Is there a way in XAML to determine if the ListBox has data?
I wanna set its IsVisibile property to false if no data.
The ListBox contains a HasItems property you can bind to. So you can just do this:
<BooleanToVisibilityConverter x:Key="BooleanToVisibility" />
...
<ListBox
Visibility="{Binding HasItems,
RelativeSource={RelativeSource Self},
Converter=BooleanToVisibility}" />
Or as a Trigger so you don't need the converter:
<ListBox>
<ListBox.Style>
<Style TargetType="{x:Type ListBox}">
<Setter Property="Visibility" Value="Visible" />
<Style.Triggers>
<DataTrigger
Binding="{Binding HasItems, RelativeSource={RelativeSource Self}}"
Value="False">
<Setter Property="Visibility" Value="Hidden" />
</DataTrigger>
</Style.Triggers>
</Style>
</ListBox.Style>
</ListBox>
I haven't tested the bindings so there might be some typos but you should get the idea.
Do it in a trigger and you won't need a ValueConverter:
<ListBox>
<ListBox.Style>
<Style TargetType="{x:Type ListBox}">
<Style.Triggers>
<DataTrigger
Binding="Items.Count, {Binding RelativeSource={RelativeSource Self}}"
Value="0">
<Setter Property="Visibility" Value="Hidden" />
</DataTrigger>
</Style.Triggers>
</Style>
</ListBox.Style>
</ListBox>
So that shows the ListBox by default, but if Items.Count is ever 0, the ListBox is hidden.
<ListBox.Style>
<Style TargetType="ListBox">
<Setter Property="Visibility" Value="Visible"/>
<Style.Triggers>
<Trigger Property="HasItems" Value="False">
<Setter Property="Visibility" Value="Hidden"/>
</Trigger>
</Style.Triggers>
</Style>
</ListBox.Style>
You can probably make this work using a ValueConverter and normal binding.
Set Visibility to be:
Visibility = "{Binding myListbox.Items.Count, Converter={StaticResource VisibilityConverter}}"
Then set up your converter to return Visibility.Collapsed etc based on the value of the count.
Related
I am in a similar case that this question:
Displaying Content only when ListViewItem is Selected
I have a ComboBox that I only want to show when the ListViewItem that contains it is selected and when the ComboBox is not empty (both conditions must be true). It is very easy to bind visibility to a readonly property that checks if the ItemsSource property in the ViewModel has any items, and with the above link it is also solved how to show it only when its ListViewItem is selected, but I am not able to join both conditions. How can I only show the ComboBox when the item is selected and the combo is not empty?
This Style in the ComboBox does the trick for showing only when is selected:
<ComboBox ItemsSource="{Binding DataContext.ListaPedidosPendientes, RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}" DisplayMemberPath="numero">
<ComboBox.Style>
<Style TargetType="{x:Type ComboBox}">
<Setter Property="Visibility" Value="Collapsed"/>
<Style.Triggers>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor,
AncestorType={x:Type ListBoxItem}},Path=IsSelected}" Value="True">
<Setter Property="Visibility" Value="Visible"/>
</DataTrigger>
</Style.Triggers>
</Style>
</ComboBox.Style>
</ComboBox>
How can I add there the second condition (ListaPedidosPendientes.Count > 0)?
Thank you
You can evaluate the HasItems property of the ComboBox https://learn.microsoft.com/en-us/dotnet/api/system.windows.controls.itemscontrol.hasitems?view=net-5.0
and invert the conditions: Visible by default, collapse when not selected or when no items. Untested Aircode:
<ComboBox ItemsSource="{Binding DataContext.ListaPedidosPendientes, RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}" DisplayMemberPath="numero">
<ComboBox.Style>
<Style TargetType="{x:Type ComboBox}">
<Setter Property="Visibility" Value="Visible"/>
<Style.Triggers>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor,
AncestorType={x:Type ListBoxItem}},Path=IsSelected}" Value="False">
<Setter Property="Visibility" Value="Collapsed"/>
</DataTrigger>
<Trigger Property="HasItems" Value="False">
<Setter Property="Visibility" Value="Collapsed"/>
</Trigger>
</Style.Triggers>
</Style>
</ComboBox.Style>
</ComboBox>
There are two triggers to be set.
And the conditions are opposite.
Since the trigger only checks for equality, so you can compare Items.Count with zero.
But the condition >0 cannot be checked.
<ComboBox ItemsSource="{Binding DataContext.ListaPedidosPendientes, RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl}}" DisplayMemberPath="numero">
<ComboBox.Style>
<Style TargetType="{x:Type ComboBox}">
<Setter Property="Visibility" Value="Visible"/>
<Style.Triggers>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Mode=FindAncestor,
AncestorType={x:Type ListBoxItem}},Path=IsSelected}" Value="False">
<Setter Property="Visibility" Value="Collapsed"/>
</DataTrigger>
<DataTrigger Binding="{Binding RelativeSource={RelativeSource Self}, Path=Items.Count}" Value="0">
<Setter Property="Visibility" Value="Collapsed"/>
</DataTrigger>
</Style.Triggers>
</Style>
</ComboBox.Style>
</ComboBox>
I would like to gray out the text associated to an unchecked row in my application using xaml. I tried the following, but it is getting overwritten:
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<CheckBox Name="cbkSelect"
IsChecked="{Binding Path=IsSelectedForOrder, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
<CheckBox.Style>
<Style TargetType="{x:Type CheckBox}">
<Setter Property="Visibility" Value="Hidden"/>
<Style.Triggers>
<Trigger Property="IsChecked" Value="False">
<Setter Property="Foreground" Value="Gray"/>
</Trigger>
<DataTrigger Binding="{Binding IsMouseOver, RelativeSource={RelativeSource AncestorType={x:Type DataGridRow}}}" Value="True">
<Setter Property="Visibility" Value="Visible"/>
</DataTrigger>
</Style.Triggers>
</Style>
</CheckBox.Style>
</CheckBox>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
As the Foreground color should be applied to all cells of a given row, you can remove the trigger. The trigger inside the CellTemplate will only apply to to the CheckBox that the style is applied to.
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<CheckBox Name="cbkSelect"
IsChecked="{Binding Path=IsSelectedForOrder, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}">
<CheckBox.Style>
<Style TargetType="{x:Type CheckBox}">
<Setter Property="Visibility" Value="Hidden"/>
<Style.Triggers>
<DataTrigger Binding="{Binding IsMouseOver, RelativeSource={RelativeSource AncestorType={x:Type DataGridRow}}}" Value="True">
<Setter Property="Visibility" Value="Visible"/>
</DataTrigger>
</Style.Triggers>
</Style>
</CheckBox.Style>
</CheckBox>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
If you want to apply the foreground color in normal state, but not in selected state, add this RowStyle.
<DataGrid.RowStyle>
<Style TargetType="{x:Type DataGridRow}" BasedOn="{StaticResource {x:Type DataGridRow}}">
<Style.Triggers>
<DataTrigger Binding="{Binding IsSelectedForOrder}" Value="True">
<Setter Property="Foreground" Value="Gray"/>
</DataTrigger>
</Style.Triggers>
</Style>
</DataGrid.RowStyle>
If you want to apply the style in selected state, too, add this CellStyle. In this case a RelativeSource binding is used to access the data context of the row which contains IsSelectedForOrder.
<DataGrid.CellStyle>
<Style TargetType="{x:Type DataGridCell}" BasedOn="{StaticResource {x:Type DataGridCell}}">
<Style.Triggers>
<DataTrigger Binding="{Binding DataContext.IsSelectedForOrder, RelativeSource={RelativeSource AncestorType={x:Type DataGridRow}}}" Value="True">
<Setter Property="Foreground" Value="Gray"/>
</DataTrigger>
</Style.Triggers>
</Style>
</DataGrid.CellStyle>
Does anyone know how to add default content to an empty datagrid or listbox? Such as "No Results Returned" or something along those lines.
You can do something like this, where the ListBox is Hidden and an associated error Grid is displayed instead. The benefit of this approach is that it is a bit more flexible, as you have an entire Grid to use instead of a VisualBrush.
<Grid>
<ListBox x:Name="MyListBox">
<ListBox.Style>
<Setter Property="Visibility" Value="Visible" />
<Style TargetType="ListBox">
<Style.Triggers>
<DataTrigger Binding="{Binding Items.Count, RelativeSource={RelativeSource Self}}" Value="0">
<Setter Property="Visibility" Value="Hidden" />
</DataTrigger>
</Style.Triggers>
</Style>
</ListBox.Style>
</ListBox>
<Grid>
<Grid.Style>
<Style TargetType="Grid">
<Setter Property="Visibility" Value="Hidden" />
<Style.Triggers>
<DataTrigger Binding="{Binding ElementName=MyListBox, Path=Items.Count}" Value="0">
<Setter Property="Visibility" Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
<Grid.Style>
<TextBlock Text="No Results Returned" />
</Grid>
<Grid>
<Style.Triggers>
<DataTrigger Binding="{Binding Items.Count, RelativeSource={RelativeSource Self}}" Value="0">
<Setter Property="CanUserSortColumns" Value="False" />
<Setter Property="Background">
<Setter.Value>
<VisualBrush Stretch="None">
<VisualBrush.Visual>
<TextBlock Text="We did't find any matching records for your group..." FontSize="14" FontWeight="SemiBold" Foreground="LightCoral"/>
</VisualBrush.Visual>
</VisualBrush>
</Setter.Value>
</Setter>
</DataTrigger>
</Style.Triggers>
This is what I have found and was able to to test it. Thanks to anyone who tried to help.
As the title says, I have a hidden border with some controls inside, and I would like to show it when a particular item in a combobox is selected.
I tried the following
<ComboBox Name="cmbRequiredRule" SelectedValuePath="Content"
SelectedValue="{Binding Path=ClientValidation.NarrativeRequiredRule}">
<ComboBoxItem>All</ComboBoxItem>
<ComboBoxItem>Matching</ComboBoxItem>
</ComboBox>
<Border Visibility="Collapsed">
<Border.Resources>
<Style TargetType="{x:Type Border}">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=ClientValidation.NarrativeRequiredRule}" Value="Matching">
<Setter Property="Visibility" Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
</Border.Resources>
....
</Border>
and this property in the view model:
public string NarrativeRequiredRule
{
get...
set...
}
but the trigger doesn't seem to be working
Try setting Visibility=Collapsed in your Style Setters, not as part of the Border Tag. I've had issues in the past where a DataTrigger would not apply when the value was specified as part of the Tag.
<Border>
<Border.Resources>
<Style TargetType="{x:Type Border}">
<Setter Property="Visibility" Value="Collapsed" />
<Style.Triggers>
<DataTrigger Binding="{Binding Path=Test}" Value="Matching">
<Setter Property="Visibility" Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
</Border.Resources>
...
</Border>
Locally assigned value takes precedence over styles. Hence you need to have
<Setter Property="Visibility" Value="Collapsed" />
in Style as #Rachel has pointed out.
Also I tried debugging the binding using a dummy converter and found that the value turned out to be System.Windows.Controls.ComboBoxItem: Matching instead of Matching.
Hence your final style is:
<Style TargetType="{x:Type Border}">
<Setter Property="Visibility" Value="Collapsed" />
<Style.Triggers>
<DataTrigger Binding="{Binding Path=ClientValidation.NarrativeRequiredRule}" Value="System.Windows.Controls.ComboBoxItem: Matching">
<Setter Property="Visibility" Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
could be binding issue. In your example below:
<DataTrigger Binding="{Binding Path=ClientValidation.NarrativeRequiredRule}" Value="Matching">
where is the ClientValidation located ? because if the whole View's DataContext is bound to VM, you will need to include these hierarchies. Check your Output log, it should throw some errors if binding failes
In my application, I have a TextBox that I want to enable/disable based on an enum in my datacontext. The enum has three values (Anyone, Me, Someone) and I want to enable the Textbox when the value "Someone" is set. I am able to hack a solution by setting the value in reverse (see below). However, can someone please explain why the first solution didn't work?
This does not work...
<TextBox Text="{Binding ModifiedUser, UpdateSourceTrigger=PropertyChanged}"
IsEnabled="False">
<TextBox.Style>
<Style TargetType="{x:Type TextBox}">
<Style.Triggers>
<DataTrigger Binding="{Binding ModifiedBy}"
Value="Someone">
<Setter Property="IsEnabled"
Value="True" />
</DataTrigger>
</Style.Triggers>
</Style>
</TextBox.Style>
</TextBox>
Strangely, this code does work.
<TextBox Text="{Binding ModifiedUser, UpdateSourceTrigger=PropertyChanged}">
<TextBox.Style>
<Style TargetType="{x:Type TextBox}">
<Style.Triggers>
<DataTrigger Binding="{Binding ModifiedBy}"
Value="Anyone">
<Setter Property="IsEnabled"
Value="False" />
</DataTrigger>
<DataTrigger Binding="{Binding ModifiedBy}"
Value="Me">
<Setter Property="IsEnabled"
Value="False" />
</DataTrigger>
</Style.Triggers>
</Style>
</TextBox.Style>
</TextBox>
you have to set the initial isEnabled in your style too. otherwise your "local" IsEnabled=false will always win!
change your style and it will work.
<TextBox Text="{Binding ModifiedUser, UpdateSourceTrigger=PropertyChanged}">
<TextBox.Style>
<Style TargetType="{x:Type TextBox}">
<Setter Property="IsEnabled" Value="False" />
<Style.Triggers>
<DataTrigger Binding="{Binding ModifiedBy}"
Value="Someone">
<Setter Property="IsEnabled"
Value="True" />
</DataTrigger>
</Style.Triggers>
</Style>
</TextBox.Style>