CODEWITHSUNDEEP
wpftreeview.net-6.0selecteditemselectedvalue
Faqit
Faqit

Reputation: 35

Why both TreeView.SelectedValue and SelectedItem are the model instance instead of SelectedItem being a TreeViewItem?

In the TreeView that I work with, I need to determine the parent node of the currently selected node. It is bound to an ObservableCollection<SomeModel> in the viewmodel. When I inspect the currently selected node, both SelectedValue and SelectedItem point to the same instance of SomeModel. How can I find the parent node then? Everything I read on TreeView.SelectedItem suggests to use VisualTreeHelper.GetParent() but it takes a DependencyObject, not a user's model, which is totally reasonable. The binding is as follows:

<TreeView x:Name="treeViewAvailable" ItemsSource="{Binding AvailableSchemas}">

The collection in the viewmodel is as follows:

ObservableCollection<Models.Schema>? _availableSchemas;
public ObservableCollection<Models.Schema>? AvailableSchemas
{
    get => _availableSchemas;
    set
    {
        _availableSchemas = value;
        NotifyPropertyChanged(MethodBase.GetCurrentMethod().Name);
    }
}

The Schema model class contains Tables that we see in the screenshot:

public ObservableCollection<Table> Tables { get; set; } = new();

Having in the past worked with frameworks in which SelectedItem was always the GUI component's ViewItem and SelectedValue was the actual model, I do not understand whether something is wrong with the XAML binding and/or viewmodel/model or whether it is by design of WPF that SelectedItem and SelectedValue both are the instance of the model, which feels wrong.

enter image description here

I see answers on SO that instruct to rig models that themselves track parent-child relationships, and that is the definition of having to write boilerplate code. It cannot be that WPF has nothing for working with TreeView nodes.

This contradicts documentation that clearly states that SelectedItems has to be of type TreeViewItem:

To change the value of a selected item in a TreeView, use the SelectedItem property to access the TreeViewItem.

Upvotes: 0

Views: 36

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