I have a listbox and I want to iterate over a collection of Bars in my Foo-object.
<ListBox DataContext="{Binding Path=Foo.Bars}" >
<ListBox.Items>
<ListBoxItem>
<ContentControl DataContext="{Binding Path=.}" />
</ListBoxItem>
</ListBox.Items>
</ListBox>
This is the datatemplate I want to use.
<DataTemplate DataType="{x:Type Bar}">
<Label Content="hello stackoverflow" />
</DataTemplate>
If I snoop (--> examine by using the tool Snoop) my application, I notice that the entire collection of Bars is bound to the ContentControl, in stead of just 1.
How can I properly bind so the iteration over the collection goes fine?
You can just set the DataTemplate, and WPF does all the work. Set the ItemsSource to a list of Bar items, and then define a DataTemplate for Bar items.
<ListBox ItemsSource="{Binding Path=Foo.Bars}">
<ListBox.Resources>
<DataTemplate DataType="{x:Type Bar}">
<Label Content="hello stackoverflow" />
</DataTemplate>
</ListBox.Resources>
</ListBox>
You could also set the ItemsTemplate directly by using <ListBox.ItemTemplate> instead of <ListBox.Resources>
See Data Binding Overview at MSDN.
First add your namespace to the Window element (Intellisense) :
xmlns:local="clr-namespace:yourenamespace"
Then the following XAML ( in Window.Resources is a clean way to do it ) :
<Window.Resources>
<ObjectDataProvider x:Key="DataProvider" ObjectType="{x:Type local:Foo}"/>
<DataTemplate x:Key="Template" >
<TextBlock Text="{Binding Bar}"/>
</DataTemplate>
</Window.Resources>
Place the Listbox :
<ListBox DataContext="{Binding Source={StaticResource DataProvider}}" ItemsSource="{Binding Bars}" ItemTemplate="DynamicResource Template" />
But, it depends on your code-behind object, you have to set a constructor to initialise public properties within your object which are ObservableCollection<> preferably (There is some restriction rules with object instance in XAML).
Related
This is originally a question about Teleriks TabbedWindow control, but its really a generic.
Question. In a ItemTemplate, how to I bind to both the view and properties of the viewmodel
Below, my datasource is a list of Views (ie UserControls). I want to have the View presented in the ContentControl and some properties of the viewmodel presented in the header.
<telerik:RadTabbedWindow x:Class="Porter.Application.Views.MainWindow"
...
ItemsSource="{Binding Tabs2}">
<telerik:RadTabbedWindow.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding DataContext.TabHeader}" />
</DataTemplate>
</telerik:RadTabbedWindow.ItemTemplate>
<telerik:RadTabbedWindow.ContentTemplate>
<DataTemplate>
<ContentControl Content="{Binding}" />
</DataTemplate>
</telerik:RadTabbedWindow.ContentTemplate>
</telerik:RadTabbedWindow>
UPDATED RESULT AFTER ANSWER FROM mm8
<telerik:RadTabbedWindow
ItemsSource="{Binding Tabs2}" <!--list of ViewModels (lets say ViewModelBase.cs)-->
...>
<telerik:RadTabbedWindow.Resources>
<DataTemplate DataType="{x:Type acc:SearchAccountsViewModel}">
<acc:SearchAccountsView/>
</DataTemplate>
<DataTemplate DataType="{x:Type hello:HelloWorldViewModel}">
<hello:HelloWorldView/>
</DataTemplate>
</telerik:RadTabbedWindow.Resources>
<telerik:RadTabbedWindow.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding TabHeader}" />
</DataTemplate>
</telerik:RadTabbedWindow.ItemTemplate>
<telerik:RadTabbedWindow.ContentTemplate>
<DataTemplate >
<ContentControl Content="{Binding}" />
</DataTemplate>
</telerik:RadTabbedWindow.ContentTemplate>
</telerik:RadTabbedWindow>
The Tab2 property should return an IEnumerable<T> where the type T has some public properties that you bind to in the XAML markup.
It may for example have a TabHeader property that you bind the header of the tab to in the ItemTemplate like this:
<telerik:RadTabbedWindow x:Class="Porter.Application.Views.MainWindow"
...
ItemsSource="{Binding Tabs2}">
<telerik:RadTabbedWindow.ItemTemplate>
<DataTemplate>
<TextBlock Text = "{Binding TabHeader}" />
</ DataTemplate >
</ telerik:RadTabbedWindow.ItemTemplate>
</telerik:RadTabbedWindow>
The ContentTemplate should be resolved automatically provided that you have defined a DataTemplate for the type T in scope of the RadTabbedWindow, for example in your App.xaml. It's in this template that you add your UserControl:
<DataTemplate DataType="{x:Type local:YourClass}">
<local:UserControl1 />
</DataTemplate>
You should not create a UserControl in the view model and add it to Tabs2. This breaks what the MVVM pattern is all about, i.e. separation of concerns. A view model doesn't create views.
If you don't have/want an implicit DataTemplate in App.xaml, you may of course also define the ContentTemplate inline:
<telerik:RadTabbedWindow x:Class="Porter.Application.Views.MainWindow"
...
ItemsSource="{Binding Tabs2}">
<telerik:RadTabbedWindow.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding TabHeader}" />
</DataTemplate>
</telerik:RadTabbedWindow.ItemTemplate>
<telerik:RadTabbedWindow.ContentTemplate>
<DataTemplate>
<local:UserControl1 />
</DataTemplate>
</telerik:RadTabbedWindow.ContentTemplate>
</telerik:RadTabbedWindow>
The key point is that you bind to properties of T in both templates and that T is a POCO and not a control of some kind.
I check those articles about doing DataTemplate :
WPF DataTemplate Binding
WPF DataTemplate and Binding
WPF DataTemplate Textblock binding
and thoses about DataTemplate depending on property type :
WPF DataTemplate Binding depending on the type of a property
Dynamically display a control depending on bound property using WPF
I'm trying to display a property with different controls depending of the property value. I have this Xaml that is partialy working. I have 2 problems :
The property is displaying with the right control, but when I set the value it doesn't go back to the property. Means the "set" of My property is not call (but was before I creates the DataTemplate). I detect that the problem about setting the property is about the ="{Binding Path=.}" but I cannot find the solution to set it otherwise.
Also To be able to make it work, I had to "isolate" the Value into a single ViewModel so that the DataTemplate doesn't affect all the other control.
Can you help me find betters solutions to resolves those 2 problems?
Here is the xaml code of my View linked with MyContainerViewModel that has a "ChangingDataType" :
<UserControl >
<UserControl.Resources>
<!-- DataTemplate for strings -->
<DataTemplate DataType="{x:Type sys:String}">
<TextBox Text="{Binding Path=.}" HorizontalAlignment="Stretch"/>
</DataTemplate>
<!-- DataTemplate for bool -->
<DataTemplate DataType="{x:Type sys:Boolean}">
<CheckBox IsChecked="{Binding Path=.}" />
</DataTemplate>
<!-- DataTemplate for Int32 -->
<DataTemplate DataType="{x:Type sys:Int32}">
<dxe:TextEdit Text="{Binding Path=.}" MinWidth="50" Mask="d" MaskType="Numeric" HorizontalAlignment="Stretch"/>
<!--<Slider Maximum="100" Minimum="0" Value="{Binding Path=.}" Width="100" />-->
</DataTemplate>
<!-- DataTemplate for decimals -->
<DataTemplate DataType="{x:Type sys:Decimal}">
<!-- <TextBox Text="{Binding Path=.}" MinWidth="50" HorizontalAlignment="Stretch" />-->
<dxe:TextEdit Text="{Binding Path=.}" MinWidth="50" Mask="f" MaskType="Numeric" HorizontalAlignment="Stretch" />
</DataTemplate>
<!-- DataTemplate for DateTimes -->
<DataTemplate DataType="{x:Type sys:DateTime}">
<DataTemplate.Resources>
<DataTemplate DataType="{x:Type sys:String}">
<TextBlock Text="{Binding Path=.}"/>
</DataTemplate>
</DataTemplate.Resources>
<DatePicker SelectedDate="{Binding Path=.}" HorizontalAlignment="Stretch"/>
</DataTemplate>
</UserControl.Resources>
<ContentPresenter Content="{Binding MyChangingPropery}"/>
</UserControl>
More informations about 2 :
I wanted to have in a view a label and a property that changes depending of the object. Something like this :
<UserControl>
<UserControl.Resources>
<!-- ...DataTemplate here... -->
</UserControl.Resources>
<StackPanel>
<Label Content="Allo"/>
<ContentPresenter Content="{Binding MyChangingPropery}"/>
</StackPanel>
</UserControl>
But if I put the DataTemplate on this UserControl resources, it will also affect the Label "allo". So I had to create another view that contains the DataTemplate and MyChangingProperty so that the label Allo would not be affected. But the extra View created just for one property is kind of ugly to me, I'm sure there is a better way to isolate the DataTemplate so it can apply only to one UIControl.
<UserControl >
<StackPanel>
<Label Content="Allo"/>
<ContentPresenter Content="{Binding MyContainerViewModel}"/>
</StackPanel>
</UserControl>
Note : MyContainerViewModel here is linked with the first view described.
Thanks in advance!
One possible solution would be to use a DataTemplateSelector. You cannot bind primitive types using two way bindings because that would have to be somehow by reference via the DataTemplate which I think is not supported by WPF.
The DataTemplateSelector now selects the right DataTemplate based on the property type and searches for the right DataTemplate in the resources by name. This also solves your problem that your DataTemplates interacted with the Label.
So first you need to define a DataTemplateSelector that changes the DataTemplate based on the type of the property:
public class MyDataTemplateSelector : DataTemplateSelector
{
public override DataTemplate SelectTemplate(object item, DependencyObject container)
{
var fe = (FrameworkElement)container;
var prop = (item as MyViewModelType)?.MyChangingProperty;
if (prop is string)
return fe.FindResource("MyStringDT") as DataTemplate;
else if (prop is bool)
return fe.FindResource("MyBoolDT") as DataTemplate;
// More types...
return base.SelectTemplate(item, container);
}
}
Then you need to change the UserControl like this:
<UserControl>
<UserControl.Resources>
<local:MyDataTemplateSelector x:Key="MyDTSelector" />
<!-- DataTemplate for strings -->
<DataTemplate x:Key="MyStringDT">
<TextBox Text="{Binding MyChangingProperty, Mode=TwoWay}"
HorizontalAlignment="Stretch"/>
</DataTemplate>
<!-- DataTemplate for bool -->
<DataTemplate x:Key="MyBoolDT">
<CheckBox IsChecked="{Binding MyChangingProperty, Mode=TwoWay}" />
<!-- More DataTemplates... -->
</DataTemplate>
</UserControl.Resources>
<StackPanel>
<Label Content="Allo"/>
<ContentPresenter Content="{Binding MyContainerViewModel}"
ContentTemplateSelector="{StaticResource MyDTSelector}" />
</StackPanel>
</UserControl>
You can find a bit more information regarding the DataTemplateSelector here.
You can of course also set a DataType on this new DataTemplates but it isn't required because the x:Key makes them unique anyway. But if you want then it has to look like this:
<DataTemplate x:Key="MyStringDT" DataType="{x:Type local:MyViewModelType}">
In my opinion, the previously posted answer is overkill. While a DateTemplateSelector is a useful thing to know about, it seems unnecessary to me in this scenario.
But if I put the DataTemplate on this UserControl resources, it will also affect the Label "allo".
The reason it affects the Label object is that the Label object is a ContentControl, and so does the same template-matching behavior for content types as your own ContentPresenter element does. And you've set the content of the Label object to a string value. But you can put anything you want as the content for it.
The way to fix the undesired effect is to intercept that behavior by changing the content from a string object to an explicit TextBlock (the control in the template that a string object normally gets assigned). For example:
<UserControl>
<UserControl.Resources>
<!-- ...DataTemplate here... -->
</UserControl.Resources>
<StackPanel>
<Label>
<TextBlock Text="Allo"/>
</Label>
<ContentPresenter Content="{Binding MyChangingPropery}"/>
</StackPanel>
</UserControl>
In that way, you bypass the template-finding behavior (since TextBlock doesn't map to any template and can be used directly), and the content for the Label will just be the TextBlock with the text you want.
This seems like a lot simpler way to fix the issue, than either to create a whole new view or to add a DataTemplateSelector.
I want to do a binding to a collection of homemade custom controls.I've a collection of objects (called Parameters), each one of these should be presented in a panel by a custom control.
I have the following in my main window:
<ItemsControl Grid.Column="1"
ItemsSource="{Binding Path=Parameters}">
</ItemsControl>
And I have a resource file to declare how to view each Parameter object:
<DataTemplate DataType="{x:Type path:Parameter}">
<Grid>
<myControls:MyUserControl
Parameter="{Binding RelativeSource={RelativeSource Self}}">
</myControls:MyUserUserControl>
</Grid>
</DataTemplate>
My control takes a Parameter so I want to bind it to itself for every item in the collection. How can I do that binding?
In a DataTemplate that serves as ItemTemplate in an ItemsControl, the DataContext holds the individual items of the source collection. Hence the binding should look like this:
<myControls:MyUserControl Parameter="{Binding}" />
and the ItemsControl may be written like this to explicitly use the DataTemplate:
<ItemsControl ItemsSource="{Binding Path=Parameters}">
<ItemsControl.ItemTemplate>
<DataTemplate>
<Grid>
<myControls:MyUserControl Parameter="{Binding}" />
</Grid>
</DataTemplate>
</ItemsControl.ItemTemplate>
</ItemsControl>
I have a TabControl where the ContentTemplate is defined by a DataTemplate containing a ContentPresenter. The mapping UIElement class is defined by a DataTemplate for the specific ViewModel type. It works like that:
<UserControl.Resources>
<DataTemplate DataType="{x:Type ViewModels:DiagramVM}">
<Controls:Diagram DataContext="{Binding}" x:Name="diagram"/>
</DataTemplate>
</UserControl.Resources>
<TabControl ItemsSource="{Binding Path=Tabs, Mode=TwoWay}" SelectedIndex="{Binding Path=SelectedTabIndex}"
x:Name="AnalysisTabCtrl" Template="{DynamicResource ScrollableTabControlTemplate}">
<TabControl.ItemTemplate>
<DataTemplate>
<Label Content="{Binding Path=Header}"/>
</DataTemplate>
</TabControl.ItemTemplate>
<TabControl.ContentTemplate>
<DataTemplate>
<ContentPresenter Content="{Binding Path=ViewModel}"/>
</DataTemplate>
</TabControl.ContentTemplate>
</TabControl>
My problem is that I need the instance of the instantiated UIElements. In this case the Diagram instances. How can I get them?
You can use the ItemsControl.ItemContainerGenerator to get a TabItem out of your TabControl, then you can use FindName on the TabItem.ContentTemplate to search for named instantiated controls. (Here you would probably need to name the content-presenter and then again search in its ContentTemplate)
I would not recommend doing anything like that, if you cannot manage without this you probably did not bind all the relevant properties to your items.
I want to achieve the following:
My ViewModel exposes a property named 'Categories' which is a collection of CategoryViewModel objects
Each CategoryViewModel object exposes a property called 'Items' which is a collection of strings*.
On my View, I want a TabControl with a TabItem for each object in the 'Categories' collection.
The Content of each TabItem should be a xceed DataGrid control displaying the contents of the selected tab's Items collection.
<TabControl ItemsSource="{Binding Categories}">
<TabControl.ItemTemplate>
<DataTemplate>
<TextBlock Text="{Binding CategoryName}" />
</DataTemplate>
</TabControl.ItemTemplate>
<TabControl.ContentTemplate>
<DataTemplate>
<xcdg:DataGridControl
ItemsSource="{Binding Items}"
AutoCreateColumns="True">
</xcdg:DataGridControl>
</DataTemplate>
</TabControl.ContentTemplate>
</TabControl>
This works ok when I bind directly to the ItemsSource property of the DataGridControl. However, in order to utilize all of the functionality of the DataGridControl, I need to bind the ItemsSource property of the DataGridControl to a DataGridCollectionViewSource object that is bound to my Items collection. I do this when the grid ISN'T nested in another control by creating a DataGridCollectionViewSource object in the Resources section of the UserControl and binding to that.
<UserControl>
<UserControl.Resources>
<xcdg:DataGridCollectionViewSource x:Key="GridData"
Source="{Binding Items}" />
</UserControl.Resources>
<Grid>
<xcdg:DataGridControl
ItemsSource="{Binding Source={StaticResource GridData}}"
AutoCreateColumns="True">
</xcdg:DataGridControl>
</Grid>
</UserControl>
How do I need to structure the XAML so that when the TabControl is being bound, a DataGridCollectionViewSource object is created for each TabItem so that the DataGridControl that is generated within the content of the TabItem can be bound to it?
Clear as mud, right? :)
Thanks!
Notes:
*In the real solution the collection contains objects of a class that is more complex than a simple string, but a string was used to make the example more simple.
OK, this is a bit of a long-shot, but could you use the DataGrid.Tag ...
<TabControl.ContentTemplate>
<DataTemplate>
<xcdg:DataGridControl
ItemsSource="{Binding RelativeSource={RelativeSource Self}, Path=Tag}"
AutoCreateColumns="True">
<xcdg:DataGridControl.Tag>
<xcdg:DataGridCollectionViewSource x:Key="GridData"
Source="{Binding Items}" />
</xcdg:DataGridControl.Tag>
</xcdg:DataGridControl>
</DataTemplate>
</TabControl.ContentTemplate>
Or ... resources can be defined on any FrameworkElement, so you could try:
<TabControl.ContentTemplate>
<DataTemplate>
<xcdg:DataGridControl
ItemsSource="{Binding Source={StaticResource GridData}}"
AutoCreateColumns="True">
<xcdg:DataGridControl.Resources>
<xcdg:DataGridCollectionViewSource x:Key="GridData"
Source="{Binding Items}" />
</xcdg:DataGridControl.Resources>
</xcdg:DataGridControl>
</DataTemplate>
</TabControl.ContentTemplate>
I don't use the eXceed Grid so cannot test whether these work - just a couple of ideas to try!
Colin E.
You can use x:Shared="True" attribute on a resource. That means a new instance is created for every use of that resource.
Example:
<UserControl.Resources>
<xcdg:DataGridCollectionViewSource x:Key="GridData"
x:Shared="False"
Source="{Binding Items}" />
</UserControl.Resources>