How to call treeView.SelectedItemChanged programmatically

Question

In my program I would like to call to a SelectedItemChanged event using c# code-behind, I am just unsure about what to pass as parameters. This is for a TreeViewItem.

//Gets selected item in TreeView
private void TreeOne_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
    MainWindowViewModel.SelectedItem = e.NewValue as TreeViewItem;
}

//I'm calling the SelectedItemChanged event from a RightButtonDown event
private void TreeOne_MouseRightButtonDown(object sender, MouseButtonEventArgs e)
{
    TreeOne_SelectedItemChanged(/* What would go here? **/);
}

Also, when I try to build this I receive this compiler error that pretty much led to this question...

No overload for method TreeOne_SelectedItemChanged takes '0' arguments

I'm hoping that this is an easy question, but if I have not provided enough information, or haven't been clear enough please let me know.

Can you show more code? – Austin T French Aug 20 '13 at 13:02 — Austin T French, Aug 20 '13 at 13:02
Sure, check my question. – Eric after dark Aug 20 '13 at 13:06 — Eric after dark, Aug 20 '13 at 13:06

score 1 · Accepted Answer · answered Aug 20 '13 at 13:26

Adding to @Bart Friederichs' answer and assuming that you have a reference to your TreeView, you could add the following method:

private void SetSelectedItem()
{
     MainWindowViewModel.SelectedItem = TreeOne.SelectedItem;
}

Then you can simply call this from wherever you like:

private void TreeOne_SelectedItemChanged(object sender, RoutedPropertyChangedEventArgs<object> e)
{
    SetSelectedItem();
}

private void TreeOne_MouseRightButtonDown(object sender, MouseButtonEventArgs e)
{
    SetSelectedItem();
}

This works well too, thanks. I changed my answer to this one because I am using this now. — Eric after dark, Aug 20 '13 at 13:30

score 0 · Answer 2 · answered Aug 20 '13 at 13:04

0

The usual design pattern would be to call some kind of processing method, and not to "manually" fire events:

private TreeOne_SelectedItemChaned(object sender, 
                        RoutedPropertyChangedEventArgs<object> e) {
    processChange();
}

Then, from withing your code, you just call processChange(), no need to call TreeOne_SelectedItemChanged.

answered Aug 20 '13 at 13:04

Bart Friederichs

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So where does `processChange()` actually go? If you look at my code you'll see that I have operations being performed under `SelectedItemChanged`. I still want those to happen. – Eric after dark Aug 20 '13 at 13:07
In your case it is interesting. Where would you get `e.NewValue` from when calling from `TreeOne_MouseRightButtonDown` ? – Bart Friederichs Aug 20 '13 at 13:08
Well originally I just tried using `MainWindowViewModel.SelectedItem = e.NewValue as TreeViewItem` in my `TreeOne_MouseRightButtonDown` event, but I received a compiler error having to do with `NewValue`. That's why I am trying to call `SelectedItemChanged` instead. – Eric after dark Aug 20 '13 at 13:12

score 0 · Answer 3 · answered Aug 20 '13 at 13:17

0

try to call

TreeOne_SelectedItemChanged(null, null);

answered Aug 20 '13 at 13:17

Ali Baghdadi

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This will result in a `NullPointerException` on `e.NewValue`. – Bart Friederichs Aug 20 '13 at 13:23
It does, but I just said `if(e == null) return;` and `if(sender == null) return;` – Eric after dark Aug 20 '13 at 13:32

How to call treeView.SelectedItemChanged programmatically

3 Answers3

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