advanced patterns with TypeScript Class Decorators in Dependency Injection Context - best practices for?
I'm currently working with TypeScript (v4.5) and using the NestJS framework for building a backend application. I have a service class where I'm trying to use a custom decorator to inject dependencies, but I’m running into unexpected behavior. Specifically, when I apply my decorator, it seems to override the constructor parameters, and I'm unable to access the injected services. Here’s a simplified version of the code: ```typescript import { Injectable, Inject } from '@nestjs/common'; function MyCustomDecorator() { return function (target: any, key: string, descriptor: PropertyDescriptor) { // Adding custom behavior const originalMethod = descriptor.value; descriptor.value = function (...args: any[]) { console.log('Called with args:', args); return originalMethod.apply(this, args); }; }; } @Injectable() export class MyService { constructor(@Inject('MyDependency') private myDependency: any) {} @MyCustomDecorator() public myMethod(arg1: string) { console.log('myMethod called with:', arg1); } } ``` When I call `myMethod`, I expect it to receive `arg1` and execute normally. However, I get the following behavior: ``` behavior: want to read properties of undefined (reading 'myDependency') ``` It appears that the context of `this` is lost when the method is invoked through the decorator. I’ve tried binding the method within the decorator but still face the same scenario. I've also checked that the service is correctly registered in the module. Has anyone else faced this scenario? How can I ensure that the method retains its original context and accesses the injected dependencies properly? What are your experiences with this?