WPF combobox selecteditem problem

Question

4.00/5 (2 votes)

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Hi all

I faced some odd problem in my project.

In my application I initialize combobox with my classes. Works as expected.

foreach (MyClass c in Classes)
{
myComboBox.Items.Add(c);
}

I have event in my app which handles those classes and I want combobox select automatically that class as selecteditem. When I debug my app it looks fine, right class goes into combobox, but selecteditem remains null and therefore ui shows empty combobox.

here is snippet of my event..

Event(object sender, EventArgs e)
{
.
.
myComboBox.SelectedItem = e.MyClass; //looks right when debugging, but doest work in Ui side
.
.
}

its odd that combobox cannot handle this because it has that class already initialized in it.

Hope you got idea :)

Cheers!

Posted 25-Feb-11 1:56am

paleGegg0

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3 solutions

Solution 3

You could also consider using a CollectionViewSource[^] to provide a CollectionView[^] and otherwise use the approach outlined by Tarun.K.S.

CollectionView has a CurrentItem[^] property that adds to the functionality of your view-model.

Regards
Espen Harlinn

Posted 25-Feb-11 2:57am

Espen Harlinn

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Tarun.K.S · Accepted Answer · 2011-02-25T02:48:00

In my opinion, you have to set the DataTemplate for that Combobox to display the data.

But you have to set the DataContext of the Combobox to your class.
Do this in you code-behind:

C#

myComboBox.DataContext=Classes;

It goes like this:

XML

<combobox name="myCombobox" itemssource="{Binding}">
<combobox.itemtemplate>
<datatemplate>
<textblock text="{Binding Path=Yourproperty}" />
</datatemplate>
</combobox.itemtemplate>
</combobox>

where "Yourproperty" is the property of that class whose value is to be displayed.

or you can also set the DisplayMemerBinding directly to the ComboBox :

XML

<combobox name="Acombo" itemssource="{Binding}" displaymemberbinding="{Binding Path=Yourproperty}" />

Nish Nishant · Accepted Answer · 2011-02-25T02:43:00

Solution 1

Are you sure they are the same reference? A data-copy of the original instance won't be considered the same.

Posted 25-Feb-11 2:43am

Nish Nishant

Comments

Sergey Alexandrovich Kryukov 25-Feb-11 21:40pm

This is the only reasonable explanation I can see, my 5.
(other Answers simply do not address or workaround the problem)
--SA

paleGegg0 27-Feb-11 12:52pm

Hi there! I havent tested other answers yet, but I dont fully understand yours.. what you mean by referencing? Like I said when debugging my combobox holds right classes as expected, event gives known class to combobox, but still it doesnt react like I want to. If bossible could you provide code snippet?