Attach ViewModel method to events in WPF
How do I bind an event in WPF-Control to a method on my ViewModel?
I have a ViewModel:
class MyViewModel {
public string MyText { get; set; }
public void MyMouseHandleMethod(object sender, EventArgs e) { }
}
In the DataTemplate I have:
<TextBlock Text="{Binding Text}">
Now I would like to attach a method to my ViewModel to a TextBlock, something like:
<TextBlock Text="{Binding MyText}" MouseUp="{Binding MyMouseHandleMethod}">
I cannot figure out how to do this without creating a callback in the code.
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2 answers
I have a new solution that works in .NET 4.5+ using a custom markup extension for an event. It can be used with multiple arguments, bindings and other extensions to provide argument values, etc. I explain this in detail here:
http://www.singulink.com/CodeIndex/post/building-the-ultimate-wpf-event-method-binding-extension
Using:
<!-- Basic usage -->
<Button Click="{data:MethodBinding OpenFromFile}" Content="Open" />
<!-- Pass in a binding as a method argument -->
<Button Click="{data:MethodBinding Save, {Binding CurrentItem}}" Content="Save" />
<!-- Another example of a binding, but this time to a property on another element -->
<ComboBox x:Name="ExistingItems" ItemsSource="{Binding ExistingItems}" />
<Button Click="{data:MethodBinding Edit, {Binding SelectedItem, ElementName=ExistingItems}}" />
<!-- Pass in a hard-coded method argument, XAML string automatically converted to the proper type -->
<ToggleButton Checked="{data:MethodBinding SetWebServiceState, True}"
Content="Web Service"
Unchecked="{data:MethodBinding SetWebServiceState, False}" />
<!-- Pass in sender, and match method signature automatically -->
<Canvas PreviewMouseDown="{data:MethodBinding SetCurrentElement, {data:EventSender}, ThrowOnMethodMissing=False}">
<controls:DesignerElementTypeA />
<controls:DesignerElementTypeB />
<controls:DesignerElementTypeC />
</Canvas>
<!-- Pass in EventArgs -->
<Canvas MouseDown="{data:MethodBinding StartDrawing, {data:EventArgs}}"
MouseMove="{data:MethodBinding AddDrawingPoint, {data:EventArgs}}"
MouseUp="{data:MethodBinding EndDrawing, {data:EventArgs}}" />
<!-- Support binding to methods further in a property path -->
<Button Content="SaveDocument" Click="{data:MethodBinding CurrentDocument.DocumentService.Save, {Binding CurrentDocument}}" />
View model method signatures:
public void OpenFromFile();
public void Save(DocumentModel model);
public void Edit(DocumentModel model);
public void SetWebServiceState(bool state);
public void SetCurrentElement(DesignerElementTypeA element);
public void SetCurrentElement(DesignerElementTypeB element);
public void SetCurrentElement(DesignerElementTypeC element);
public void StartDrawing(MouseEventArgs e);
public void AddDrawingPoint(MouseEventArgs e);
public void EndDrawing(MouseEventArgs e);
public class Document
{
// Fetches the document service for handling this document
public DocumentService DocumentService { get; }
}
public class DocumentService
{
public void Save(Document document);
}
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