How to get the count of selected rows of datagrid following MVVM?

Question

I'm trying to get the count of the selected rows of a WPF datagrid and display it in a textblock.

How can I do that following MVVM pattern?

Answer 1

You could refer to the code below.
Xaml:

  <StackPanel>  
        <DataGrid AutoGenerateColumns="False"  Height="200" x:Name="dg" Width="350" ItemsSource="{Binding Users}" SelectionMode="Extended"   
                  SelectedItem="{Binding SelecedItme ,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}">  
                <DataGrid.Columns>  
                <DataGridTextColumn Header="ID"  Binding="{Binding Id,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"/>  
                <DataGridTextColumn Header="Name" Binding="{Binding Name,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"/>  
            </DataGrid.Columns>  
            </DataGrid>  
        <TextBlock x:Name="tb"  Text="{Binding ElementName=dg, Path=SelectedItems.Count, Mode=OneWay,UpdateSourceTrigger=PropertyChanged}" Width="350" Background="AliceBlue"/>  
    </StackPanel>  

Codebedhind:

260501-codebehind.txt

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Answer 2

Hi,
in MVVM you can use an attached property to get SelectedItems directly from DataGrid.

Demo:

<Window x:Class="WpfApp1.Window028"  
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"  
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"  
        xmlns:d="http://schemas.microsoft.com/expression/blend/2008"  
        xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"  
        xmlns:local="clr-namespace:WpfApp028"  
        mc:Ignorable="d"  
        Title="donbradman-4481_221115" Height="450" Width="800">  
  <Window.DataContext>  
    <local:ViewModel/>  
  </Window.DataContext>  
  <Grid>  
    <Grid.RowDefinitions>  
      <RowDefinition/>  
      <RowDefinition Height="Auto"/>  
    </Grid.RowDefinitions>  
    <DataGrid ItemsSource="{Binding View}" local:ViewModel.AttProp="True"/>  
    <StackPanel Grid.Row="1" Orientation="Horizontal" Margin="5">  
      <Label Content="Selected Rows Count: "/>  
      <TextBlock Text="{Binding RowCount}" Margin="5"/>  
    </StackPanel>  
  </Grid>  
</Window>  

and ViewModel.

Result: