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POTriggering Commands from the ViewModel in WPF with MVVM
 

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    <p>I have created a few Custom Controls (NOT UserControls) with bind-able "ClearCommand" ICommand dependency properties. This property will do exactly what it sounds: it will clear all the values from the control (textboxes, etc). I also bind (some) of those same properties to the VM I describe below.</p> <p>Now I'm stuck trying to trigger the ClearCommand in those controls in the following MVVM scenario:</p> <p>I've added a few such controls into my View. The View also includes a "Save" button that binds to my ViewModel's <code>SaveCommand</code> <code>DelegateCommand</code> property. </p> <p>What I need to happen is that, upon a successful save, the VM should trigger the <code>ClearCommand</code> on those controls found in the View.<img src="https://i.stack.imgur.com/oES6U.png" alt="enter image description here"></p> <p><strong>UPDATE</strong></p> <p>I've added code examples below. I have a few controls that resemble the ExampleCustomControl. Also, just to note, I am open to restructuring some of this if it's completely off.</p> <p>Example Control snippet:</p> <pre><code>public class ExampleCustomControl : Control { public string SearchTextBox { get; set; } public IEnumerable&lt;CustomObject&gt; ResultList { get; set; } public ExampleCustomControl() { ClearCommand = new DelegateCommand(Clear); } /// &lt;summary&gt; /// Dependency Property for Datagrid ItemSource. /// &lt;/summary&gt; public static DependencyProperty SelectedItemProperty = DependencyProperty.Register("SelectedItem", typeof(CustomObject), typeof(ExampleCustomControl), new PropertyMetadata(default(CustomObject))); public CustomObject SelectedItem { get { return (CustomObject)GetValue(SelectedCustomObjectProperty); } set { SetValue(SelectedCustomObjectProperty, value); } } public static DependencyProperty ClearCommandProperty = DependencyProperty.Register("ClearCommand", typeof(ICommand), typeof(ExampleCustomControl), new PropertyMetadata(default(ICommand))); /// &lt;summary&gt; /// Dependency Property for resetting the control /// &lt;/summary&gt; [Description("The command that clears the control"), Category("Common Properties")] public ICommand ClearCommand { get { return (ICommand)GetValue(ClearCommandProperty); } set { SetValue(ClearCommandProperty, value); } } public void Clear(object o) { SearchTextBox = string.Empty; SelectedItem = null; ResultList = null; } } </code></pre> <p>Example View snippet:</p> <pre><code>&lt;Grid HorizontalAlignment="Stretch" VerticalAlignment="Stretch"&gt; &lt;Grid.RowDefinitions&gt; &lt;RowDefinition Height="*" /&gt; &lt;RowDefinition Height="30"/&gt; &lt;/Grid.RowDefinitions&gt; &lt;control:ExampleCustomControl Grid.Row="0" SelectedItem="{Binding Selection, UpdateSourceTrigger=PropertyChanged}" /&gt; &lt;Button Grid.Row="1" x:Name="ResetButton" Command="{Binding SaveCommand}"&gt; Save &lt;/Button&gt; &lt;/Grid&gt; </code></pre> <p>Example ViewModel:</p> <pre><code>public class TestViewModel : WorkspaceTask { public TestViewModel() { View = new TestView { Model = this }; SaveCommand = new DelegateCommand(Save); } private CustomObject _selection; public CustomObject Selection { get { return _selection; } set { _selection = value; OnPropertyChanged("Selection"); } } public DelegateCommand SaveCommand { get; private set; } private void Save(object o) { // perform save // clear controls } } </code></pre>
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    1. USDave Clemmer
    1. USAlex
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    1. COTypically, my commands are on my ViewModel. From the ViewModel, you are able to call `MyCommand.Execute();`. If that is not how your project is structured, please post some code to clarify.
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      1. UScadrell0
    2. COAs a quick workaround you could set the PropertyChangedCallback in the PropertyMetadata when you register SelectedIOtemProperty and in the callback, have it clear everything you want. I would however advise having a think about restructuring your setup and putting the clear in the VM along with all the bound properties.
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      1. USHAdes
    3. COMy issue with having all of the ExampleCustomControl's properties bound to a viewmodel is reuse. I want the search logic/etc sitting in the custom control and I want to be able to reuse the same control in a few different views.
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