Silverlight 4 ComboBox SelectedValue not working when ItemsSource changed

Question

I have 2 properties in ViewModel class, EmployeeList and Employee. EmployeeList is dynamic property, that being said, this property can change at run time. ViewModel class source code is below:

public class SampleViewModel
{
    public ObservableCollection<Employee> EmployeeList { get; set; }
    public Employee { get { ... } set { ... } }
}

View has set its ItemsSource and SelectedValue property to EmployeeList and Employee respectively.

ItemsSource="{Binding EmployeeList, Mode=TwoWay}"
SelectedValue="{Binding Employee, Mode=TwoWay}"

Everythings work well except EmployeeList has changed and Employee does not exist in EmployeeList, step of scenarios is below.

EmployeeList has 2 employee, Mr. A and Mr. B and SelectedValue is Mr. A
EmployeeList has changed to Mr. B and Mr. C, after this time SelectedValue is not work any more. If I set Employee on ViewModel and NotifyPropertyChanged this value won't update on UI or if I selected new Employee from UI this value won't update on ViewModel, the bottom line is View and ViewModel was disconnected since EmployeeList has changed and Employee does not exist in that list.

I want to know how can I fixed these problems?

Ral Zarek · Accepted Answer · 2012-08-28 06:40:12Z

2

I guess you have to bind the combobox like below:

<ComboBox Grid.Row="5" Grid.Column="1" ItemsSource="{Binding Path=Employee,Mode=TwoWay}">
  <DataTemplate>
    <StackPanel>
       <TextBlock Height="8" HorizontalAlignment="Center" Text="{Binding Path=MR.A}"/>
       <TextBlock Height="8" HorizontalAlignment="Center" Text="{Binding Path=MR.B}"/>
     </StackPanel>
  </DataTemplate>
</ComboBox>

edited Aug 28, 2012 at 6:40

Ral Zarek

1,0964 gold badges18 silver badges26 bronze badges

answered Aug 28, 2012 at 5:51

HAIJIA.HOU

212 bronze badges

Sign up to request clarification or add additional context in comments.

Comments

Jaans · Accepted Answer · 2010-12-01 00:04:47Z

0

I too have major issues with the Silverlight 4 ComboBox and SelectedValue bindings. Strangely, using SelectedItem for binding works very well, but that isn't always feasible, especially when using domain objects and FK Id type lookups.

Have a look at my post over at the CSLA forums - it resolve most timing and binding issues when using selected value.

http://forums.lhotka.net/forums/p/9786/45971.aspx

Hope that helps

answered Dec 1, 2010 at 0:04

Jaans

4,6284 gold badges41 silver badges50 bronze badges

Comments

Anonymous · Accepted Answer · 2011-02-08 14:25:42Z

0

I can solved this problem by solution from Silverlight ComboBox Sample for RIA Services.

answered Feb 8, 2011 at 14:25

Anonymous

9,69824 gold badges87 silver badges136 bronze badges

Collectives™ on Stack Overflow

Silverlight 4 ComboBox SelectedValue not working when ItemsSource changed

3 Answers 3

Comments

Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

3 Answers 3

Comments

Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related