I'm a bit puzzled: this works:
<StackPanel Orientation="Horizontal" HorizontalAlignment="Right">
<Label Content="Rol" />
<ComboBox ItemTemplate="{StaticResource listRollen}"
Height="23" Width="150"
SelectedItem="{Binding Path=SelectedRol, UpdateSourceTrigger=PropertyChanged, Mode=TwoWay}"
ItemsSource="{Binding Path=allRollen, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" />
</StackPanel>
and the property for SelectedRol is:
public TblRollen SelectedRol
{
get { return _selectedRol; }
set
{
if (_selectedRol != value)
{
_selectedRol = value;
OnPropertyChanged("SelectedRol");
}
}
}
But this doesn't work:
<StackPanel Orientation="Horizontal" HorizontalAlignment="Right">
<Label Content="Soort" />
<ComboBox ItemTemplate="{StaticResource listSoorten}"
Height="23" Width="150"
ItemsSource="{Binding Path=allSoorten}"
SelectedItem="{Binding Path=SelectedProduct, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"/>
</StackPanel>
with following property SelectedProduct:
public TblProduktSoorten SelectedProduct
{
get { return _selectedPSoort; }
set
{
if (_selectedPSoort != value)
{
_selectedPSoort = value;
OnPropertyChanged("SelectedProduct");
}
}
}
somewhere in my code I set SelectedProduct = p.TblProduktSoorten
and while debugging, I see the property gets set correctly...
If the combobox is in a DataGrid
you must add this:
Mode=TwoWay, UpdateSourceTrigger=PropertyChanged
This might be related to the fact that apparently attribute order does matter , in your second case the ItemsSource
and SelectedItem
declarations are swapped.
Try to use not selected item but value path look at the code sample
<ComboBox Name="projectcomboBox" ItemsSource="{Binding Path=Projects}" IsSynchronizedWithCurrentItem="True" DisplayMemberPath="FullName"
SelectedValuePath="Name" SelectedIndex="0" Grid.Row="1" Visibility="Visible" Canvas.Left="10" Canvas.Top="24" Margin="11,6,13,10">
</ComboBox>
the binding property is
public ObservableCollection<Project> Projects
{
get { return projects; }
set
{
projects = value;
RaisePropertyChanged("Projects");
}
}
I don't know if you fixed it yet, but I encountered the same issue today. It was fixed by making sure the collection for selecteditems was an ObservableCollection.
If you set the SelectedProduct property when SelectedProduct is changed in the property changed event handler, you need to set this property asynchronously.
private void ViewModel_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
if (e.PropertyName == "SelectedProduct")
App.Current.Dispatcher.InvokeAsync(() => SelectedProduct = somevalue);
}
My problem was caused by my own tired brain. Same symptom, maybe it will kick you into seeing your problem.
Setting the SelectedItem must be given an item in the List;! (duhh) Normally this happens naturally but I had a case I got a "Role" from another service (Same object type) and was trying to set it and expecting the combobox to change! ;(
instead of -
Roles = roles;
CurrentRole = role;
remember to do this -
Roles = roles;
CurrentRole = roles.FirstOrDefault(e=> e.ID == role.ID); //(System.Linq)
I think this problem is caused by the type of ItemSource and SelectedItem is mitchmatched .
For example, if the ItemSource is binded to a List of int and the SelectedItem is binded to a string . If you set selected item to null or empty string, the combobox cannot know what item is selected. So the combobox will show nothing.
This might be old but I have not seen the trick that did it for me; I had to add NotifyOnSourceupdate=true
to my SelectedItem
in the ComboBox
This had me stumped for a while inside a DataGrid, using SelectedItem. Everything was fine but I am deserializing the app state which loads the items and also has a selected item. The collection was there but the selected isn't actually visible until I used the Text="{Binding Path=Score.SelectedResult.Offset}"
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<ComboBox ToolTip="Score offset results"
ItemsSource="{Binding Score.SearchResults,UpdateSourceTrigger=PropertyChanged}"
SelectedItem="{Binding Score.SelectedResult, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
Text="{Binding Path=Score.SelectedResult.Offset}"
SelectedValuePath="Offset"
DisplayMemberPath="Offset"/>
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
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