Develop Reference

Deselect selected item in wpf tree view (MVVM)

I am using a WPF treeview, when i click on a node\item once it gets selected. When the user clicks on the selected node the second time i want this node\item to get deselected i.e. i should be able to get the event. IsSelected is not called if i click on the selected node\item that is already selected. How do i get it to work?
<TreeView Grid.Column="0" Grid.Row="1" ItemsSource="{Binding source}" Name="mytreeview">
<TreeView.ItemContainerStyle>
<Style TargetType="{x:Type TreeViewItem}">
<Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
<Setter Property="FontWeight" Value="Normal" />
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="FontWeight" Value="Bold" />
</Trigger>
</Style.Triggers>
</Style>
</TreeView.ItemContainerStyle>
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Children}">
<TextBlock Text="{Binding displaytext}"/>
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
and in my view model i have
public bool IsSelected
{
get
{
return _isSelected;
}
set
{
if (value != _isSelected)
{
_isSelected = value;
if (_isSelected)
{
//my logic
}
this.OnPropertyChanged("IsSelected");
}
}
}

if (value != _isSelected)
Assuming that the UI is even trying to set something, that line is blocking your toggle logic. Something like this should fix at least that part.
set
{
if (value != _isSelected)
{
_isSelected = value;
this.OnPropertyChanged("IsSelected");
}
else if(_isSelected)
{
IsSelected = false;
}
}
Otherwise the UI is checking the selection before setting the value and you'll need to handle it through some other user interaction like handling deselection on click.

I know this is a bit late but I've recently had the same requirement (i.e. unselecting a selected TreeViewItem on the second click) and I solved it by declaring an event handler for the 'MouseLeftButtonUp' event in a 'Style' entry for the ItemContainerStyle of the TreeView as follows:
<TreeView.ItemContainerStyle>
<Style TargetType="{x:Type TreeViewItem}">
<EventSetter Event="MouseLeftButtonUp" Handler="TreeViewItem_MouseLeftButtonUp"/>
</Style>
</TreeView.ItemContainerStyle>
The event handler in the code behind was as follows:
private TreeViewItem prevTVI;
private void TreeViewItem_MouseLeftButtonUp(object sender, MouseButtonEventArgs e)
{
TreeViewItem tvi = (TreeViewItem)sender;
if (tvi == this.prevTVI)
{
this.prevTVI = null;
if (tvi.IsSelected)
tvi.IsSelected = false;
}
else
this.prevTVI = tvi;
e.Handled = true;
}
Now, I would like to ask if anyone thinks this approach breaks the MVVM pattern? I personally don't think so as the event handler is only concerned with the View and its objects not anything else but I would like to hear what others have to say, especially if someone has an alternative.

The IsSelected property is only changed when you select a new item. Clicking on the same item twice will normally have no effect. You would need to register the MouseDown event on the TreeView, and then force the item to be deselected in the code-behind.

Using ICommand and InputBindings consistently in DataGrid

I'm trying to create a DataGrid having the following features:
Readonly Datagrid, but provide editing capabilities through double click and separate edit form (double click on specific row)
ContextMenu which calls new/edit/delete form (right click on whole DataGrid)
Delete key which calls delete form (on specific selected row)
I thought it would be a good idea to use ICommand, so I created a DataGrid like this:
public class MyDataGrid : DataGrid {
public static readonly RoutedCommand NewEntry = new RoutedCommand();
public static readonly RoutedCommand EditEntry = new RoutedCommand();
public static readonly RoutedCommand DeleteEntry = new RoutedCommand();
public MyDataGrid() {
CommandBindings.Add(new CommandBinding(NewEntry, ..., ...));
CommandBindings.Add(new CommandBinding(EditEntry, ..., ...));
CommandBindings.Add(new CommandBinding(DeleteEntry, ..., ...));
InputBindings.Add(new InputBinding(DeleteCommand, new KeyGesture(Key.Delete)));
InputBindings.Add(new MouseBinding(EditEntry, new MouseGesture(MouseAction.LeftDoubleClick)));
// ContextMenu..working fine
}
}
I then realized, double-clicking a row isn't working, so I added this:
LoadingRow += (s, e) =>
e.Row.InputBindings.Add(new MouseBinding(EditEntry,
new MouseGesture(MouseAction.LeftDoubleClick)));
And of course the delete key isn't working either, I added this:
PreviewKeyDown += (s, e) => { if(e.Key == Key.Delete) { ... } };
Why do I have to do that? Isn't the whole point of having Commands to prevent this kind of hacking around with events? Do I miss something?
In my simple and perfect world, I want to decide in the CanExecute method whether it is appropriate to handle the command, and not subscribe to tons of different event handlers..

Usually I attach the command to the DataGridCell using a Style
Here's an example using a custom AttachedCommandBehavior
<Style TargetType="{x:Type DataGridCell}">
<Setter Property="my:CommandBehavior.Command" Value="{Binding RelativeSource={RelativeSource AncestorType={x:Type local:MyView}}, Path=DataContext.ShowPopupCommand}" />
<Setter Property="my:CommandBehavior.CommandParameter" Value="{Binding RelativeSource={RelativeSource AncestorType={x:Type DataGridRow}}, Path=DataContext}" />
<Setter Property="my:CommandBehavior.Event" Value="MouseDoubleClick" />
</Style>
I can't remember why I attached it to the Cell instead of the Row, but I'm sure there was a reason. You could try attaching the event to the Row instead and see what happens.

Single click edit in WPF DataGrid

I want the user to be able to put the cell into editing mode and highlight the row the cell is contained in with a single click. By default, this is double click.
How do I override or implement this?

Here is how I resolved this issue:
<DataGrid DataGridCell.Selected="DataGridCell_Selected"
ItemsSource="{Binding Source={StaticResource itemView}}">
<DataGrid.Columns>
<DataGridTextColumn Header="Nom" Binding="{Binding Path=Name}"/>
<DataGridTextColumn Header="Age" Binding="{Binding Path=Age}"/>
</DataGrid.Columns>
</DataGrid>
This DataGrid is bound to a CollectionViewSource (Containing dummy Person objects).
The magic happens there : DataGridCell.Selected="DataGridCell_Selected".
I simply hook the Selected Event of the DataGrid cell, and call BeginEdit() on the DataGrid.
Here is the code behind for the event handler :
private void DataGridCell_Selected(object sender, RoutedEventArgs e)
{
// Lookup for the source to be DataGridCell
if (e.OriginalSource.GetType() == typeof(DataGridCell))
{
// Starts the Edit on the row;
DataGrid grd = (DataGrid)sender;
grd.BeginEdit(e);
}
}

The answer from Micael Bergeron was a good start for me to find a solution thats working for me. To allow single-click editing also for Cells in the same row thats already in edit mode i had to adjust it a bit. Using SelectionUnit Cell was no option for me.
Instead of using the DataGridCell.Selected Event which is only fired for the first time a row's cell is clicked, i used the DataGridCell.GotFocus Event.
<DataGrid DataGridCell.GotFocus="DataGrid_CellGotFocus" />
If you do so you will have always the correct cell focused and in edit mode, but no control in the cell will be focused, this i solved like this
private void DataGrid_CellGotFocus(object sender, RoutedEventArgs e)
{
// Lookup for the source to be DataGridCell
if (e.OriginalSource.GetType() == typeof(DataGridCell))
{
// Starts the Edit on the row;
DataGrid grd = (DataGrid)sender;
grd.BeginEdit(e);
Control control = GetFirstChildByType<Control>(e.OriginalSource as DataGridCell);
if (control != null)
{
control.Focus();
}
}
}
private T GetFirstChildByType<T>(DependencyObject prop) where T : DependencyObject
{
for (int i = 0; i < VisualTreeHelper.GetChildrenCount(prop); i++)
{
DependencyObject child = VisualTreeHelper.GetChild((prop), i) as DependencyObject;
if (child == null)
continue;
T castedProp = child as T;
if (castedProp != null)
return castedProp;
castedProp = GetFirstChildByType<T>(child);
if (castedProp != null)
return castedProp;
}
return null;
}

From: http://wpf.codeplex.com/wikipage?title=Single-Click%20Editing
XAML:
<!-- SINGLE CLICK EDITING -->
<Style TargetType="{x:Type dg:DataGridCell}">
<EventSetter Event="PreviewMouseLeftButtonDown" Handler="DataGridCell_PreviewMouseLeftButtonDown"></EventSetter>
</Style>
CODE-BEHIND:
//
// SINGLE CLICK EDITING
//
private void DataGridCell_PreviewMouseLeftButtonDown(object sender, MouseButtonEventArgs e)
{
DataGridCell cell = sender as DataGridCell;
if (cell != null && !cell.IsEditing && !cell.IsReadOnly)
{
if (!cell.IsFocused)
{
cell.Focus();
}
DataGrid dataGrid = FindVisualParent<DataGrid>(cell);
if (dataGrid != null)
{
if (dataGrid.SelectionUnit != DataGridSelectionUnit.FullRow)
{
if (!cell.IsSelected)
cell.IsSelected = true;
}
else
{
DataGridRow row = FindVisualParent<DataGridRow>(cell);
if (row != null && !row.IsSelected)
{
row.IsSelected = true;
}
}
}
}
}
static T FindVisualParent<T>(UIElement element) where T : UIElement
{
UIElement parent = element;
while (parent != null)
{
T correctlyTyped = parent as T;
if (correctlyTyped != null)
{
return correctlyTyped;
}
parent = VisualTreeHelper.GetParent(parent) as UIElement;
}
return null;
}

The solution from http://wpf.codeplex.com/wikipage?title=Single-Click%20Editing worked great for me, but I enabled it for every DataGrid using a Style defined in a ResourceDictionary. To use handlers in resource dictionaries you need to add a code-behind file to it. Here's how you do it:
This is a DataGridStyles.xaml Resource Dictionary:
<ResourceDictionary x:Class="YourNamespace.DataGridStyles"
x:ClassModifier="public"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
<Style TargetType="DataGrid">
<!-- Your DataGrid style definition goes here -->
<!-- Cell style -->
<Setter Property="CellStyle">
<Setter.Value>
<Style TargetType="DataGridCell">
<!-- Your DataGrid Cell style definition goes here -->
<!-- Single Click Editing -->
<EventSetter Event="PreviewMouseLeftButtonDown"
Handler="DataGridCell_PreviewMouseLeftButtonDown" />
</Style>
</Setter.Value>
</Setter>
</Style>
</ResourceDictionary>
Note the x:Class attribute in the root element.
Create a class file. In this example it'd be DataGridStyles.xaml.cs. Put this code inside:
using System.Windows.Controls;
using System.Windows;
using System.Windows.Input;
namespace YourNamespace
{
partial class DataGridStyles : ResourceDictionary
{
public DataGridStyles()
{
InitializeComponent();
}
// The code from the myermian's answer goes here.
}

I solved it by adding a trigger that sets IsEditing property of the DataGridCell to True when the mouse is over it. It solved most of my problems. It works with comboboxes too.
<Style TargetType="DataGridCell">
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="IsEditing" Value="True" />
</Trigger>
</Style.Triggers>
</Style>

i prefer this way based on Dušan Knežević suggestion. you click an that's it ))
<DataGrid.Resources>
<Style TargetType="DataGridCell" BasedOn="{StaticResource {x:Type DataGridCell}}">
<Style.Triggers>
<MultiTrigger>
<MultiTrigger.Conditions>
<Condition Property="IsMouseOver"
Value="True" />
<Condition Property="IsReadOnly"
Value="False" />
</MultiTrigger.Conditions>
<MultiTrigger.Setters>
<Setter Property="IsEditing"
Value="True" />
</MultiTrigger.Setters>
</MultiTrigger>
</Style.Triggers>
</Style>
</DataGrid.Resources>

I looking for editing cell on single click in MVVM and this is an other way to do it.
Adding behavior in xaml
<UserControl xmlns:i="http://schemas.microsoft.com/expression/2010/interactivity"
xmlns:myBehavior="clr-namespace:My.Namespace.To.Behavior">
<DataGrid>
<i:Interaction.Behaviors>
<myBehavior:EditCellOnSingleClickBehavior/>
</i:Interaction.Behaviors>
</DataGrid>
</UserControl>
The EditCellOnSingleClickBehavior class extend System.Windows.Interactivity.Behavior;
public class EditCellOnSingleClick : Behavior<DataGrid>
{
protected override void OnAttached()
{
base.OnAttached();
this.AssociatedObject.LoadingRow += this.OnLoadingRow;
this.AssociatedObject.UnloadingRow += this.OnUnloading;
}
protected override void OnDetaching()
{
base.OnDetaching();
this.AssociatedObject.LoadingRow -= this.OnLoadingRow;
this.AssociatedObject.UnloadingRow -= this.OnUnloading;
}
private void OnLoadingRow(object sender, DataGridRowEventArgs e)
{
e.Row.GotFocus += this.OnGotFocus;
}
private void OnUnloading(object sender, DataGridRowEventArgs e)
{
e.Row.GotFocus -= this.OnGotFocus;
}
private void OnGotFocus(object sender, RoutedEventArgs e)
{
this.AssociatedObject.BeginEdit(e);
}
}
Voila !

I slightly edit solution from Dušan Knežević
<DataGrid.Resources>
<Style x:Key="ddlStyle" TargetType="DataGridCell">
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="IsEditing" Value="True" />
</Trigger>
</Style.Triggers>
</Style>
</DataGrid.Resources>
and apply the style to my desire column
<DataGridComboBoxColumn CellStyle="{StaticResource ddlStyle}">

There are two issues with user2134678's answer. One is very minor and has no functional effect. The other is fairly significant.
The first issueis that the GotFocus is actually being called against the DataGrid, not the DataGridCell in practice. The DataGridCell qualifier in the XAML is redundant.
The main problem I found with the answer is that the Enter key behavior is broken. Enter should move you to the next cell below the current cell in normal DataGrid behavior. However, what actually happens behind the scenes is GotFocus event will be called twice. Once upon the current cell losing focus, and once upon the new cell gaining focus. But as long as BeginEdit is called on that first cell, the next cell will never be activated. The upshot is that you have one-click editing, but anyone who isn't literally clicking on the grid is going to be inconvenienced, and a user-interface designer should not assume that all users are using mouses. (Keyboard users can sort of get around it by using Tab, but that still means they're jumping through hoops that they shouldn't need to.)
So the solution to this problem? Handle event KeyDown for the cell and if the Key is the Enter key, set a flag that stops BeginEdit from firing on the first cell. Now the Enter key behaves as it should.
To begin with, add the following Style to your DataGrid:
<DataGrid.Resources>
<Style TargetType="{x:Type DataGridCell}" x:Key="SingleClickEditingCellStyle">
<EventSetter Event="KeyDown" Handler="DataGridCell_KeyDown" />
</Style>
</DataGrid.Resources>
Apply that style to "CellStyle" property the columns for which you want to enable one-click.
Then in the code behind you have the following in your GotFocus handler (note that I'm using VB here because that's what our "one-click data grid requesting" client wanted as the development language):
Private _endEditing As Boolean = False
Private Sub DataGrid_GotFocus(ByVal sender As Object, ByVal e As RoutedEventArgs)
If Me._endEditing Then
Me._endEditing = False
Return
End If
Dim cell = TryCast(e.OriginalSource, DataGridCell)
If cell Is Nothing Then
Return
End If
If cell.IsReadOnly Then
Return
End If
DirectCast(sender, DataGrid).BeginEdit(e)
.
.
.
Then you add your handler for the KeyDown event:
Private Sub DataGridCell_KeyDown(ByVal sender As Object, ByVal e As KeyEventArgs)
If e.Key = Key.Enter Then
Me._endEditing = True
End If
End Sub
Now you have a DataGrid that hasn't changed any fundamental behavior of the out-of-the-box implementation and yet supports single-click editing.

Several of these answers inspired me, as well as this blog post, yet each answer left something wanting. I combined what seemed the best parts of them and came up with this fairly elegant solution that seems to get the user experience exactly right.
This uses some C# 9 syntax, which works fine everywhere though you may need to set this in your project file:
<LangVersion>9</LangVersion>
First, we get down from 3 clicks to 2 with this:
Add this class to your project:
public static class WpfHelpers
{
internal static void DataGridPreviewMouseLeftButtonDownEvent(object sender, RoutedEventArgs e)
{
// The original source for this was inspired by https://softwaremechanik.wordpress.com/2013/10/02/how-to-make-all-wpf-datagrid-cells-have-a-single-click-to-edit/
DataGridCell? cell = e is MouseButtonEventArgs { OriginalSource: UIElement clickTarget } ? FindVisualParent<DataGridCell>(clickTarget) : null;
if (cell is { IsEditing: false, IsReadOnly: false })
{
if (!cell.IsFocused)
{
cell.Focus();
}
if (FindVisualParent<DataGrid>(cell) is DataGrid dataGrid)
{
if (dataGrid.SelectionUnit != DataGridSelectionUnit.FullRow)
{
if (!cell.IsSelected)
{
cell.IsSelected = true;
}
}
else
{
if (FindVisualParent<DataGridRow>(cell) is DataGridRow { IsSelected: false } row)
{
row.IsSelected = true;
}
}
}
}
}
internal static T? GetFirstChildByType<T>(DependencyObject prop)
where T : DependencyObject
{
int count = VisualTreeHelper.GetChildrenCount(prop);
for (int i = 0; i < count; i++)
{
if (VisualTreeHelper.GetChild(prop, i) is DependencyObject child)
{
T? typedChild = child as T ?? GetFirstChildByType<T>(child);
if (typedChild is object)
{
return typedChild;
}
}
}
return null;
}
private static T? FindVisualParent<T>(UIElement element)
where T : UIElement
{
UIElement? parent = element;
while (parent is object)
{
if (parent is T correctlyTyped)
{
return correctlyTyped;
}
parent = VisualTreeHelper.GetParent(parent) as UIElement;
}
return null;
}
}
Add this to your App.xaml.cs file:
protected override void OnStartup(StartupEventArgs e)
{
base.OnStartup(e);
EventManager.RegisterClassHandler(
typeof(DataGrid),
DataGrid.PreviewMouseLeftButtonDownEvent,
new RoutedEventHandler(WpfHelpers.DataGridPreviewMouseLeftButtonDownEvent));
}
Then we get from 2 to 1 with this:
Add this to the code behind of the page containing the DataGrid:
private void TransactionDataGrid_PreparingCellForEdit(object sender, DataGridPreparingCellForEditEventArgs e)
{
WpfHelpers.GetFirstChildByType<Control>(e.EditingElement)?.Focus();
}
And wire it up (in XAML): PreparingCellForEdit="TransactionDataGrid_PreparingCellForEdit"

I know that I am a bit late to the party but I had the same problem and came up with a different solution:
public class DataGridTextBoxColumn : DataGridBoundColumn
{
public DataGridTextBoxColumn():base()
{
}
protected override FrameworkElement GenerateEditingElement(DataGridCell cell, object dataItem)
{
throw new NotImplementedException("Should not be used.");
}
protected override FrameworkElement GenerateElement(DataGridCell cell, object dataItem)
{
var control = new TextBox();
control.Style = (Style)Application.Current.TryFindResource("textBoxStyle");
control.FontSize = 14;
control.VerticalContentAlignment = VerticalAlignment.Center;
BindingOperations.SetBinding(control, TextBox.TextProperty, Binding);
control.IsReadOnly = IsReadOnly;
return control;
}
}
<DataGrid Grid.Row="1" x:Name="exportData" Margin="15" VerticalAlignment="Stretch" ItemsSource="{Binding CSVExportData}" Style="{StaticResource dataGridStyle}">
<DataGrid.Columns >
<local:DataGridTextBoxColumn Header="Sample ID" Binding="{Binding SampleID}" IsReadOnly="True"></local:DataGridTextBoxColumn>
<local:DataGridTextBoxColumn Header="Analysis Date" Binding="{Binding Date}" IsReadOnly="True"></local:DataGridTextBoxColumn>
<local:DataGridTextBoxColumn Header="Test" Binding="{Binding Test}" IsReadOnly="True"></local:DataGridTextBoxColumn>
<local:DataGridTextBoxColumn Header="Comment" Binding="{Binding Comment}"></local:DataGridTextBoxColumn>
</DataGrid.Columns>
</DataGrid>
As you can see I wrote my own DataGridTextColumn inheriting everything vom the DataGridBoundColumn. By overriding the GenerateElement Method and returning a Textbox control right there the Method for generating the Editing Element never gets called.
In a different project I used this to implement a Datepicker column, so this should work for checkboxes and comboboxes as well.
This does not seem to impact the rest of the datagrids behaviours..At least I haven't noticed any side effects nor have I got any negative feedback so far.

Update
A simple solution if you are fine with that your cell stays a textbox (no distinguishing between edit and non-edit mode). This way single click editing works out of the box. This works with other elements like combobox and buttons as well. Otherwise use the solution below the update.
<DataGridTemplateColumn Header="My Column header">
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBox Text="{Binding MyProperty } />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
Update end
Rant
I tried everything i found here and on google and even tried out creating my own versions. But every answer/solution worked mainly for textbox columns but didnt work with all other elements (checkboxes, comboboxes, buttons columns), or even broke those other element columns or had some other side effects. Thanks microsoft for making datagrid behave that ugly way and force us to create those hacks. Because of that I decided to make a version which can be applied with a style to a textbox column directly without affecting other columns.
Features
No Code behind. MVVM friendly.
It works when clicking on different textbox cells in the same or different rows.
TAB and ENTER keys work.
It doesnt affect other columns.
Sources
I used this solution and #m-y's answer and modified them to be an attached behavior.
http://wpf-tutorial-net.blogspot.com/2016/05/wpf-datagrid-edit-cell-on-single-click.html
How to use it
Add this Style.
The BasedOn is important when you use some fancy styles for your datagrid and you dont wanna lose them.
<Window.Resources>
<Style x:Key="SingleClickEditStyle" TargetType="{x:Type DataGridCell}" BasedOn="{StaticResource {x:Type DataGridCell}}">
<Setter Property="local:DataGridTextBoxSingleClickEditBehavior.Enable" Value="True" />
</Style>
</Window.Resources>
Apply the style with CellStyle to each of your DataGridTextColumns like this:
<DataGrid ItemsSource="{Binding MyData}" AutoGenerateColumns="False">
<DataGrid.Columns>
<DataGridTextColumn Header="My Header" Binding="{Binding Comment}" CellStyle="{StaticResource SingleClickEditStyle}" />
</DataGrid.Columns>
</DataGrid>
And now add this class to the same namespace as your MainViewModel (or a different Namespace. But then you will need to use a other namespace prefix than local). Welcome to the ugly boilerplate code world of attached behaviors.
using System.Windows;
using System.Windows.Controls;
using System.Windows.Media;
namespace YourMainViewModelNameSpace
{
public static class DataGridTextBoxSingleClickEditBehavior
{
public static readonly DependencyProperty EnableProperty = DependencyProperty.RegisterAttached(
"Enable",
typeof(bool),
typeof(DataGridTextBoxSingleClickEditBehavior),
new FrameworkPropertyMetadata(false, OnEnableChanged));
public static bool GetEnable(FrameworkElement frameworkElement)
{
return (bool) frameworkElement.GetValue(EnableProperty);
}
public static void SetEnable(FrameworkElement frameworkElement, bool value)
{
frameworkElement.SetValue(EnableProperty, value);
}
private static void OnEnableChanged(DependencyObject d, DependencyPropertyChangedEventArgs e)
{
if (d is DataGridCell dataGridCell)
dataGridCell.PreviewMouseLeftButtonDown += DataGridCell_PreviewMouseLeftButtonDown;
}
private static void DataGridCell_PreviewMouseLeftButtonDown(object sender, System.Windows.Input.MouseButtonEventArgs e)
{
EditCell(sender as DataGridCell, e);
}
private static void EditCell(DataGridCell dataGridCell, RoutedEventArgs e)
{
if (dataGridCell == null || dataGridCell.IsEditing || dataGridCell.IsReadOnly)
return;
if (dataGridCell.IsFocused == false)
dataGridCell.Focus();
var dataGrid = FindVisualParent<DataGrid>(dataGridCell);
dataGrid?.BeginEdit(e);
}
private static T FindVisualParent<T>(UIElement element) where T : UIElement
{
var parent = VisualTreeHelper.GetParent(element) as UIElement;
while (parent != null)
{
if (parent is T parentWithCorrectType)
return parentWithCorrectType;
parent = VisualTreeHelper.GetParent(parent) as UIElement;
}
return null;
}
}
}

<DataGridComboBoxColumn.CellStyle>
<Style TargetType="DataGridCell">
<Setter Property="cal:Message.Attach"
Value="[Event MouseLeftButtonUp] = [Action ReachThisMethod($source)]"/>
</Style>
</DataGridComboBoxColumn.CellStyle>
public void ReachThisMethod(object sender)
{
((System.Windows.Controls.DataGridCell)(sender)).IsEditing = true;
}

WPF DataGrid SelectedItems - keeping multiple selected while left clicking

is there a way to mimic the behavior of ctrl+click which keeps previously selected rows selected and just adds more selected items?
by default, when clicking on each row, all previously selected rows get de-selected.
one way to achieve this, would be to override SelectionChanged event, and re-select removed rows.
void TestGrid_SelectionChanged(object sender, SelectionChangedEventArgs e) {
foreach (var i in e.RemovedItems)
TestGrid.SelectedItems.Add(i);
}
This is not ideal however, because in some situations i would want to de-select rows (such as when clicking a toggle button in one of the columns).

This is not pretty, but it works if you can live with selecting multiple rows by dragging not working.
private void dataGrid_PreviewMouseDown(object sender, MouseButtonEventArgs e)
{
var dep = (DependencyObject)e.OriginalSource;
// iteratively traverse the visual tree
while ((dep != null) &&
!(dep is DataGridRow))
{
dep = VisualTreeHelper.GetParent(dep);
}
if (dep == null)
return;
if (dep is DataGridRow)
{
var row = dep as DataGridRow;
row.IsSelected = !row.IsSelected;
e.Handled = true;
}
}

Set the SelectionMode to DataGridSelectionMode.Extended

here's a solution that worked for me.
i removed all properties that set details visiblity (to keep everything at default)
than added the following style
<Style x:Key="VisibilityStyle" TargetType="{x:Type DataGridRow}">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=Visible}" Value="False">
<Setter Property="DetailsVisibility" Value="Collapsed" />
</DataTrigger>
<DataTrigger Binding="{Binding Path=Visible}" Value="True">
<Setter Property="DetailsVisibility" Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
assigned this resource to RowStyle
in my underlying data object, i added Visible property, and Implemented INotifyPropertyChanged interface.
now whenever i want to show/hide details, i simply manipulate the Visible property on my underlying object. this can happen from column button handler, to anywhere else in my code. works great

Determining which ListViewItem was clicked on in a ListView when executing a ContextMenu MenuItem

I'm trying to use the context menu in a listview to run some code that requires data from which item it originated from.
I initially just did this:
XAML:
<ListView x:Name="lvResources" ScrollViewer.VerticalScrollBarVisibility="Visible">
<ListView.Resources>
<ContextMenu x:Key="resourceContextMenu">
<MenuItem Header="Get Metadata" Name="cmMetadata" Click="cmMetadata_Click" />
</ContextMenu>
</ListView.Resources>
<ListView.ItemContainerStyle>
<Style TargetType="{x:Type ListViewItem}">
<Setter Property="ContextMenu" Value="{StaticResource resourceContextMenu}" />
</Style>
</ListView.ItemContainerStyle>
...
C#:
private void cmMetadata_Click(object sender, RoutedEventArgs e)
{
// code that needs item data here
}
But I found that the originating listview item was not accessible that way.
I've read some tactics about how to get around this, like intercepting the MouseDown event and setting a private field to the listviewitem that was clicked, but that doesn't sit well with me as it seems a bit hacky to pass data around that way. And WPF is supposed to be easy, right? :) I've read this SO question and this MSDN forum question, but I'm still not sure how to really do this, as neither of those articles seem to work in my case. Is there a better way to pass the item that was clicked on through to the context menu?
Thanks!

Similar to Charlie's answer, but shouldn't require XAML changes.
private void cmMetadata_Click(object sender, RoutedEventArgs e)
{
MenuItem menu = sender as MenuItem;
ListViewItem lvi = lvResources.ItemContainerGenerator.ContainerFromItem(menu.DataContext) as ListViewItem;
}

Well in the cmMetadata_Click handler, you can just query the lvResources.SelectedItem property, since lvResources will be accessible from the code-behind file that the click handler is located in. It's not elegant, but it will work.
If you want to be a little more elegant, you could change where you set up your ContextMenu. For example, you could try something like this:
<ListView x:Name="lvResources" ScrollViewer.VerticalScrollBarVisibility="Visible">
<ListView.Style>
<Style TargetType="ListView">
<Setter Property="ItemContainerStyle">
<Setter.Value>
<Style TargetType="{x:Type ListViewItem}">
<Setter Property="Template">
<Setter.Value>
<ControlTemplate TargetType="{x:Type ListViewItem}">
<TextBlock Text="{TemplateBinding Content}">
<TextBlock.ContextMenu>
<ContextMenu>
<MenuItem Header="Get Metadata" Name="cmMetadata" Click="cmMetadata_Click"
DataContext="{Binding RelativeSource={RelativeSource TemplatedParent}}"/>
</ContextMenu>
</TextBlock.ContextMenu>
</TextBlock>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</Setter.Value>
</Setter>
</Style>
</ListView.Style>
<ListViewItem>One Item</ListViewItem>
<ListViewItem>Another item</ListViewItem>
</ListView>
What this does is plug in a template for your ListViewItem, and then you can use the handy TemplatedParent shortcut to assign the ListViewItem to the DataContext of your menu item.
Now your code-behind looks like this:
private void cmMetadata_Click(object sender, RoutedEventArgs e)
{
MenuItem menu = sender as MenuItem;
ListViewItem item = menu.DataContext as ListViewItem;
}
Obviously the downside is you will now need to complete the template for a ListViewItem, but I'm sure you can find one that will suit your needs pretty quickly.

So I decided to try and implement a command solution. I'm pretty pleased with how it's working now.
First, created my command:
public static class CustomCommands
{
public static RoutedCommand DisplayMetadata = new RoutedCommand();
}
Next in my custom listview control, I added a new command binding to the constructor:
public SortableListView()
{
CommandBindings.Add(new CommandBinding(CustomCommands.DisplayMetadata, DisplayMetadataExecuted, DisplayMetadataCanExecute));
}
And also there, added the event handlers:
public void DisplayMetadataExecuted(object sender, ExecutedRoutedEventArgs e)
{
var nbSelectedItem = (MyItem)e.Parameter;
// do stuff with selected item
}
public void DisplayMetadataCanExecute(object sender, CanExecuteRoutedEventArgs e)
{
e.CanExecute = true;
e.Handled = true;
}
I was already using a style selector to dynamically assign styles to the listview items, so instead of doing this in the xaml, I have to set the binding in the codebehind. You could do it in the xaml as well though:
public override Style SelectStyle(object item, DependencyObject container)
{
ItemsControl ic = ItemsControl.ItemsControlFromItemContainer(container);
MyItem selectedItem = (MyItem)item;
Style s = new Style();
var listMenuItems = new List<MenuItem>();
var mi = new MenuItem();
mi.Header= "Get Metadata";
mi.Name= "cmMetadata";
mi.Command = CustomCommands.DisplayMetadata;
mi.CommandParameter = selectedItem;
listMenuItems.Add(mi);
ContextMenu cm = new ContextMenu();
cm.ItemsSource = listMenuItems;
// Global styles
s.Setters.Add(new Setter(Control.ContextMenuProperty, cm));
// other style selection code
return s;
}
I like the feel of this solution much better than attempting to set a field on mouse click and try to access what was clicked that way.