I have an issue with my datagrid when trying to get a value of a cell. Everything working fine until I'm reaching rows #20. I'm getting a null exception. Is it a limit of datagrid rows in iteration? Because in the visual, I can see all the rows.
I didn't have issue in the past with Datagrid but they were not any radiobutton or checkbox column, perhaps an issue with their rendering?
Here's my code:
XAML
<DataGrid x:Name="datagrid_wafer_300" Margin="5" HeadersVisibility="Column" GridLinesVisibility="None">
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding ID}" Header="ID" Width="140" IsReadOnly="True" Visibility="Hidden">
<DataGridTextColumn.HeaderStyle>
<Style TargetType="{x:Type DataGridColumnHeader}">
<Setter Property="HorizontalAlignment" Value="Stretch"/>
<Setter Property="HorizontalContentAlignment" Value="Center"/>
<Setter Property="FontWeight" Value="Bold" />
</Style>
</DataGridTextColumn.HeaderStyle>
<DataGridTextColumn.ElementStyle>
<Style>
<Setter Property="TextBlock.TextWrapping" Value="Wrap"/>
<Setter Property="TextBlock.TextAlignment" Value="Center"/>
<Setter Property="TextBlock.Margin" Value="10,0"/>
<Setter Property="TextBlock.VerticalAlignment" Value="Center"/>
</Style>
</DataGridTextColumn.ElementStyle>
</DataGridTextColumn>
<DataGridTemplateColumn x:Name="column_check_300" Width="10" IsReadOnly="True">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<RadioButton HorizontalAlignment="Center" VerticalAlignment="Center" GroupName="{Binding Part_Number}" IsChecked="{Binding IsIncluded}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
<DataGridTextColumn Binding="{Binding Part_Number}" Header="Part Number" Width="140" IsReadOnly="True">
<DataGridTextColumn.HeaderStyle>
<Style TargetType="{x:Type DataGridColumnHeader}">
<Setter Property="HorizontalAlignment" Value="Stretch"/>
<Setter Property="HorizontalContentAlignment" Value="Center"/>
<Setter Property="FontWeight" Value="Bold" />
</Style>
</DataGridTextColumn.HeaderStyle>
<DataGridTextColumn.ElementStyle>
<Style>
<Setter Property="TextBlock.TextWrapping" Value="Wrap"/>
<Setter Property="TextBlock.TextAlignment" Value="Center"/>
<Setter Property="TextBlock.Margin" Value="10,0"/>
<Setter Property="TextBlock.VerticalAlignment" Value="Center"/>
</Style>
</DataGridTextColumn.ElementStyle>
</DataGridTextColumn>
<DataGridTextColumn Binding="{Binding Description}" Header="Description" Width="*" IsReadOnly="True">
<DataGridTextColumn.HeaderStyle>
<Style TargetType="{x:Type DataGridColumnHeader}">
<Setter Property="HorizontalAlignment" Value="Stretch"/>
<Setter Property="HorizontalContentAlignment" Value="Center"/>
<Setter Property="FontWeight" Value="Bold" />
</Style>
</DataGridTextColumn.HeaderStyle>
<DataGridTextColumn.ElementStyle>
<Style>
<Setter Property="TextBlock.TextWrapping" Value="Wrap"/>
<Setter Property="TextBlock.TextAlignment" Value="Center"/>
<Setter Property="TextBlock.Margin" Value="10,0"/>
<Setter Property="TextBlock.VerticalAlignment" Value="Center"/>
</Style>
</DataGridTextColumn.ElementStyle>
</DataGridTextColumn>
<DataGridTemplateColumn x:Name="column_exclude_300" Header="Exclude?" Width="60" IsReadOnly="True">
<DataGridTemplateColumn.HeaderStyle>
<Style TargetType="{x:Type DataGridColumnHeader}">
<Setter Property="HorizontalAlignment" Value="Stretch"/>
<Setter Property="HorizontalContentAlignment" Value="Center"/>
<Setter Property="VerticalAlignment" Value="Center"/>
<Setter Property="FontWeight" Value="Bold" />
</Style>
</DataGridTemplateColumn.HeaderStyle>
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<RadioButton HorizontalAlignment="Center" VerticalAlignment="Center" GroupName="{Binding Part_Number}" IsChecked="{Binding IsIncluded}"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
</DataGrid.Columns>
</DataGrid>
C# code:
private void Clear_Datagrid()
{
for (int i = 0; i < datagrid_wafer_200.Items.Count; i )
{
var item = datagrid_wafer_200.Items[i];
FrameworkElement elmtTest = datagrid_wafer_200.Columns[1].GetCellContent(item);
var radio = FindVisualChild<RadioButton>(elmtTest);
var wafer = datagrid_wafer_200.Columns[2].GetCellContent(item) as TextBlock;
FrameworkElement elmtTest1 = datagrid_wafer_200.Columns[4].GetCellContent(item);
var exclude = FindVisualChild<RadioButton>(elmtTest1);
radio.IsChecked = false;
exclude.IsChecked = false;
}
for (int i = 0; i < datagrid_wafer_300.Items.Count; i )
{
var item = datagrid_wafer_300.Items[i];
FrameworkElement elmtTest = datagrid_wafer_300.Columns[1].GetCellContent(item);
var radio = FindVisualChild<RadioButton>(elmtTest);
var wafer = datagrid_wafer_300.Columns[2].GetCellContent(item) as TextBlock;
FrameworkElement elmtTest1 = datagrid_wafer_300.Columns[4].GetCellContent(item);
var exclude = FindVisualChild<RadioButton>(elmtTest1);
radio.IsChecked = false;
exclude.IsChecked = false;
}
}
Thank you
CodePudding user response：
Is it a limit of datagrid rows in iteration?
It's called UI virtualization and means that the visual containers for the data items are created on a per-need basis.
It's considered a bad practice to acess the visual elements directly but if you really need to do this for one reason or another you should probably turn off the virtualization:
<DataGrid VirtualizingPanel.IsVirtualizing="False" EnableRowVirtualization="False" ... />
The other option is otherwise to bind the IsChecked property of the RadioButton to a property of your data object and looking at this property instead of the one of the RadioButton.
CodePudding user response：
Your iteration starts from 0 to your list's count. Seems like the list has 19 elements and your loop continues to the 20th element wich is null.
It should be like this:
for (int i = 0; i < datagrid_wafer_200.Items.Count - 1; i )
{
// ...
}
for (int i = 0; i < datagrid_wafer_300.Items.Count - 1; i )
{
// ...
}