Bind before setting content

[MrJul]

Hello,

When using cal:View.Model, I think the view should be bound to the VM before the control is assigned the view. Basically, it means swapping the calls to SetContentProperty and ViewModelBinder.Bind in View.cs:292.

Why? I'm currently getting "temporary" binding errors because when the view is initially created, the parent DataContext is used - just before being set correctly at the next line. Additionally, this improves performance since there is no DataContext changes: the various controls don't have to be completely bound twice.

I'm using WPF in .NET 4.5.

Note: I'm currently working around this problem by setting the data context in ViewLocator.LocateForModel, but it feels hacky.

[remcoros]

Also here: https://github.com/Caliburn-Micro/Caliburn.Micro/blob/master/src/Caliburn.Micro.Platform/View.cs#L312

[nigel-sampson]

It's a possibility, my only concern here is that we're already seeing some weird behavior such as #92 when the visual tree is collapsed, if the view isn't in the true visual tree then I worry it would exacerbate this.

[MrJul]

@nigel-sampson #98 is this issue :)

I understand this can have an impact on conventions.
I'm not using them because of issues like the one you mentioned (conventions not being applied on a collapsed element), but that doesn't give me the right to force everyone not to use them. Maybe as an option, disabled by default?

[nigel-sampson]

You're right, I'm an idiot, the issue I was referring to was #92.

I may need to some experiments to check the behaviour of BindingScope between platforms and this seems to be mostly an issue in WPF.

[nigel-sampson]

Have run into a timing issue in #349 where this approach solved the problem. Mostly due to the lack of Loaded event in Xamarin.Forms. I think doing this for perf is a real consideration for 4.0.0.