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mvvmdrag-and-dropbinding

Data binding manually update in WPF MVVM

My ViewModel:

class ViewModel
{
public string FileName {get;set;}
}

and in my View I bind a label's content to ViewModel's FileName.

now When I do drag-drop a file to my View, How can I update the label's Content property, so that the ViewMode's FileName also get updated via binding?

Directly set the label's Content property won't work, it just simply clear the binding.

Solution

  • 3 quick choices... (Make sure the class implements INotifyPropertyChanged, and FileName is raising this event.)

    1. You can simply pull the VM out of the View's DataContext and during the Drag-and-Drop event set the FileName property of the ViewModel.

    2. Use an AttachedBehavior to allow the Event (Drag-and-Drop) to be used like a Command (Link)

    3. Use a Messenger pattern, like MVVMLight's Messenger, to send a Message from the View to the ViewModel and handle the Message on the VM like you would a Command Action.