OAuth2 Dependency Injection Fix

Problem

When the OAuth2 authorization flow was initiated, the OAuth2AuthorizationMiddleware was receiving a ContainerInstance object instead of the actual OAuth2Service instance. This caused the following error:

OAuth2AuthorizationMiddleware: oauth2Service is: ContainerInstance {
  services: [...],
  id: 'default'
}
OAuth2AuthorizationMiddleware: oauth2Service type: object
OAuth2AuthorizationMiddleware: isInitialized is not a function
OAuth2AuthorizationMiddleware: Available methods: [ 'services', 'id' ]

Root Cause

The issue was caused by how routing-controllers handles dependency injection when using the @UseBefore() decorator with middleware classes.

When you use @UseBefore(OAuth2AuthorizationMiddleware) on a controller, routing-controllers attempts to instantiate the middleware, but the constructor parameter injection wasn't working correctly with TypeDI despite calling useContainer(Container).

Original Code (Broken)

@Service()
export default class OAuth2AuthorizationMiddleware implements ExpressMiddlewareInterface {
  constructor(private oauth2Service: OAuth2Service) {}
  
  async use(request: Request, response: Response): Promise<void> {
    // oauth2Service was receiving ContainerInstance instead of OAuth2Service
    if (!this.oauth2Service.isInitialized()) { // Error: isInitialized is not a function
      // ...
    }
  }
}

Solution

Instead of relying on constructor parameter injection, we explicitly retrieve the OAuth2Service from the TypeDI container inside the constructor:

Fixed Code

import { Service, Container } from 'typedi'
import { OAuth2Service } from '../services/OAuth2Service'

@Service()
export default class OAuth2AuthorizationMiddleware implements ExpressMiddlewareInterface {
  private oauth2Service: OAuth2Service

  constructor() {
    // Explicitly get OAuth2Service from the container to avoid injection issues
    this.oauth2Service = Container.get(OAuth2Service)
  }

  async use(request: Request, response: Response): Promise<void> {
    // Now oauth2Service is correctly the OAuth2Service instance
    if (!this.oauth2Service.isInitialized()) {
      // Works correctly
    }
  }
}

Files Modified

server/middlewares/OAuth2AuthorizationMiddleware.ts
- Changed from constructor parameter injection to explicit container retrieval
- Removed debugging console.log statements
server/middlewares/OAuth2CallbackMiddleware.ts
- Applied the same fix for consistency
- Changed from constructor parameter injection to explicit container retrieval

Why This Works

By using Container.get(OAuth2Service) explicitly:

We bypass the problematic parameter injection mechanism
TypeDI correctly resolves the service as a singleton
The same instance that was initialized in app.ts is retrieved
All methods (isInitialized(), createAuthorizationURL(), etc.) are available

Testing

After this fix, the OAuth2 flow should work correctly:

User navigates to /api/oauth2/connect
OAuth2AuthorizationMiddleware successfully retrieves OAuth2Service
PKCE parameters are generated
User is redirected to the OIDC provider
After authentication, callback to /api/oauth2/callback works
OAuth2CallbackMiddleware exchanges the code for tokens
User information is retrieved and stored in session
User is redirected back to the original page

OAUTH2-README.md - Main OAuth2/OIDC documentation
OAUTH2-QUICK-START.md - Quick start guide
OAUTH2-IMPLEMENTATION-STATUS.md - Implementation status

Technical Notes

Why Not Global Middleware Registration?

We could have registered the middleware globally in useExpressServer() configuration, but using @UseBefore() provides:

Better route-specific control
Clearer code organization
Explicit middleware ordering per endpoint

TypeDI Singleton Behavior

The @Service() decorator on OAuth2Service makes it a singleton by default, so:

Container.get(OAuth2Service) always returns the same instance
The instance initialized in app.ts with initializeFromWellKnown() is the same one used in middleware
No duplicate initialization occurs

Date

December 2024

4.3 KiB Raw Blame History