Access a custom controls bindable properties from its xaml - xaml

Question

I want to declare a bindable property in my custom view and link it to the corresponding viewmodel.
I use the MVVM pattern and want to separate ui logic and data logic from eachother. So I keep my status and other data in the viewmodel and update my view according to viewmodel data changes.
This of course should be done by data binding.
Lets say I got the following xaml ...
<?xml version="1.0" encoding="UTF-8"?>
<ContentView xmlns="http://xamarin.com/schemas/2014/forms"
xmlns:x="http://schemas.microsoft.com/winfx/2009/xaml"
xmlns:controls="clr-namespace:MyApp.Views.Controls"
x:Class="MyApp.Views.Controls.MyView"
x:DataType="controls:MyViewVm">
<!--TODO: Content-->
</ContentView>
... with this code behind ...
using System.Runtime.CompilerServices;
using Xamarin.Forms;
using Xamarin.Forms.Xaml;
namespace MyApp.Views.Controls
{
[XamlCompilation(XamlCompilationOptions.Compile)]
public partial class MyView : ContentView
{
public static readonly BindableProperty StatusProperty = BindableProperty.Create(nameof(Status), typeof(MyStatus), typeof(MyView));
public MyStatus Status
{
get => (MyStatus)GetValue(StatusProperty);
set => SetValue(StatusProperty, value);
}
public MyView()
{
InitializeComponent();
}
protected override void OnPropertyChanged([CallerMemberName] string propertyName = null)
{
base.OnPropertyChanged(propertyName);
switch (propertyName)
{
case nameof(Status):
// TODO: Do styling ...
break;
}
}
}
}
... and this viewmodel and status enum:
namespace AbrechnungsApp.Views.Controls
{
public class MyViewVm : ViewModelBase
{
public MyStatus Status { get; set; }
}
public enum MyStatus
{
Enabled,
Disabled,
Readonly
}
}
Now the question is:
How do I link my viewmodels Status property to my views Status bindable property?

Answer 1

I typically create a helper property to cast BindingContext to the appropriate VM class:
private MyViewVm VM => (MyViewVm)BindingContext;
Then get/set VM properties in the bindable property:
public static readonly BindableProperty StatusProperty =
BindableProperty.Create(
nameof(Status), typeof(MyStatus), typeof(MyView),
propertyChanged: (binding, old, new) =>
{
// Needed if your XAML uses two-way binding.
Status = new;
});
public MyStatus Status
{
get => VM.Status;
set => VM.Status = value;
}