Wpf Combobox selectedvalue trigger - wpf

I am trying to change the visibility with a trigger when a particular value in a combobox is selected, and I got the following XAML
<ItemsControl ItemsSource="{Binding AccessControl.Credentials}" >
<ItemsControl.ItemTemplate>
<DataTemplate>
<Grid >
<ComboBox Name="chkFieldType"
SelectedValue="{Binding Path=ValueSourceType,Converter={StaticResource enumstringConv}}"
SelectedValuePath="Tag" SelectionChanged="chkFieldType_SelectionChanged" >
<ComboBoxItem Tag="User">User</ComboBoxItem>
<ComboBoxItem Tag="SessionCredential">Field</ComboBoxItem>
<ComboBoxItem Tag="Inherit">From other Resource</ComboBoxItem>
</ComboBox>
<Border " Visibility="Hidden">
<Border.Resources>
<Style TargetType="{x:Type Border}">
<Style.Triggers>
<DataTrigger Binding="{Binding Path=SelectedValue, ElementName=chkFieldType}" Value="Inherit">
<Setter Property="Visibility" Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
</Border.Resources>
<ComboBox/>
</Border>
In this case a border. The selected value is "Inherit" of type string but the border remainds hidden.

I ran into the same problem and found that you have to set the visibility property using the style only. So instead of having the initial visibility set with:
<Border Visibility="Hidden">
You should set the initial visibility using the style:
<Style TargetType="....">
<Setter Property="Visibility" Value="Hidden"/>
<Style.Triggers>
....
</Style.Triggers>
</Style>
(I know it's kinda overdue but I thought maybe someone else might run into the same problem).

Try SelectedItem.Tag or SelectedItem.Content instead of SelectedValue

Set your binding on SelectedValue, not SelectedItem.SelectedValue. The way you currently have it, it is looking for ComboBoxItem.SelectedValue, which doesn't exist
<DataTrigger Value="Inherit"
Binding="{Binding Path=SelectedValue,
Converter={StaticResource enumstringConv},
ElementName=chkFieldType}">

I think it's because you are putting the DataTrigger in Border.Resources.
Try putting the style in the window.resources, with a x:key in order to apply the style to the border.
I think that the border.resources can not access to a control "outside it's own resources context"

SelectedItem and SelectedValue are two seperate properties on the ComboBox.
Since your ComboBoxItems are all strings you can change
<DataTrigger Binding="{Binding Path=SelectedItem.SelectedValue, ElementName=chkFieldType}" Value="Inherit">
to
<DataTrigger Binding="{Binding Path=SelectedItem, ElementName=chkFieldType}" Value="Inherit">

I ended up setting the visibility manually via the code behind when the selectedItem event is fired..

Related

WPF ComboBox BorderBrush and BorderThickness don't work consistently in style

I'm trying to change the border of a ComboBox to be thicker and red based on a binding value, but the properties don't behave as expected. The code below will correctly set the BorderThickness to 2 when Value is Null, but the BorderBrush doesn't get set to Red; I added the setter for Yellow to test, but it is also not working.
<ComboBox Grid.Column="2"
Margin="0,10"
ItemsSource="{Binding RelativeSource={RelativeSource AncestorType=Window}, Path=DataContext.AllConfigurations}"
DisplayMemberPath="Name"
SelectedItem="{Binding Value}">
<ComboBox.Style>
<Style TargetType="ComboBox">
<Setter Property="BorderBrush" Value="Yellow"/>
<Style.Triggers>
<DataTrigger Binding="{Binding Value}" Value="{x:Null}">
<Setter Property="BorderBrush" Value="Red" />
<Setter Property="BorderThickness" Value="2" />
</DataTrigger>
</Style.Triggers>
</Style>
</ComboBox.Style>
</ComboBox>
In contrast, the following code correctly sets the BorderBrush to Red, but it doesn't change the BorderThickness.
<ComboBox Grid.Column="2"
Margin="0,10"
ItemsSource="{Binding RelativeSource={RelativeSource AncestorType=Window}, Path=DataContext.AllConfigurations}"
DisplayMemberPath="Name"
SelectedItem="{Binding Value}"
BorderBrush="Red"
BorderThickness="2"/>
So, to summarize the problem as I understand it, BorderBrush changes the border color when set directly but not when set from a Setter within a Style; BorderThickness changes the border thickness when set from a Setter within a Style but not when set directly. Can anyone please provide an explanation as to why this is happening and how I can make the border thicker and red when Value is Null?

How to set a property of a different control from a style setter

I have a ListView and inside this another ListView. Whenever I select an item in a child ListView I want the parent of that to be selected in the parent ListView. Example:
<Window>
<Window.Resources>
<!-- Parent ListView ItemsTemplate... Incomplete -->
<DataTemplate x:Key="parentItemTemplate">
<!-- Child ListView -->
<ListView SelectedItem="{Binding ChildSelectedItem}" ItemsSource="{Binding WhateverInParent}">
<ListView.Resources>
<Style TargetType="ListViewItem">
<Trigger Property="IsSelected" Value="True">
<!-- This is what I want to do, but ofc this doesn't work because it produces a compile error saying can't set TargetName in a setter -->
<Setter TargetName="parent" Property="SelectedValue" Value="{Binding DataContext, RelativeSource={RelativeSource AncestorType=ListView}}" />
</Trigger>
</Style>
</ListView.Resources>
</ListView>
</DataTemplate>
</Window.Resources>
<ListView ItemsTemplate="{StaticResource parentItemTemplate}" x:Name="parent" SelectedItem="{Binding ParentSelectedItem}" ItemsSource="{Binding Whatever}"/>
</Window>
How do I get this done? Would prefer it to be in XAML.
You just need to set the ListViewItem.ItemContainerStyle like below to achieve what you want
<ListView ItemsTemplate="{StaticResource parentItemTemplate}" x:Name="parent" SelectedItem="{Binding ParentSelectedItem}" ItemsSource="{Binding Whatever}">
<ListView.ItemContainerStyle>
<Style TargetType="ListViewItem">
<Style.Triggers>
<Trigger Property="IsKeyboardFocusWithin" Value="true">
<Setter Property="IsSelected" Value="true" />
</Trigger>
</Style.Triggers>
</Style>
</ListView.ItemContainerStyle>
</ListView>
You could simply use the InnerControl class to achieve this.
References:
WPF Nested ListViews - selectedValue of parent ListView
Or else you can go for RelativeSource:
How to access controls parent's property in a style
Hope it helps!

Switch ItemsSource dynamically in XAML

I'm trying to switch the itemssource of a treeview depending on a value of a property in my viewmodel. I've tried the code below and the trigger doesnt seem to be firing, can someone tell me where I went wrong?
<Window.Resources>
<Style x:Key="TreeViewItemSource" TargetType="TreeView">
<Style.Triggers>
<DataTrigger Binding="{Binding CurrentReportRequested, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" Value="TollFree">
<Setter Property="ItemsSource" Value="{Binding InsertTFSQueryList, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
</DataTrigger>
</Style.Triggers>
</Style>
</Window.Resources>
<TreeView ItemsSource="{Binding Source={StaticResource TreeViewItemSource}, UpdateSourceTrigger=PropertyChanged, Converter={StaticResource DebugConverter}}" />
Set the ItemsSource in Style otherwise local set value will always holds priority.
Read more about it here - Dependency Property Value Precedence Order.
<Style x:Key="TreeViewItemSource" TargetType="TreeView">
<!-- Set ItemsSource here but you need to separate Style out of it. -->
<Setter Property="ItemsSource"
Value="{Binding Source={StaticResource TreeViewItemSource},
UpdateSourceTrigger=PropertyChanged,
Converter={StaticResource DebugConverter}}"/>
<Style.Triggers>
<DataTrigger Binding="{Binding CurrentReportRequested, Mode=TwoWay,
UpdateSourceTrigger=PropertyChanged}"
Value="TollFree">
<Setter Property="ItemsSource" Value="{Binding InsertTFSQueryList,
Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
</DataTrigger>
</Style.Triggers>
</Style>
Most importantly you have set ItemsSource to the Style and somewhere in converter, you are converting it to actual value. This is the strangest thing I ever looked. How style is convertible to ItemsSource. Refactor the logic and separate out both so that above XAML works for you.
To solve my issue, I used good-old oop...polymorphism.
I used a polymorphic structure in my ViewModel. Now my ItemsSource is bound to one IEnumerable list which holds the base class...which i can equate to any of the derived types.

WPF Default Value (using Style Trigger) with Binding

I'm new to WPF so please bear with me. I have a ComboBox on my WPF window, the ItemSource property is bound to a List of strings property (Countries) and the SelectedItem is bound to a string property (SelectedCountry). Both of these properties are in the code behind - and I'm setting the DataContext to "this" (i.e. the Window).
The ComboBox xaml is:
<ComboBox Name="CountryComboBox"
VerticalAlignment="Center"
Width="200"
ItemsSource="{Binding Path=Countries, Mode=OneTime}"
SelectedItem="{Binding Path=SelectedCountry, Mode=TwoWay}">
</ComboBox>
I wanted to have a default "- Please Select -" option that is displayed when an item is not selected, therefore I placed the following xaml in App.xaml:
<Style TargetType="ComboBox">
<Style.Triggers>
<Trigger Property="SelectedItem" Value="{x:Null}">
<Setter Property="IsEditable" Value="true" />
<Setter Property="IsReadOnly" Value="true" />
<Setter Property="Text" Value="- Please Select -" />
</Trigger>
</Style.Triggers>
</Style>
When my window is first displayed, the combobox does have the "- Please Select -" text as expected. When I then select a value in the combobox, the SelectedCountry gets populated appropriately, but then when I assign "null" to the SelectedCountry property the combobox still has the same selected country when I'd expect it to go back to "- Please Select -". What am I doing wrong?
Thanks.
It may be a better option not to modify the ComboBox and simply overlay a TextBlock over the ComboBox when the SelectedItem is null.
Just wrap the ComboBox and a TextBlock in a Grid and set a DataTrigger on the TextBlock to check if the SelectedItem is null and toggle its Visibility
Example:
<Grid>
<ComboBox x:Name="combo" ItemsSource="{Binding Countries}" SelectedItem="{Binding SelectedItem}" />
<TextBlock x:Name="textblock" Text="- Please Select -" Margin="5,3,0,0" IsHitTestVisible="False">
<TextBlock.Style>
<Style TargetType="TextBlock">
<Setter Property="Visibility" Value="Hidden" />
<Style.Triggers>
<DataTrigger Binding="{Binding SelectedItem,ElementName=combo}" Value="{x:Null}">
<Setter Property="Visibility" Value="Visible" />
</DataTrigger>
</Style.Triggers>
</Style>
</TextBlock.Style>
</TextBlock>
</Grid>
Result:
You need to insert a record into the Countries list that has a value of null and the name " - Please Select - ".
Alternatively I suppose you could extend the ComboBox control and write your own so that you could specify the null vale in the list without having to put a record into the Countries selection.
But of the two, it is much easier to just add a record to Countries.

How to specify a ToolTip for a control in a Style from XAML?

I'm using a the WPF datagrid from the Microsoft CodePlex project. I have a custom control that I want to databind to a field from the row of the datagrid. I can't for the life of me figure out how to specify a tooltip on a datagrid row.
The closest I've come is to use a RowStyle with a Setter to set the tooltip, but this only seems to work for text. When I try to put a ControlTempalte in as the Value for the ToolTip, it displays the result of calling ToString on the ControlTemplate type.
I think I need to set the "Template" property of the ToolTip, but I can't seem to figure out how to do that...
<dg:DataGrid Name="dgResults" AutoGenerateColumns="True">
<dg:DataGrid.RowStyle >
<Style TargetType="{x:Type dg:DataGridRow}">
<Setter Property="ToolTip" >
<Setter.Value>
<ControlTemplate TargetType="{x:Type ToolTip}">
<StackPanel>
<TextBlock>txt1</TextBlock><TextBlock>txt2</TextBlock>
</StackPanel>
</ControlTemplate>
</Setter.Value>
</Setter>
</Style>
</dg:DataGrid.RowStyle>
</dg:DataGrid>
Figured it out... took me about 6 hours...
For some reason, I can't set the value directly using Value.Setter. If I define the content for the tooltip as a static resource though, and then set it in the Style property of the DataGrid.RowStyle it works.
So, the datagrid row style looks like:
<Style TargetType="{x:Type dg:DataGridRow}">
<Setter Property="ToolTip" Value="{StaticResource resKWIC}">
</Setter>
</Style>
</dg:DataGrid.RowStyle>
And the resource is
<Window.Resources>
<StackPanel x:Key="resKWIC">
<TextBlock>f1</TextBlock>
<TextBlock>f2></TextBlock>
</StackPanel>
</Window.Resources>
Thanks!
The key is to use the Property ToolTipService.ToolTip, instead of ToolTip - like this:
<Setter Property="ToolTipService.ToolTip" Value="My Tooltip"/>
I also got this working with a couple of changes; included incase it helps someone.
My Datadrid is bound to a list of custom objects, I wanted to display the string "Name" as a column and the string "text" in the tooltip. The trick for me (newbe) was that I had to include the Text Column and hide it for it to show up in the tooltip, i.e.:
<DataGrid AutoGenerateColumns="False" CanUserAddRows="False" EnableRowVirtualization="False" HorizontalAlignment="Stretch" HorizontalContentAlignment="Stretch" IsReadOnly="True" IsSynchronizedWithCurrentItem="True" ItemsSource="{Binding}" Name="dgrTextGroupText" VerticalContentAlignment="Stretch" Grid.Column="3" Grid.Row="1" Grid.RowSpan="6" CanUserReorderColumns="False" CanUserSortColumns="False">
<DataGrid.Columns>
<DataGridTextColumn Binding="{Binding Name}" Width="*" />
<DataGridTextColumn Binding="{Binding Text}" Width="0" Visibility="Hidden" />
</DataGrid.Columns>
<DataGrid.RowStyle>
<Style TargetType="{x:Type DataGridRow}">
<Style.Triggers>
<Trigger Property="IsMouseOver" Value="True">
<Setter Property="ToolTip" Value="{Binding RelativeSource={RelativeSource Self}, Path=DataContext.text}" />
</Trigger>
</Style.Triggers>
</Style>
</DataGrid.RowStyle>
</DataGrid>
Not sure you can do it through XAML.
A easier way might be to just handle the LoadingRow event. In xaml have something like:
<dg:DataGrid Name="dgResults" AutoGenerateColumns="True"
LoadingRow="dgResults_LoadingRow"
ItemsSource="{Binding ListOfStrings}" />
Then in code behind
void dgResults_LoadingRow(object sender, DataGridRowEventArgs e)
{
DataGridRow row = e.Row;
row.ToolTip = row.DataContext as string;
}
Obviously you will have to change the code depending on how you are populating the data in the datagrid. This is also untested =)
I needed to set the tooltip dynamically based on the cell content. I'm using the tooltip to display text overflow text from the cell. The binding below is from a c# class property named CellText. Thanks to the posts above for allowing me to avoid figuring out the entire thing myself.
<DataGridTextColumn Header="HeaderText" Binding="{Binding DisplayText, Mode=OneWay}" Width="33*">
<DataGridTextColumn.CellStyle>
<Style>
<Setter Property="ToolTipService.ToolTip" Value="{Binding DisplayText, Mode=OneWay}"/>
</Style>
</DataGridTextColumn.CellStyle>
</DataGridTextColumn>
There's no need for the ControlTemplate. If you want the StackPanel in the ToolTip, just set it as:
<Setter Property="ToolTip">
<Setter.Value>
<StackPanel>
<TextBlock>txt1</TextBlock><TextBlock>txt2</TextBlock>
</StackPanel>
</Setter.Value>
</Setter>

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