[feat] Composition through properties decorator

I’m submitting a…

[ ] Regression 
[ ] Bug report
[x] Feature request
[ ] Documentation issue or request
[ ] Support request => Please do not submit support request here, instead post your question on Stack Overflow.

Current behavior

Right now if you’re extending classes and want to use some “objects” in the “parent” class, you have to pass them individual from the child to parent. DI doesn’t handle this behaviour.

Expected behavior

I would like to see something different than DI through constructor, so Composition as property decorator:

export class Foo {
	@Composition();
	protected bar: Bar;

	// logic
}

export class FooChild extends Foo {
	constructor(private ownBar: Bar) {
		super();
		console.assert(this.ownBar === this.bar, 'How does it feel?');
	}
}

Minimal reproduction of the problem with instructions

None.

What is the motivation / use case for changing the behavior?

Even better/fancy/sexy dependency injection. This will prevent us to pass deps through constructor, code will looks much more cleaner, less effort.

Decorator Composition might also takes a some params, like Model from which we would like to get type.

What do you think guys?

Environment

Nest version: 5.1.0

 
For Tooling issues:
- Node version: v8.11.2  
- Platform: Linux  

Others:

[kamilmysliwiec]

see #1172

[cojack]

@kamilmysliwiec did I told you that I love you? ❤️