Question

I am using WPF and PRISM framework for my application. The pattern I am using is MVVM (Model – View – ViewModel) and I am trying to bring the MouseLeftButtonUp event from the code-behind in the View to the ViewModel (so the event will be according the MVVM rules). For now I have this:

View.xaml:

<DataGrid x:Name="employeeGrid" Height="250" Margin="25,0,10,0" ItemsSource="{Binding DetacheringenEmployeesModel}" IsReadOnly="True" ColumnHeaderStyle="{DynamicResource CustomColumnHeader}" AutoGenerateColumns="False" RowHeight="30">
        <i:Interaction.Triggers>
            <i:EventTrigger EventName="MouseLeftButtonUp">
                 <i:InvokeCommandAction Command="{Binding EmployeeGrid_MouseLeftButtonUp}" />
            </i:EventTrigger>
        </i:Interaction.Triggers>
<DataGrid.Columns>

View.xaml.cs (code-behind):

public partial class UC1001_DashBoardConsultants_View
{
    public UC1001_DashBoardConsultants_View(UC1001_DashboardConsultantViewModel viewModel)
    {
            InitializeComponent();
            DataContext = viewModel;
    }
}

ViewModel.cs:

 public void EmployeeGrid_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
 {
     // insert logic here
 }

The main idea is, when I click on a cell in the DataGrid, the event will fire. I first tried it in the code behind, and it worked. I got so far with the EventTriggers, but when I debug and click on a cell, my debugger doesn’t come into the method.

Does anyone have an idea how to fix this? Thanks in advance!

PS: Does it also work with the (object sender) parameter when I do it like that? Because I need the DataGrid in my ViewModel to get the ActiveCell I just clicked on.

EDIT:

The event-binding worked with the Command!

I have this in my DataGrid:

<DataGridTextColumn Header="Okt" Width="*" x:Name="test" >
     <DataGridTextColumn.ElementStyle>
           <Style TargetType="{x:Type TextBlock}">
             <Setter Property="Tag" Value="{Binding Months[9].AgreementID}"/>

How can I bind the Tag property to the ViewModel? I know it’s already bound from the ViewModel, but as you can see the value comes from an Array/List and per column the value is different.

Answer 1

InvokeCommandAction requires the ICommand to be bound not an event handler as you’ve bound (EmployeeGrid_MouseLeftButtonUp).

So you can introduce a command in ViewModel and bind to it:

View Model:

public ICommand SomeActionCommand { get; set; }

XAML:

<i:InvokeCommandAction Command="{Binding SomeActionCommand}" />