decorator-decoupler

Work in progress

Use decorator-based frameworks without polluting your core

How to Install

npm i decorator-decoupler

How to use it

Marks your class, parameters and methods of interest with the proper decorator:

@MetaClass()
export class MyClass {
  constructor(@MetaCtorParam(MyParamSymbol) param: string) {
    ...
  }

  @MetaMethod()
  myMethod(
    @MetaParam(MyOtherParamSymbol) param: number,
  ): void {
    ...
  }
}

Then, apply the decorator of the framework of your choice at the beginning of you app!

import { applyMetaClass } from 'decorator-decoupler';
import { Injectable, Inject } from '@nestjs/core';

applyMetaClass(Injectable);
applyMetaCtorParam(Inject);

Suppose for a certain class you want to apply a different decorator other than the default one informed in applyMetaClass. In this case, before calling it, you may call prepareMetaClass:

prepareMetaClass(MyScopedClass, Injectable({ scope: Scope.Request }));
applyMetaClass(Injectable);

In the above example, all classes marked with @MetaClass() will be marked with @Injectable(), except for MyScopedClass, that will be marked with @Injectable({ scope: Scope.Request }). You may also prepare multiple decorators for the same class, and it'll be applied in order.

There are also prepare methods for each type of decorator.

But why?

The idea here is to totally isolate your core code, where your main structure and business rule is, from infrastructure details. In the example above, nestjs is a great framework but is an infrastructure library. If you want to change the controller scheme of your application, you need to remove nestjs decorators from your core code, and probably change some decorator applying logic, not only replacing it. With decorator-decoupler, you can concentrate all that logic in the entrypoint or infrastructure layer, making the transition between different frameworks a lot easier.

License

Licensed under MIT.