Question

Comboxbox / Listbox WPF - DataBinding Issues

Asked by: JamesBrooksbank007

Hi, I'm having trouble with data after binding it to a WPF combo box or listbox. I have a generic list of objects (generated from Linqs) which I'm binding to a combo box. Now this list will change and when it does I will need to refresh the combo box to add / remove new items in the list.

Now binding works a treat:
combobox1.itemssource = list
combobox1.DisplayMemberPath = "Title"
combobox1.SelectedValuePath = "ID"

The above works however, I cannot remove items from the combo box once databound. If I use combopbox1.items.clear() I get an error message concerning the itemssource.

I therefore removed this and returned to a grittier version of populating the comboxbox by looping through the generic list and adding the objects one at a time.

However, when I use items.clear() I get an "Object reference is missing" error.

Ok so after this I then tried to remove the items one at a time. Again I get the same exception rule. After trawling the net I am still trying to find an answer, please experts, how do I remove these items from a WPF combo box.

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Asked On
2009-01-30 at 08:19:00ID24098833
Tags

WPF Controls

,

Combobox

,

Listbox

,

data binding

Topics

.NET Framework 3.x versions

,

Microsoft Visual C#.Net

,

WPF and Silverlight

Participating Experts
2
Points
500
Comments
3

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Answers

 

by: JamesBrooksbank007Posted on 2009-01-30 at 08:39:48ID: 23510107

IF it helps, when I try and remove the items through items.clear I get the following error:

Operation is not valid while ItemsSource is in use. Access and modify elements with ItemsControl.ItemsSource instead.

 

by: unmeshdavePosted on 2009-02-06 at 11:04:24ID: 23572964

well , in your first case, I guess u can use bidirectional binding. I dont remember exact syntax but GIYF.

 

by: murkingPosted on 2009-03-26 at 14:40:19ID: 23995688

A binding should automatically handle the refresh the combo box. OneWay mode means updates will always occur from source (list) to target (ComboBox.ItemsSource).

<!--Assuming your DataContext is set to the class where "list" is exposed as a property-->
<ComboBox x:Name="mComboBox" ItemsSource="{Binding Path=list, Mode=OneWay}" />
 
// or if you prefer setting the binding in code behind:
Binding binding = new Binding();
binding.Source = list;
binding.Mode = BindingMode.OneWay;
mComboBox.SetBinding(ComboBox.ItemsSourceProperty, binding);

                                              
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