WPF: System.ArgumentException => {“'{0}' is not a Visual or Visual3D.”}

问题

when I double-click - or click once when its already focused - below the items in a empty area of the Listbox which is within my DataGridTemplateColumn then I get the above error message.

WHAT do I wrong?

This is my Code:

<DataGridTemplateColumn Width="0.3*" Header="Attachments">
    <DataGridTemplateColumn.CellTemplate>
        <DataTemplate>
            <StackPanel Orientation="Vertical">
                <Button>Add</Button>
                <Button>Delete</Button>
                <ListBox Name="itemListBox" BorderThickness="0" ItemsSource="{Binding Attachments}" >                                   
                    <ListBox.ItemTemplate>
                        <DataTemplate>                                           
                            <StackPanel Orientation="Vertical" Margin="5">                                                
                                <TextBlock Text="{Binding DocumentFilename}" />
                            </StackPanel>                                            
                        </DataTemplate>
                    </ListBox.ItemTemplate>                                     
                </ListBox>
            </StackPanel>
        </DataTemplate>
    </DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>

Regard that image where I click below the "myPhotos.png" item entry:
_{(source: 666kb.com)}

EDIT: this error is also already visible in XAML via tooltip just haven`t seen that error tooltip...

回答1:

That indeed seems to be a bug. I ran your repro project and checked out the call stack when the exception is thrown. It happens in DataGridCell.RemoveBindingExpressions during a call to VisualTreeHelper.IsAncestorOf. The latter method throws an exception when it is passed an object that is not Visual or Visual3D. But DataGridCell is passing it whatever element is the target of the binding. In your case that happens to be a Run which does not derive from Visual.

I was thinking you might be able to work around it by using an IValueConverter to create the FlowDocument and binding RichTextBox.Document so that the binding is being applied to the RichTextBox. But since Document isn't a dependency property, it can't be a target of binding.

So instead what you might want to do is create a UserControl that hosts the RichTextBox control:

<DataGridTemplateColumn.CellTemplate>
    <DataTemplate>
        <Local:HomeworkControl Text="{Binding Homework}" />
    </DataTemplate>
</DataGridTemplateColumn.CellTemplate>

Then in that user control you would take care of building the RichTextBox, document, run, etc. Unfortunately I think this is just a limitation (aka bug) in the DataGrid control.

回答2:

Interestingly this happened to me as well. What Josh said got me thinking. It seems like once you select the cell and select it again it tries to load the CellEditingTemplate which is not specified in my case and yours and it throws the Visual/Visual3d exception.

I got it fixed by specifying IsReadOnly="True" on my DataGridTemplateColumn. I don't use the CellEditingTemplate anyway because I am doing bulk inserts with TextBoxes/DatePicker/Checkboxes etc. loaded in the cell templates.

回答3:

I had the same problem with a Datagrid with a custom column with a Hyperlink with embedded run, with the binding set on the Run's Text property. When the run Text binding was not explicitly set to be BindingMode.OneWay I got this error. Setting it explicitly solved the problem. Note I got the exception when editing ANY columns in the datagrid not just this one.

回答4:

I get this error frequently in Blend, but not at runtime in a DataGrid.

I have found that either compiling the application (in my case in VS) and allowing Blend to reload the DLLs fixes it. Also rearranging the columns seems to trigger it to update itself. Big pain though!

回答5:

I get this same error when editing a column in a data grid. here xaml column:

 <DataGridTextColumn Header="Precio Unit." Binding="{Binding UnitPrice,StringFormat=0.00}" Width="Auto" MinWidth="115" />

But the error occurred in another column; here the xaml:

                        <DataGridTemplateColumn Header="Descripción" MinWidth="600" Width="Auto" IsReadOnly="True" >
                            <DataGridTemplateColumn.CellTemplate >
                                <DataTemplate >
                                    <StackPanel Orientation="Horizontal" HorizontalAlignment="Center" VerticalAlignment="Center">
                                        <TextBlock Text="{Binding FixedName, Converter={StaticResource toUpperConverter}}" Background="Transparent" 
                                                VerticalAlignment="Center" Margin="0"/>
                                        <TextBlock Margin="5,0,0,0" Foreground="#FFCB6A6A" FontWeight="Normal">
                                            <Run Text="( Stock "/>
                                            <Run Text="{Binding Stock}"/>
                                            <Run Text=" )"/>
                                        </TextBlock>
                                    </StackPanel>
                                </DataTemplate>
                            </DataGridTemplateColumn.CellTemplate>
                        </DataGridTemplateColumn>

The error disappears specifying explicitly:

<Run Text = "{Binding Stock, Mode = OneWay}" />

来源：https://stackoverflow.com/questions/2375237/wpf-system-argumentexception-0-is-not-a-visual-or-visual3d

标签

wpf

exception

listbox

datagridtemplatecolumn