I stumbled across this question but I don't think I want to use an alias
I want to extend the express anyFilesInterceptor so I can work with a custom file object. I am not sure how to extend a decorator in NestJS.
So as a work around I tried decorator composition from another question. However, I am getting an error just trying to create a very basic (example in documentation) decorator
import { applyDecorators, createParamDecorator, ExecutionContext } from "@nestjs/common";
import { AnyFilesInterceptor } from "@nestjs/platform-express";
export function Test() {
return applyDecorators(
AnyFilesInterceptor,
TestDecorator
)
}
export const TestDecorator = createParamDecorator(
(data: string, ctx: ExecutionContext) => {
const request = ctx.switchToHttp().getRequest();
const user = request.user;
return data ? user?.[data] : user;
},
);
Now I can see from other discussions and the function naming that AnyFilesInterceptor is a mixin that returns a class while TestDecorator created by createParamDecorator likely only works on parameters.
Does NestJS have a way to create a class decorator? Or to extend existing decorators?
actually the AnyFilesInterceptor is a function itself that produces an interceptor (which is any class that implements NestInterceptor).
You can see it by the usage: while 'other' interceptors may be used by simply giving the class to the UseInterceptor() decorator, this interceptor needs invocation (without new keyword).
Example:
@UseInterceptor(RegularInterceptor)
//or
@UseInterceptor(new RegularInterceptor())
// AnyFilesInterceptor is a function returning a class
@UseInterceptor(AnyFilesInterceptor())
//or
@UseInterceptor(new (AnyFilesInterceptor())({/* some multer options here */))
so basically if you want to extend the AnyFilesInterceptor you simply need to define a class inteceptor of your own:
export class MyAllFilesInterceptor extends AnyFilesInterceptor() {
// YOU MUST OVERRIDE THE `intercept` METHOD!
// also, give options to the `AnyFilesInterceptor` method if you wish
}