I seem to have conflicting requirements. I have a DataGrid that has a checkbox as the first column. The users want the checkbox to be selectable with a single click, not a double click. I was able to make that happen by using a DataGridTemplateColumn and a checkbox like this:
<DataGridTemplateColumn>
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<CheckBox IsChecked="{Binding IsSelected, UpdateSourceTrigger=PropertyChanged}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
The user also a control that allows them to specify a row (there can be hundreds of rows). If they specify a row that isn't in view I want it to scroll into view. I compromised and added an event handler in the code behind for the DataGrid_SelectionChanged event. Originally I was just using the ScrollIntoView command but offscreen rows would get highlighted but the grid did not scroll them into view. I was then able to add a Focus command and the row scrolled into view. So now the event handler looks like this:
private void DataGrid_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
DataGrid dg = (DataGrid)sender;
if (dg.SelectedItem == null) return;
dg.ScrollIntoView(dg.SelectedItem);
dg.SelectedItem.Focus();
}
Now I'm back to the original problem, the row scrolls into view but to check the checkbox on any other row (that you don't move into via the jump to row control) you have to click twice. Anybody know what is causing the rows moved to manually to require double clicks?
Well I got it to work with the following code which was inspired by some tangentially related posts on getting the focus into cells. I have no clue as to why ScrollIntoView doesn't work, working or why performing the last three lines was the one way I could get the row to scroll into view without disabling the checkbox.
private void DataGrid_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
DataGrid dg = (DataGrid)sender;
if (dg.SelectedItem == null) return;
dg.ScrollIntoView(dg.SelectedItem);
DataGridRow dg_row = (DataGridRow)dg.ItemContainerGenerator.ContainerFromItem(dg.SelectedItem);
if (dg_row == null) return;
dg_row.Focus();
}
Related
In my DataGrid I am using DataGridComboBoxColumn as follows. Its SelectionChanged event (defined below) always fires twice - once when I click on an item, and then again when I select the new item from the dropdown. When I click on the item that I want to change the SelectionChanged event fires and shows the old value, and then when I select on a new value it fires again and correctly show the new value. But I want the event to be fired only when I select a new value for the combobox.
Question: What is causing this behavior and how can the issue be fixed?
Remark: Many users online seem to have similar issues posted here but none of them helped resolve my issue - maybe, the context is a bit different here. Moreover, the XAML and the code seem ok as it correctly displays the combobox values along with the correctly combox selected values for each row in the grid. Plus, the SelectionChanged event does correctly show the newly selected value but when it fires the second time. Similar code is shown here.
<DataGridComboBoxColumn Header="StartTime" SelectedItemBinding="{Binding localTime}" ItemsSource="{StaticResource localTimeList}">
<DataGridComboBoxColumn.EditingElementStyle>
<Style TargetType="ComboBox">
<EventSetter Event="SelectionChanged" Handler="MyComboBoxColumn_SelectionChanged"/>
</Style>
</DataGridComboBoxColumn.EditingElementStyle>
</DataGridComboBoxColumn>
The event:
private void MyComboBoxColumn_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
ComboBox comboBox = (ComboBox)sender;
var selectedVal = comboBox.SelectedValue.ToString();
}
What is causing this behavior?
The SelectionChanged event is raised initially when you enter the edit mode and the SelectedItem property is being bound to your source property.
How can the issue be fixed?
The easiest way to handle this is to check whether the ComboBox has been loaded and simply return from the event handler immediately if it hasn't:
private void MyComboBoxColumn_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
ComboBox comboBox = (ComboBox)sender;
if (!comboBox.IsLoaded)
return;
//handle an actual selection here...
}
I display a few thousand rows in a WPF DataGrid, but would like to automatically scroll to a specific row when it is loaded (and later also add a button to scroll to this specific row). Is it possible to achieve it via data binding or from a view model property?
Of course, I've already browsed the Internet, but could not find any corresponding property.. For exemple, SelectedCells only has a get accessor (but I don't think it would have scrolled whatsoever anyway). I don't think that the other properties, such as SelectedItem helps.
Thanks for any insights :-)
There are two options: scroll to a row without selecting it and scroll to a row and select it.
Scroll to row without selecting it
This solution works for any DataGrid.SelectionUnit value (cell or row based selection).
You set the row from a property in your view model, which binds to DataGrid.CurrentItem.
Scrolling must be handled by the DataGrid by handling the DataGrid.CurrentCellChanged event.
View model (must implement INotifyPropertyChanged)
object currentRow = this.DataSource[currentRowIndex];
this.CurrentRow = currentRow;
View.xaml
<DataGrid ItemsSource="{Binding DataSource}"
CurrentItem="{Binding CurrentRow}"
CurrentCellChanged="DataGrid_OnCurrentCellChanged" />
View.xaml.cs
private void DataGrid_OnCurrentCellChanged(object sender, EventArgs eventArgs)
{
var dataGrid = sender as DataGrid;
dataGrid.ScrollIntoView(dataGrid.CurrentItem);
}
Scroll to row by selecting it
This solution works only for DataGrid.SelectionUnit values DataGridSelectionUnit.FullRow or DataGridSelectionUnit.CellOrRowHeader (not cell-only based selection - cell-only solution must completely handle selection and scroll in view).
You set the selected row from a property in your view model, which binds to DataGrid.SelectedItem.
Scrolling must be handled by the DataGrid by handling the DataGrid.SelectionChanged event.
View model (must implement INotifyPropertyChanged)
object selectedRow = this.DataSource[currentRowIndex];
this.SelectedRow = selectedRow;
View.xaml
<DataGrid ItemsSource="{Binding DataSource}"
SelecetedItem="{Binding SelectedRow}"
SelectionChanged="DataGrid_OnCurrentCellChanged" />
View.xaml.cs
private void DataGrid_OnSelectionChanged(object sender, SelectionChangedEventArgs eventArgs)
{
var dataGrid = sender as DataGrid;
dataGrid.ScrollIntoView(dataGrid.SelectedItem);
}
I have a wpf datagrid with SelectionUnit set to "CellOrRowHeader" and SelectionMode set to "Extended".
<DataGrid SelectionUnit="Cell" SelectionMode="Extended" Name="myDataGrid">
CurrentCellChanged="onCurrentCellChanged"
</DataGrid>
Inside the onCurrentCellChanged I tried to change the selection to another cell:
private void onCurrentCellChanged(object sender, EventArgs e)
{
DataGridCell cell = DataGridHelper.GetCell(myDataGrid, 3, 3);
cell.IsSelected = true;
cell.Focus();
}
The GetCell is a helper function. I verified that the cell is not null, and the codes are executed. However, I only see the cell {3,3} is focused (with a black border), but not highlighted (without blue background).
The strange thing is that if I call the same code, but not inside onCurrentCellChanged event callback, the cell {3,3} got highlighted.
Anybody knows the reason ? Many thanks！
Besides "CurrentCellChanged", There is another event "SelectedCellsChanged" that acts differently. After some tests, I figured out that these two events serve different purpose. For example, in some cases, the "CurrentCellChanged" gets called even if the selection is not changed. While that's beyond the scope of this answer...
Back to the topic, I managed to resolve the problem by manipulating the cell selection inside SelectedCellsChanged event call back. BUT there is some trick:
Change the markup:
<DataGrid SelectionUnit="Cell" SelectionMode="Extended" Name="myDataGrid">
SelectedCellsChanged="onSelectedCellsChanged"
</DataGrid>
Here is the handler:
private void onSelectedCellsChanged(object sender, SelectedCellsChangedEventArgs e)
{
// trick: Since the code below change the cell selection, which may
// cause this handler to be called recursively, I need to do some filter
// If myDataGrid.CurrentCell != e.AddedCells.First(), return
// Here we can change cell selection
DataGridCell cell = DataGridHelper.GetCell(myDataGrid, 3, 3);
cell.IsSelected = true;
}
I have bound a datatable to a datagrid in WPF. Now on clicking a row in the grid I need to have a window pop up. But for that, I need to first change a column in the datagrid to be a hyperlink. Any ideas on how to do that?
<DataGrid Name="dgStep3Details" Grid.Column="1" Margin="8,39,7,8" IsReadOnly="True" ItemsSource="{Binding Mode=OneWay, ElementName=step3Window,Path=dsDetails}" />
If I can't change an autogenerated column to hyperlink, is there a way to add a button to each row instead?
Thanks
Nikhil
So, it was really hard to create hyperlink columns to autogenerated datagrid. What I eventually did was this - create buttons to the grid on the fly and then attach a routed event for the same based on the autogenerate event of the datagrid where I shall put my code. I didn't want my code to be hardcoded to the columns and now I'm flexible by changing the datatable on the fly. Here is the code:
private void dgStep3Details_AutoGeneratedColumns(object sender, EventArgs e)
{
DataGrid grid = sender as DataGrid;
if (grid == null)
return;
DataGridTemplateColumn col = new DataGridTemplateColumn();
col.Header = "More Details";
FrameworkElementFactory myButton = new FrameworkElementFactory(typeof(Button), "btnMoreDetails");
myButton.SetValue(Button.ContentProperty, "Details");
myButton.AddHandler(Button.ClickEvent, new RoutedEventHandler(btnMoreDetails_Click));
DataTemplate cellTempl = new DataTemplate();
//myButton.SetValue(Button.CommandParameterProperty, ((System.Data.DataRowView)((dgStep3Details.Items).CurrentItem)).Row.ItemArray[0]);
cellTempl.VisualTree = myButton;
col.CellTemplate = cellTempl;
dgStep3Details.Columns.Add(col);
}
public void btnMoreDetails_Click(object sender, RoutedEventArgs e)
{
//Button scrButton = e.Source as Button;
string currentDetailsKey = ((System.Data.DataRowView)(dgStep3Details.Items[dgStep3Details.SelectedIndex])).Row.ItemArray[0].ToString();
// Pass the details key to the new window
}
I don't think you'll be able to get these advanced UI features out of autogenerated columns. I think you'll either have to decide to program these columns in C# or VB.NET when you retrieve your data and tailor them the way you like, or you'll have to abandon the UI ideas you've mentioned. Autogenerated columns just cannot do that.
However, you could change your approach. Try checking into events like MouseLeftButtonDown, etc. and see if you can simulate the behavior you want by other means.
I need to dynamically set the contents within the template of a DataGrid based on information in an external settings file. That settings file specifies which data fields should display in the DataGrid. The administrator of the application can edit the settings to change the fields to display. I cannot hard-code the fields to display.
I can easily add the columns (DataGridTextColumn's) to the DataGrid at runtime. I set a binding to a field in the item source based on the settings, and that displays fine.
Now I need to display details when the user clicks a row. I set up a RowDetailsTemplate with DataTemplate, and added a Grid (or a StackPanel) inside to format the details. If I add to the markup the TextBlocks with bindings to fields, it displays the details just fine.
But how can I set the content of the Grid/StackPanel in the details template programmatically? The Grid/StackPanel controls are null if I try to reference them by name on startup (e.g., in the page Loaded event). I have tried using the Loaded event on the Grid/StackPanel to add the details. That code runs and appears to add the content to the Grid/StackPanel, but nothing actually appears when I click the row. I'm guessing that the problem is that the template/Grid is already loaded and ignores the changes I'm making.
Here's a sample of the code I'm using in the handler for the Loaded event. Even if I do something as simple as this, the details pane doesn't appear when clicking on the row.
<data:DataGrid.RowDetailsTemplate>
<DataTemplate>
<Border Background="LightBlue" >
<StackPanel x:Name="resultsDetailsPanel"
Orientation="Vertical"
Loaded="resultsDetailsPanel_Loaded">
</StackPanel>
</Border>
</DataTemplate>
</data:DataGrid.RowDetailsTemplate>
private void resultsDetailsPanel_Loaded(object sender, RoutedEventArgs e)
{
if (_resultsGridLoaded)
return;
StackPanel detailsPanel = sender as StackPanel;
TextBlock fieldNameTextBlock = new TextBlock();
fieldNameTextBlock.Text = "TESTING";
detailsPanel.Children.Add(fieldNameTextBlock);
_resultsGridLoaded = true;
}
I actually tried your code and is working. Two things you should check:
Is your _resultsGridLoaded variable initialized as false?
Did you set RowDetailsVisibilityMode="VisibleWhenSelected" on your DataGrid?
UPDATE: For some reason is not working anymore. But I did found two ways you can fix it:
Remove the resultsGridLoaded logic.
If you need that logic, you can add a handler for the SelectionChanged event on the DataGrid, in there you can set the _resultsGridLoaded variable to false so the new StackPanel gets its content added correctly:
And the code behind:
private void resultsPanel_Loaded(object sender, RoutedEventArgs e)
{
if (_resultsGridLoaded)
return;
StackPanel pane = (StackPanel)sender;
TextBlock newChild = new TextBlock()
{
Text = "New text"
};
pane.Children.Add(newChild);
_resultsGridLoaded = true;
}
private void grid_SelectionChanged(object sender, SelectionChangedEventArgs e)
{
_resultsGridLoaded = false;
}
Hope this helps