Cast list of object into list of class

Question

I have ObservableCollection from class named A. (ObservableCollection<A>). This collection (lets call it listA) is binded to ListBox (lets call it itemsList). This ListBox has SelectionMode=Extended, so I want to be able to select multiple items. I'm trying to get the selected items of that itemsList. The problem is that the SelectedItems returns list of objects, and I dont know how to "convert" it to ObservableCollection from class A. I need to put it in the xml, for instance, if I have a TextBox binded to string in class A. Example:

<TextBox Text={Binding ElementName=itemsList, Path=SelectedItems.stringA}"/>

And of course that I have the DataContext to that TextBox

Which instance property of ClassA you want to show in textbox then? — Rohit Vats, Dec 22 '13 at 18:28
I have a string thats called stringA, with get and set methods, if thats what you mean. Sorry i'm a beginner — amirm, Dec 22 '13 at 18:33
No, i meant suppose you have two items selected in your listbox. Then of the two selectedItems, which item's stringA property text needs to be shown in textbox? — Rohit Vats, Dec 22 '13 at 18:40
I want the value of stringA to be the same as the first SelectedItem. — amirm, Dec 22 '13 at 18:47
@O.R.Mapper I'm not sure that I really understand this whole workaround. — amirm, Dec 22 '13 at 19:12
@amirm - So answer i posted earlier, did that only. What's an issue with that? — Rohit Vats, Dec 22 '13 at 19:23

score 1 · Accepted Answer · answered Dec 22 '13 at 20:09

Just use this binding:

<TextBox 
    x:Name="MyTextBox"
    TextChanged="TextBoxBase_OnTextChanged"
    Text="{Binding Path=SelectedItems[0].Content, 
    ElementName=MyListBox,
    NotifyOnSourceUpdated=True, 
    UpdateSourceTrigger=PropertyChanged,
    Mode=TwoWay}">
</TextBox>

You will need TextBoxBase_OnTextChanged event handler, which will look like this:

private void TextBoxBase_OnTextChanged(object sender, TextChangedEventArgs e)
{
    MyListBox.SelectedItems.Cast<A>().ToList().ForEach(x => x.Content = MyTextBox.Text);
}

score 0 · Answer 2 · answered Dec 22 '13 at 19:16

0

If you want to show StringA from the first selected item, you can try with binding to index in collection. Something like this:

<TextBox Text={Binding ElementName=itemsList, Path=SelectedItems[0].stringA}"/>

answered Dec 22 '13 at 19:16

Jurica Smircic

6,117
2
22
27

Tried it. It works with single selection but when selecting multiple items and editing the textbox, only the first item changed, while I wanted also all the other selecteditems.stringA to be the same as the first selecteditem.stringA – amirm Dec 22 '13 at 19:29
Well thats a different and more complicated story.I don't think you can solve that with some simple Binding. You will need some more logic, maybe another object that knows the value in the textbox and what items are selected. If you have that then you can update the property in all the selected items. – Jurica Smircic Dec 22 '13 at 19:44

Cast list of object into list of class

2 Answers2