How to make WPF DataGridCell ReadOnly?

Question

I understand you can make the whole DataGrid or a whole column readyonly (IsReadOnly = true). However, at cell level this property is ready only. But I do need this level of granularity. There is blog about adding IsReadOnly to a row by changing the source code in old days when DataGrid was public domain, but now I don't have source code for DataGrid. What's workaround?

Making cell disabled (IsEnabled=false) almost meets my need. But the problem is that you can't even click the disabled cell to select the row (I have full row selection mode).

EDIT: Since nobody has responded to this question, so I guess it's not an easy fix. Here is a possible workaround: Make the cell uneditable. The only problem is that clicking the cell doesn't select the row. I just noticed that MouseDown or MouseUp event of the DataGrid is still fired when the disabled cell is clicked. In this event handler, if I could figure out the row it clicked, I could select the row programmatically. However, I couldn't figure out how to find the underlying row from DataGrid.InputHitTest. Can somebody please give me some tip?

Answer 1

I've encountered the same problem, the cell should be read-only in some rows but not in the others. Here is a workaround solution:

The idea is to dynamically switch the CellEditingTemplate between two templates, one is the same as the one in the CellTemplate, the other is for editing. This makes the edit mode acts exactly the same as the non-editing cell although it is in edit mode.

The following is some sample code for doing this, notice that this approach requires DataGridTemplateColumn:

First, define two templates for read-only and editing cells:

<DataGrid>
  <DataGrid.Resources>
    <!-- the non-editing cell -->
    <DataTemplate x:Key="ReadonlyCellTemplate">
      <TextBlock Text="{Binding MyCellValue}" />
    </DataTemplate>

    <!-- the editing cell -->
    <DataTemplate x:Key="EditableCellTemplate">
      <TextBox Text="{Binding MyCellValue}" />
    </DataTemplate>
  </DataGrid.Resources>
</DataGrid>

Then define a data template with additional ContentPresenter layer and use Trigger to switch the ContentTemplate of the ContentPresenter, so the above two templates can be switched dynamically by the IsEditable binding:

<DataGridTemplateColumn CellTemplate="{StaticResource ReadonlyCellTemplate}">
  <DataGridTemplateColumn.CellEditingTemplate>
    <DataTemplate>
      <!-- the additional layer of content presenter -->
      <ContentPresenter x:Name="Presenter" Content="{Binding}" ContentTemplate="{StaticResource ReadonlyCellTemplate}" />
      <DataTemplate.Triggers>
        <!-- dynamically switch the content template by IsEditable binding -->
        <DataTrigger Binding="{Binding IsEditable}" Value="True">
          <Setter TargetName="Presenter" Property="ContentTemplate" Value="{StaticResource EditableCellTemplate}" />
        </DataTrigger>
      </DataTemplate.Triggers>
    </DataTemplate>
  </DataGridTemplateColumn.CellEditingTemplate>
</DataGridTemplateColumn>

HTH

Answer 2

After much searching and experimentation using IsTabStop = False and Focusable = False works best for me.

<DataGridTextColumn Header="My Column" Binding="{Binding Path=MyColumnValue}">
    <DataGridTextColumn.CellStyle>
        <Style TargetType="DataGridCell">                                    
            <Style.Triggers>
                <DataTrigger Binding="{Binding Path=ReadOnly}" Value="True">                                                    
                    <Setter Property="IsTabStop" Value="False"></Setter>
                    <Setter Property="Focusable" Value="False"></Setter>
                </DataTrigger>
            </Style.Triggers>
        </Style>
    </DataGridTextColumn.CellStyle>
</DataGridTextColumn>

Answer 3

There is a property on DataGridCell.IsReadOnly that you might think you can bind to,
e.g. using XAML like this:

<!-- Won't work -->
<DataGrid Name="myDataGrid" ItemsSource="{Binding MyItems}">
    <DataGrid.Resources>
        <Style TargetType="DataGridCell">
            <Setter Property="IsReadOnly" Value="{Binding MyIsReadOnly}" />
        </Style>
    </DataGrid.Resources>
    <!-- Column definitions... -->
</DataGrid>

Unfortunantly this won't work because this property is not writable.
Next you might attempt to intercept and stop mouse events, but this won't prevent the user from entering edit mode using the F2 key.

The way I sloved this was by listening for the PreviewExecutedEvent on the DataGrid and then conditionally flagging it as handled.
E.g. by adding code similar to this to the constructor of my Window or UserControl (or another more suitable place):

myDataGrid.AddHandler(CommandManager.PreviewExecutedEvent,
    (ExecutedRoutedEventHandler)((sender, args) =>
{
    if (args.Command == DataGrid.BeginEditCommand)
    {
        DataGrid dataGrid = (DataGrid) sender;
        DependencyObject focusScope = FocusManager.GetFocusScope(dataGrid);
        FrameworkElement focusedElement = (FrameworkElement) FocusManager.GetFocusedElement(focusScope);
        MyRowItemModel model = (MyRowItemModel) focusedElement.DataContext;
        if (model.MyIsReadOnly)
        {
            args.Handled = true;
        }
    }
}));

By doing it like this the cells are still focusable and selectable.
But the user will not be able to enter edit mode unless your model items allow it for the given row.
And you will not suffer the performance costs or complexities by using the DataGridTemplateColumn.

Answer 4

I've solved this problem in my application by setting the underlying object in the cell (eg. CheckBox) - IsHitTestVisible = false; Focusable = false;

var cb = this.dataGrid.Columns[1].GetCellContent(row) as CheckBox;
cb.IsHitTestVisible = false;
cb.Focusable = false;

"row" is a DataGridRow. IsHitTestVisible=false, means that you cant click/select/manipulate the underlying object via mouse, but you can still select the DataGridCell. Focusable=false, means that you can't select/manipulate the underlying object with the keyboard. This gives the illusion of a ReadOnly cell, but you can still select the cell and I'm sure if the DataGrid is set up to SelectionMode=FullRow then clicking the "read only" cell will select the entire row.

Answer 5

My solution is to use binding to the DataGridTemplateColumn with converter.

<UserControl.Resources>
    <c:isReadOnlyConverter x:Key="isRead"/>
</UserControl.Resources>

   <DataGridTemplateColumn x:Name="exampleTemplate" Header="example:" Width="120" IsReadOnly="True">
                <DataGridTemplateColumn.CellTemplate>
                    <DataTemplate>
                            <CheckBox x:Name="exampleCheckBox" VerticalAlignment="Center" IsEnabled="{Binding ElementName=exmpleTemplate, Path=IsReadOnly, Converter={StaticResource isRead}}"/>
                    </DataTemplate>
                </DataGridTemplateColumn.CellTemplate>
            </DataGridTemplateColumn>

and the converter:

class isReadOnlyConverter : IValueConverter
{
    public object Convert(object value, Type targetType, object parameter, System.Globalization.CultureInfo culture)
    {
        try
        {
            return !(bool)value;
        }
        catch (Exception)
        {
            return false;
        }
    }

Answer 6

Based on @sohum comment, here you can use simplified version of the response marked as answer.

dataGrid.BeginningEdit += DataGrid_BeginningEdit;

(...)

private static void DataGrid_BeginningEdit(object sender, DataGridBeginningEditEventArgs e)
{
    //Actual content of the DataGridCell
    FrameworkElement content = e.Column.GetCellContent(e.Row);
    MyObject myObject = (MyObject)content.DataContext;

    if (!myObject.CanEdit)
    {
        e.Cancel = true;
    }
}

You can use it later as Attached Property Behaviour.

Answer 7

One way of getting selectable, read-only text cells for DataGrid is to use template and style like this:

<DataGrid>
<DataGrid.CellStyle>
    <Style TargetType="{x:Type DataGridCell}">                                        
        <Setter Property="BorderThickness" Value="0" />
        <Setter Property="Template">
            <Setter.Value>
                <ControlTemplate TargetType="{x:Type DataGridCell}">
                    <Border Padding="0" BorderBrush="{TemplateBinding BorderBrush}" BorderThickness="{TemplateBinding BorderThickness}" Background="{TemplateBinding Background}" SnapsToDevicePixels="True">
                         <ContentPresenter SnapsToDevicePixels="{TemplateBinding SnapsToDevicePixels}"/>
                        <TextBox BorderThickness="0" MouseDoubleClick="DataGrid_TextBox_MouseDoubleClick" IsReadOnly="True" Padding="5" Text="{Binding RelativeSource={RelativeSource TemplatedParent}, Path=Content.Text}"/>
                    </Border>
                </ControlTemplate>
            </Setter.Value>
        </Setter>
    </Style>
</DataGrid.CellStyle>

And for CS backend:

private void DataGrid_TextBox_MouseDoubleClick(object sender, MouseButtonEventArgs e)
    {
        (sender as TextBox).SelectAll();
    }

Answer 8

This is a bit late but, I was looking into this as well, these solutions work well but I needed something a little different, I did the following and it works exactly like I wanted and what the question is looking for.

I essentially I wanted to be able to enter edit mode for the cell and have all that other templates and command logic the same while not being able to edit the cell.

The solution for all this is to set the TextBox.IsReadOnly property to true in the DataGridCell Style and to handle the initial keydown event

<Style TargetType="DataGridCell">
    <Setter Property="TextBox.IsReadOnly" Value="True"/>
    <EventSetter Event="PreviewKeyDown" Handler="cell_PreviewKeyDown"/>
</Style>

and the following code behind to stop the initial edit

protected void cell_PreviewKeyDown(object sender, KeyEventArgs e)
{
    DataGridCell cell = sender as DataGridCell;
    if (cell.IsEditing == false && 
        ((Keyboard.Modifiers & ModifierKeys.Control) != ModifierKeys.Control)) //So that Ctrl+C keeps working
    {
        cell.IsEditing = true;
        e.Handled = true;
    }
}

Hopefully this is helpful.

Answer 9

In my case I was using DataGridTextColumn. I set the IsEnabled property on ContentPresenter in Style as follows and it works fine -

     <DataGrid ItemsSource="{Binding Items}" AutoGenerateColumns="False">
        <DataGrid.Resources>
            <Style TargetType="{x:Type DataGridCell}">
                <Setter Property="Template">
                    <Setter.Value>
                        <ControlTemplate TargetType="{x:Type DataGridCell}">
                            <Grid Background="{TemplateBinding Background}" >
                                <ContentPresenter IsEnabled="{Binding Path=IsEditable}"/>
                            </Grid>
                        </ControlTemplate>
                    </Setter.Value>
                </Setter>
            </Style>
        </DataGrid.Resources>
        <DataGridTextColumn Header="A" 
                            Binding="{Binding Path=A}"/>
    </DataGrid>

Answer 10

You can do this with a simpler data template.

<DataGrid.Resources>
    <DataTemplate x:Key="MyTemplate" DataType="MyRowDataType">
        <TextBox Text="{Binding Value}" IsReadOnly="{Binding IsReadOnly}" />
    </DataTemplate>
</DataGrid.Resources>

...

<DataGridTemplateColumn CellTemplate="{StaticResource MyTemplate}" />