ViewComponentTagHelper: Allow optional parameters

[pawchen]

Say we have a ViewComponent class

class MyViewComponent
{
    IViewComponentResult Invoke( bool showSomething = false ) { ... }
}

It would be great to just only write <vc:my /> in Razor if one don't want to show that something. Currently you have to write <vc:my show-something="false" />.

[DamianEdwards]

Agreed. No idea how feasible it is, but I agree with the sentiment 😄

[rynowak]

This seems pretty feasible. We need to teach this code about default values. Currently it says that each parameter is a required attribute

[DamianEdwards]

@rynowak candidate for preview2?

[rynowak]

I'm going to move it in and mark it up for grabs. At this point locking down our public APIs and completing the tooling story needs to take priority.

[svallis]

Really looking forward to this fix. As things stand, using the VC tag helper is very dangerous. Add a new parameter to an existing and widely used tag helper and miss updating one of the places it is called and it silently fails while emitting server side markup to the browser. I guess we're too far along now for this to make it in to 2.0.0?

[rynowak]

This is not going to make it for 2.0.0. We don't have time to update tooling at this point.

[Liero]

I believe it should be marked as a bug.

This is working:

@await Component.Invoke(typeof(MyViewComponent));

This is not working

<vc:My />

It is expected behavior and since you do not show any warning, error, debug message, nothing, it upsets a lot of people wondering why the hell the view component is not rendered

[clockwiseq]

So will this make it into the next release?

[dseipp]

Looking for an update on this issue. Will this be added any time soon? Rather frustrating one to deal with.