InitializeComponent() or set BindingContext? What should be called first?

[Marioo1357]

Hi, I wonder what in xaml.cs constructor should be called first?

InitializeComponent is called first in MAUI samples.
Also, I saw few tickets/issues where setting BindingContext right after InitializeComponent() was the solution:

• [iOS] RefreshView Loading Indicator Stuck with CollectionView #28169
• InitalizeComponent / Bindings operate on DataContext from previous invocation wpf#7352

I have a question, is it really matter?

[bzd3y]

To my understanding, the only place where this matters is when it comes to observing binding context changes. I think that if you set it before InitializeComponent then anything subscribing to those events won't get notified because by the time they have subscribed, the binding context has already changed. If you set it afterward, then they should be subscribed and the change can be observed.

[Marioo1357]

Thats true.
But as a user, as a contract consumer I dont know what implementations all Maui controls has. So as I understand it would be better to always set BindingContext after call InitializeComponent()?

[bzd3y]

I don't know. Somebody with more knowledge will probably need to answer that. To my understanding it just isn't that simple. If you want things in your view to detect that the binding context is changing from null to something else, then yes. If that doesn't matter then I don't think there is a general rule.

Speaking of knowing how things are implemented, some given control could throw an exception if it's binding context was set before and some other control might throw one if it is set after.

Personally, I default to setting it before so that when the view is initialized it is already in its initial state.

[stephenquan]

Are you referring to the ContentPage? If so, I recommend setting BindingContext in XAML so that x:DataType can be set simultaneously.

[bzd3y]

When possible, sure. But you can't always do that, like when using an MVVM pattern where the object being bound to might get passed to you.

[Marioo1357]

Is setting from xaml support DI? How to do it?

[bzd3y]

Setting it in XAML wouldn't really be compatible with DI directly. But what you would need is a property on your view for your view model and set that in its constructor. And then in the XAML you'd bind the binding context to that. But by the time you are doing that, I'm not sure why you wouldn't just set the binding context in the constructor to what DI passed in.

That is what I do, and, as I said above, I generally do it before the call to InitializeComponent().

If you were relying on BindingContextChanged somewhere in the view and you need it to catch that initial change, then you might want to do it after.

[Marioo1357]

I have the same perspective as you. I prefere to set binding context before initialize component. However, there are some bugs where revert this order helped. I think Ill just analyze what those controls have inside

[bzd3y]

Exactly. There isn't a single correct way to do it because it depends on how things are implemented.