Signature Mismatch in MiddlewareInterface

[JD-Robbs]

Consider the following code (note the Request/Response type hints):

export class MyMiddleware implements MiddlewareInterface {
    use(request: Request, response: Response, next?: Function): any {

Compiling throws the following error:

error TS2420: Class 'MyMiddleware' incorrectly implements interface 'MiddlewareInterface'.
  Types of property 'use' are incompatible.
    Type '(request: Request, response: Response, next?: Function) => any' is not assignable to type '{ (request: any, response: any, next?: (err?: any) => any): any; (context: any, next: (err?: any)...'.
      Types of parameters 'response' and 'next' are incompatible.
        Type '(err?: any) => Promise<any>' is not assignable to type 'Response'.
          Property 'status' is missing in type '(err?: any) => Promise<any>'.

This, however, works:

export class MyMiddleware implements MiddlewareInterface {
    use(request: any, response: any, next?: Function): any {

I tracked the issue to the second (Koa) signature in MiddlewareInterface (removing it fixes the above but, obviously, won't make Koa happy). It looks like my code makes the TypeScript compiler think I'm trying to implement the second signature.

While I tried changing/adding signatures in MiddlewareInterface, I couldn't get it to compile.

[pleerock]

Not sure what is possible there. I know about this issue with typescript, one solution can be if we create two separate interfaces KoaMiddlewareInterface and ExpressMiddlewareInterface instead of MiddlewareInterface. If you can come to solution with MiddlewareInterface please let me know

[JD-Robbs]

If I can work out a way to keep it all in one interface, I'll let you know. I'll take another look and maybe check if anyone on StackOverlow has any ideas.

[marshall007]

@JD-Robbs I was able to get it to compile by overloading the method on my custom class with a more generic signature:

@Middleware()
export class CustomerHeader implements MiddlewareInterface {

  use(request: any, response: any, next?: (err?: any) => any): any;
  use(request: Request, response: Response, next?: NextFunction): any {
    // ...
    next();
  }

}

@pleerock I think if you annotate MiddlewareInterface with the additional overloads it should allow users to implement the method with or without typed parameters.

[pleerock]

new middleware interface signatures are being added in #119

[pleerock]

middlewares now have separate signatures in 0.7.0

[github-actions]

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