How to get ContentPage's BindingContext from ContentView?

Question

I have the following Contentpage.content, where I set certain binding context.

<StackLayout>
    <local:Post />  
    <local:Comments />
</StackLayout>

In Post.xaml.cs (ContentView), I've tried to get the binding context of the ContentPage this way but it doesn't work.

BindingContext = (PostViewModel)Parent.BindingContext;

How can I get the binding context of the ContentPage if I'm standing in a ContentView?

Solution

By the time your constructor is called, the BindingContext might not be initialised yet.

So, you should wait for the BindingContext being changed to perform operations on it.

I think the answer is OnBindingContextChanged event. https://developer.xamarin.com/api/member/Xamarin.Forms.View.OnBindingContextChanged()

Little sample:

        protected override void OnBindingContextChanged ()
        {
            base.OnBindingContextChanged ();

            //BindingContext should not be null at this point
            // and you may add your code here.
        }

Note: If you have a ContentView inside a ContentPage, unless explicitly set by another Control (like when using an ItemTemplate for a ListView) or by your code, the BindingContext of the ContentView is the same as the ContentPage.

So, it shouldn't be necessary to call "Parent".

Let me know if more clarification is needed.