DataTemplate button command from binding

Question

I'm using Wpf and I'm passing a List<Value> to a <ItemsControl> in the xaml. I would like to bind the string in the Value Object to the Command of a Button. This xaml part looks like this:

 <Grid Margin="0,0,2,0"> <Grid Margin="10"> <ItemsControl Name="details"> <ItemsControl.ItemTemplate> <DataTemplate> <Grid Margin="0,0,0,5"> <Grid.ColumnDefinitions> .... </Grid.ColumnDefinitions> ... <Button Grid.Column="2" Content="{Binding ButtonContent}" Visibility="{Binding ButtonVisibility}" Command="{Binding ButtonClickMethod}" /> ...

My Value Class looks like this:

public class Value { ... public string ButtonClickMethod { get; set; } }

I'm setting the string link this:

v.ButtonClickMethod = "RelatedActivityId_OnClick";

And the Method is in the same class and looks like this:

private void RelatedActivityId_OnClick(object sender, RoutedEventArgs e) { MessageBox.Show("RelatedActivityId_OnClick"); }

Everything besides this is working properly and unses the same Object for the binding. What am I doing wrong?

So the string ButtonClickMethod contains the name of the method to execute? — brunnerh
– brunnerh, Commented Jul 19, 2016 at 14:39

Community · Accepted Answer · 2017-05-23 12:22:34Z

The Command property of the Button is of type ICommand so you cannot bind it to a string value.

You need to update your ButtonClickMethod to be of type ICommand or create a new property to bind you Command to.

See this answer for a sample implementation of ICommand.

If you need the button to execute code based on a parameter (string value?) then you can use the CommandParameter property, then use that paramters in your Command handler.

public class Value { public Value() { ButtonCommand = new RelayCommand((a) => true, CommandMethod); } public RelayCommand ButtonCommand {get; set; } public string ButtonClickMethod { get; set; } private void CommandMethod(object obj) { MessageBox.Show(obj?.ToString()); } }

and the XAML:

<Button Grid.Column="2" Content="{Binding ButtonContent}" Visibility="{Binding ButtonVisibility}" Command="{Binding ButtonCommand}" CommandParameter="{Binding ButtonClickMethod}" />

(If the goal is the execution based on a dynamically set value then just assigning a different command is way easier than using strings and reflection anyway.)
i'm hoping he can use the parameter to decide which method to call rather than find it though reflection... assuming there is a finite amount of methods that he can call into.

OrMiz · Accepted Answer · 2016-07-19 14:48:26Z

The Button.Command property binds only to objects which implement the ICommand interface. If you want to invoke a method which its name is ButtonClickMethod, you will have to:

Create a class which implements ICommand interface.
Create a object of that class and bind it to your button (bind it to Button.Command).
Pass the Value.ButtonClickMethod as a CommandParameter to your ICommand object.
Use this to invoke any method you would like to.

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DataTemplate button command from binding

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