In Workflow, I'd like my ViewFactory to inject some dependencies (not included in the Rendering) int...

# squarelibraries

[Doug McCluer]

In Workflow, I'd like my ViewFactory to inject some dependencies (not included in the Rendering) into the View it creates. And so I need to be able to pass arbitrary parameters into the ViewFactory. What's the best way to achieve this?

[Doug McCluer]

Extending LayoutRunner with a constructor that accepts more parameters seems to not work.

[Ray Ryan]

We have dagger create the view factory, and inject it into the activity that sets up workflow layout

[Doug McCluer]

That sounds good, but I'm stumbling a bit on the "create the view factory" part.

If I define a ViewFactory like so:

@OptIn(WorkflowUiExperimentalApi::class)
class DiscoverViewFactory(val imageLoader:IImageLoader):ViewFactory<DiscoverRendering> {

	override val type = DiscoverRendering::class

	override fun buildView(
		initialRendering:DiscoverRendering,
		initialViewEnvironment:ViewEnvironment,
		contextForNewView:Context,
		container:ViewGroup?
	):View {
		return DiscoverView(
			imageLoader = imageLoader,
			context = contextForNewView
		)
	}
}

and put an instance of that in the viewRegistry, I'm getting an error saying that bindShowRendering was not called

[Doug McCluer]

what is bindShowRendering exactly?

[Ray Ryan]

It's an extension function that puts your show rendering function where we can find it for updates. You need to call that it on the view before you return it. Looking for an example...

[Ray Ryan]

Just add this:

import com.squareup.workflow1.ui.bindShowRendering

		return DiscoverView(
			imageLoader = imageLoader,
			context = contextForNewView
		).apply {
                  bindShowRendering(initialRendering, initialEnv, ::update)
                }

Where update is whatever function your view defines to receive fresh instances of the rendering.

[Ray Ryan]

grrr, thanks Slack, one sec...

[Doug McCluer]

ok, so the view (or something) needs to define a function with the signature:

(RenderingT, ViewEnvironment) -> Unit

and have the factory do something like

@OptIn(WorkflowUiExperimentalApi::class)
class DiscoverViewFactory(val imageLoader:IImageLoader):ViewFactory<DiscoverRendering> {

	override val type = DiscoverRendering::class

	override fun buildView(
		initialRendering:DiscoverRendering,
		initialViewEnvironment:ViewEnvironment,
		contextForNewView:Context,
		container:ViewGroup?
	):View {
		return DiscoverView(
			imageLoader = imageLoader,
			context = contextForNewView
		).apply {
			bindShowRendering(initialRendering, initialViewEnvironment){ ren:DiscoverRendering, env:ViewEnvironment ->
				showRendering(ren, env)
			}
		}
	}
}

?

[Ray Ryan]

Exactly.

[Doug McCluer]

I see, thanks!

[Ray Ryan]

You also might need to add this to that apply block:

[Ray Ryan]

layoutParams = LayoutParams(MATCH_PARENT, MATCH_PARENT)

[Doug McCluer]

cool, thanks for the tip

[Ray Ryan]

Sure thing, thanks for trying it out

[Doug McCluer]

The idea of a UDF framework that lets me not use Fragments is pretty exciting!