![wpf treeview hierarchicaldatatemplate example wpf treeview hierarchicaldatatemplate example](https://i.stack.imgur.com/DkAEq.png)
The answer of course is to create templates for each level and in this example this requires two more HierarchicalDataTemplates. As you can see, it ignores any Attributes, but concatenates all the Elements - in this case the Items elements - it finds. The reason for this result is that the data template is targeted specifically at the Name attribute of SalesPerson instances and the TreeView doesn't really know how to display anything else it subsequently finds as it traverses deeper into the data. However, if you expand either of those SalesPersons you will be less pleased with the result: If you run this project as-is, it starts out as you would expect:īoth the Salesperson instances are shown, each on its own node. The XPath setting uses the asterisk notation, which means that the search will begin from the start of the data source (Or from the top of the tree, if you prefer to think of it in those terms). Note the use of a single TreeViewItem and the Binding Source being set to that XMLDataProvider. In order to see the result so far, we'll add a TreeView to the WPF Window. Because the data is XML based, XPath is used in place of the usual Path syntax and the symbol is used to signify that the binding needs to look for an attribute rather than an element. Specifically in this case the template will employ a TextBlock to display the Name of the particular Salesperson instance. The ItemsSource property is easy to use in this case and requires only the inclusion of the 'Binding' extension as shown. Our XML data file contains a type named SalesPerson and each time one is found, the template will be used. Thanks to the magic of WPF DataBinding, this is done almost automatically - that is to say that whenever an instance of the target DataType is found as the binding engine does its work, this template will be used to display it. The DataType identifies the Type to which this template will be applied. The XMLDataProvider can be placed in the Resources collection of the Window:
![wpf treeview hierarchicaldatatemplate example wpf treeview hierarchicaldatatemplate example](https://1.bp.blogspot.com/-5_RWMA-4tNQ/UoH8jVt37_I/AAAAAAAAAl0/IMEY2DMZmp4/s320/Clipboard01.jpg)
To keep things short and simple, I have only included two SalesPerson instances in the demo file. Here is a schematic of the overall structure of the data:Īs you can see from the diagram, each Salesperson can have several children named 'Period', each Period can have several children named ''Order' and each Order can have several children named 'Item'. This has the advantage that you can physically see the tree-like composition of the data.
![wpf treeview hierarchicaldatatemplate example wpf treeview hierarchicaldatatemplate example](https://i.stack.imgur.com/BUGU8.png)
Hopefully, if you too have come unstuck using these kind of templates, this step by step approach might be helpful to you. So I thought I would work through a few samples over the space of a few blogs, building up the complexity as I go. Although I understood the overall theory that they walk the data tree and can create formatted, nested output, I always seemed to spend an inordinately long time trying to get things to work just as I want them (or sometimes, to be truthful, to work at all!) TreeViewAdv allow user to customize the items under a column header by defining a cell template for the TreeViewColumns.For some reason, I struggled with HierarchicalDataTemplates when I first tried to use them. Add ( ) End Sub Public _treeitems As ObservableCollection ( Of Model ) Public ReadOnly Property TreeItems () As ObservableCollection ( Of Model ) If True Then Return _treeitems End If If True Then _treeitems = value End If End Property End Classĭifferent templates can be used for items based on specific constraints using the ItemTemplateSelector.ġ.Create the template selector as shown in the following code snippet: Public class ViewModel : NotificationObject. End If If True Then models_Renamed = value Me. IsCheckable ) End If End Property Public ReadOnly Property Models () As ObservableCollection ( Of Model ) If True Then Return models_Renamed. IsChecked ) End If End Property Private isCheckable As Boolean = False Public ReadOnly Property IsCheckable () As Boolean If True Then Return isCheckable End If If True Then isCheckable = value Me. Caption ) End If End Property Private isChecked As Boolean = False Public ReadOnly Property IsChecked () As Boolean If True Then Return isChecked End If If True Then isChecked = value Me. Empty Public ReadOnly Property Caption () As String If True Then Return caption_Renamed End If If True Then caption_Renamed = value Me. Public Class Model Inherits NotificationObject Public Sub New () Models = New ObservableCollection ( Of Model )() End Sub 'INSTANT VB NOTE: The variable caption was renamed since Visual Basic does not allow variables and other class members to have the same name: Private caption_Renamed As String = String.