Add step change and disabled step option

[rluvaton]

Add step change event to wizard #176
Fix wizard component test file misleading comment

[rluvaton]

In case of approval need to update the README file of the new changes

[madoar]

I believe it's a good idea to add a stepChanged output emitter.
I'm just not sure if we should emit the WizardStep object, to which the wizard changed.
The reason here is, that the WizardStep is meant as an wizard internal class, which provides a lot of fields which shouldn't be changed outside of the wizard (for example the field selected shouldn't be changed from outside the wizard).

In addition the output doesn't forward information such as the navigation direction, the source step etc, which is often also of interest.
I think it's better to brainstorm some more about which information the output should forward and how it should look like.

[rluvaton]

You’re absolutely right,
What about this?

{
  from: number,
  to: number,
  direction: MovingDirection
}

[madoar]

Sounds good.
Are there maybe some other fields we want to pass to the receiver of the output emitter (just asking would be bad if we missed something)?

[rluvaton]

I don’t think it’s necessary but you can provide source and isTrusted:

Source

source of the changed step: from where, is it from clicking next/prev/go-to step or by clicking the step title

isTrusted

Is the change came from our library:

• Next/Prev/Go To step directives
• step title
• or programmatically

[madoar]

This should be moved to the navigation modes

[rluvaton]

I thought of that at first but then for each type of navigation mode (strict and etc) need to be the same code, so why don’t we make it once in a service that have current index already

[madoar]

This will change with #166, where this redundant code is likely to be moved to BaseNavigationMode.
We just need to wait until @earshinov has some free time again to continue working on the PR.

[madoar]

Why is an additional Subject required?
Isn't the output sufficient?

[rluvaton]

I don’t think you can use Output in an Angular service

[madoar]

How do you access the Subject from the angular service?
Hasn't it the same issue?

[rluvaton]

You don’t you have limited options in purpose.

You only need 2 usages with this

1. Update step
2. Listen to updates

Update step:
When changing current index it will emit the value

Listen to changes:
You have a get variable/function for getting the observable

[madoar]

Can't you then create the Subject in your service and wire the emitted step change to the subject by a provided function to the output?
I.e. like this:

stepChanged(event): void {
   this.service.subject.next(event);
}

<wizard (stepChanged)="stepChanged($event)">
   ...
</wizard>

[rluvaton]

Where is the step changed function location? is it in the wizard.component.ts because you can create instance of yourself

Is the user have this function? Then we don’t provide him the subject only update and listening, can you please give me another example?

[rluvaton]

And I think using an angular built in component tool is better for understanding and simpler

[madoar]

Here a more detailed example:

The service

@Injectable()
export class Service {
   public subject = new Subject();
}

The application component

@Component({
   template: `
      <wizard (stepChanged)="stepChanged($event)">
         ...
      </wizard>
   `
})
export class AppComponent {
   constructor(private service: Service) {}

   public stepChanged(event): void {
      this.service.subject.next(event);
   }
}

[madoar]

I agree, that adding functions directly to a library is often faster to implement and second easier to use from inside an end-application.

The issues for the library developers are, that each additional function needs to be documented and maintained.
In addition this easily leads to cluttering of the library, where a lot of functions are added to a library that are not often needed or which can be easily realized from outside of the library.

[rluvaton]

So at least make the subject private and leave the functions for interact with the subject without changing the subject itself, this way you don’t open the subject for unwanted changes

[madoar]

I don't understand what a disabling a step does?

[rluvaton]

Preventing you from entering this step

Use case:

• you need to choose between 2 options each option make different step enabled

I needed to use this option actually

[madoar]

This sounds like you want to use the inputs [canEnter] and [canExit] of the wizard steps?

[rluvaton]

Not precisely, because disabled is a state, it’s need to have a style and custom behavior:

Like when going to next step it will jump over the disabled one.

And other libraries have this too...

[madoar]

Ok, I understand.
Then the questions are:

• how do you define a step as disabled?
• how should the wizard react when the user wants to navigate to a disabled step?
  Is it always possible to skip the step? If yes, in which direction? Are there other actions the wizard could do in instead of entering a disabled step?

In any case I think supporting disabled steps should be moved to its own PR.

[madoar]

Closed because of inactivity