WPF ComboBox, Display SelectedValue Even If Not In ItemSource

Question

In a WPF ComboBox I need to be able to display a SelectedValue that does not exist in the bound ItemsSource collection.

I've done a fair amount of searching and the only solution I've found so far is to instead bind to Text property and set IsEditable="True". I did use that in another part of my application but that won't work here because I can't risk the user providing invalid data.

In the XAML, the ItemsSource is bound to an ObservableCollection of available WorkEfforts. This list can change over time with items dropping out of the list. The SelectedValue is bound to the property of the SelectedItem on a datagrid, Title.WorkEffort. A title is a seperate task, or change, that has a work effort assigned to it. Once assigned to a Title it shouldn't change, even if the work effort is no longer active.

XAML:

<ComboBox ItemsSource="{Binding Path=WorkEfforts}" SelectedValue="{Binding Path=Title.WorkEffort}" DisplayMemberPath="WorkEffortString" SelectedValuePath="WorkEffortString" IsEnabled="{Path=EditMode}"/>

C# Code:

ObservableCollection<WorkEffort> WorkEfforts = client.GetWorkEfforts();// Gets a list of all active work efforts from database public class WorkEffort { public int WorkEffortID { get; set; } public string WorkEffortString { get; set; } public string ChargeNumber { get; set; } } ChangeTitle Title { get; set;} //SelectedItem on a DataGrid whose ItemsSource is an ObservableCollection of ChangeTitles public class ChangeTitle { public int CommentID { get; set; } public int ChangeID { get; set; } public int TitleID { get; set; } public string WorkEffort { get; set; } }

Any help would be appreciated. Thanks!

Community · Accepted Answer · 2017-05-23 12:16:35Z

5

You can use Text property with IsEditable="True" and IsReadOnly="True"

there also another methods here How to display default text "--Select Team --" in combo box on pageload in WPF?

edited May 23, 2017 at 12:16

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answered Nov 2, 2016 at 6:03

Witsarut Hannapachewin

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2 Comments

Pratik Bhajankar Over a year ago

please read suggestion provided by stackoverflow for writing question over stackoverflow. your question is not much clear for ur requirement

beardedwonder6 Over a year ago

Adding IsReadOnly="True" coupled with IsEditable did the trick. Thanks!

Mat J · Accepted Answer · 2016-11-02 12:02:51Z

ComboBox in readonly mode does not support displaying items that does not exist in the ItemSource, but if you are ready for small trade of, you can achieve something similar.

If you implement INotifyPropertyChanged on ChangeTitle and add a boolean property similar to IsAvailable, and then instead of removing items from the collection WorkEfforts, you can set the IsAvailable to false.

Combine that with an ItemContainerStyle for your ComboBox similar to,

<ComboBox.ItemContainerStyle> <Style TargetType="ComboBoxItem"> <Setter Property="IsEnabled" Value="{Binding Path=IsAvailable}"></Setter> </Style> </ComboBox.ItemContainerStyle>

And you can show the unavailable items and at the same time prevent the users from selecting them. You'll be able to programatically select the unavailable items, but your users won't be able to select them by themselves.

ComboBox DOES supports displaying data out of the collection it's bound to MSDN.
I'm aware of the IsEditable option, but what he wants is normal read only ComboBox which doesn't support the requested behaviour. I've made it clear for future readers, Thanks for the heads up.
Thanks for the answer. I didn't end up using it for this but it gave me some ideas for where I can use it elsewhere. Thanks!

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