当TextBox失去焦点时在ViewModel中运行函数吗？

Question

I currently have the following code to define a TextBox in a grid (the grid is populated based on data, so is also inside a DataTemplate):

<TextBox 
    MinWidth="120" 
    Text="{Binding BatchNumber, Mode=TwoWay}"
    ToolTip="Redacted" 
    IsTabStop="True"
    MaxLength="32" 
    <!-- LostFocus="TextBox_LostFocus" -->
/>

I'd like to run a function in my ViewModel when the textbox loses focus. Using the LostFocus property, and binding to a function name, causes a runtime error of:

A 'Binding' can only be set on a DependencyProperty of a DependencyObject

As such, I'm looking for details on how to run a ViewModel function when focus is lost.

Answer 1

In your ViewModel try to add:

//Public property
public ICommand MyCommand { get; set; }

//In the constructor 
MyCommand = new RelayCommand(DoSometing);

//Private method to handle lost focus
private void DoSometing(){
//Do someting
}

Then call MyCommand in your xaml.

LostFocus="{Binding MyCommand}"