.

[coderabbitai]

Walkthrough

Adds a new community plugin entry, “Elysia HTTP Exception,” with a link and description to docs/plugins/overview.md. No other changes.

Changes

Cohort / File(s)	Summary
Docs — Plugins overview docs/plugins/overview.md	Added a new Community plugins entry: “Elysia HTTP Exception” with link and description; no structural changes.

Estimated code review effort

🎯 1 (Trivial) | ⏱️ ~2 minutes

Poem

I twitch my whiskers, tap my paw,
A plugin hops into the docs—ooh, la!
Elysia’s errors, neatly penned,
A gentle link, a tidy friend.
Thump of approval—onward, awe! 🐇✨

---

📜 Recent review details

Configuration used: CodeRabbit UI
Review profile: CHILL
Plan: Pro

📥 Commits

Reviewing files that changed from the base of the PR and between 2b219a3 and 02f4b4e.

📒 Files selected for processing (1)

• docs/plugins/overview.md (1 hunks)

🔇 Additional comments (2)

docs/plugins/overview.md (2)

56-56: LGTM: solid addition to Community plugins.

Entry looks consistent in naming and link style with surrounding items.

---

56-56: Refine plugin description to highlight TypeScript-first design, decorator support, and automatic handling

Verified that the GitHub repo (200 OK) and npm package (v0.1.3) exist, and README confirms full TypeScript support, decorator usage, and automatic error handling. Apply this change:

• docs/plugins/overview.md (line 56)

-   [Elysia HTTP Exception](https://github.com/codev911/elysia-http-exception) - Elysia plugin for HTTP 4xx/5xx error handling with structured exception classes
+   [Elysia HTTP Exception](https://github.com/codev911/elysia-http-exception) - TypeScript-first HTTP exception system with structured 4xx/5xx exception classes, decorator support, and automatic handling of common Elysia errors

✨ Finishing Touches

🧪 Generate unit tests

• Create PR with unit tests
• Post copyable unit tests in a comment

---

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