Document and add example for using "select"

[rubyboy]

Document (in README) and add example (in angular-redux-example?) for using the "select" observable technique
Implementation done in this PR: #12

CC @micha149

[rubyboy]

Added example of using the new "select" in the angular-redux-example:
Commit: InfomediaLtd/angular2-redux-example@a6d7a07

    private parts$ = null;
    private partsInCart$ = null;

    constructor(appStore:AppStore, partActions:PartActions, cartActions:CartActions) {
        this.parts$ = appStore.select("parts");
        this.partsInCart$ = appStore.select(partsInCartSelector);

[micha149]

You could do something like passing the currentUser$ observable directly into the user component and let the component mark for change detection if the observable changes…

  constructor(private cd: ChangeDetectorRef) {}

  ngOnInit() {
    this.data.subscribe(() => {
      this.cd.markForCheck(); // marks path
    })
  }

This is were working with observables really gives a benefit on performance…
http://blog.thoughtram.io/angular/2016/02/22/angular-2-change-detection-explained.html

[micha149]

It would make sense to place all selector functions into separate files. So, you don't have to worry where to find your required data in the state. Just include the respective selector function and use it. A folder named selectors as a sibling to reducers would be a common place for such files.

[rubyboy]

Agree about separating selectors into files. Absolutely makes sense. Will do that tomorrow.

Re the change detection, I quite like the fact that the observable itself triggers change detection when data flows in and it's all internal to the mechanism. This way it's all handled nicely by Angular without boilerplate code.

One other issue I was looking at and didn't find a solution was the state that is used in functions. Look at the AdminComponent and how is uses the filmFilter. Any idea how to use this with a selector? (I can't simply use async because it uses the filter as a param to a function. Also, it is used as a toggle for UI text (on/off) ).

[micha149]

Why not writing the value to a class property on update?

[rubyboy]

That's what it does right now, using a "subscribe" :)

[micha149]

Yeah, that's what I meant. I didn't looked at the code since yesterday evening. But the night brought me no better solution 😄 I think this is not a bad solution. Why enforcing to use observables everywhere, also when it makes no sense?

[rubyboy]

You're right! :)