MVVM WPF ComboBox with CheckBox

Question

I've tried to search for this for quite some time and haven't found results that help. (perhaps my google-foo needs work?) I'm also fairly new to WPF MVVM, so there is a lot I'm still learning.

My Question is actually in two parts... Firstly, I have a Combobox that has Checkboxes within them within a View. Code:

 <ComboBox Grid.Column="0"
                      Grid.ColumnSpan="5"
                      Margin="15,0,0,0"
          ItemsSource="{Binding StaffNames}" 
                      SelectedValue="{Binding SelectedStaffNames}"
          Grid.Row="4">
                <ComboBox.ItemTemplate>
                    <DataTemplate>
                        <CheckBox Content="{Binding Path=FullName}"
                                  VerticalAlignment="Center"
                                  IsChecked="{Binding RelativeSource={RelativeSource FindAncestor,AncestorType={x:Type ComboBoxItem}},     Path=IsSelected,UpdateSourceTrigger=PropertyChanged,Mode=TwoWay}"
                                  Command="{Binding RelativeSource={RelativeSource Mode=FindAncestor, AncestorType=Window},
                            Path=DataContext.CheckBoxSelected}"
                                  Margin="3">  
                        </CheckBox>
                    </DataTemplate>
                </ComboBox.ItemTemplate>
            </ComboBox>

Everytime I check a checkbox, it seems that the checkboxes get automatically unchecked.

My ViewModel code is as follows.

private bool _isSelected;
        public bool IsSelected
        {
            get
            {
                return _isSelected;
            }
            set
            {
                _isSelected = value;
                RaisePropertyChanged("IsSelected");
            }
        }

What is wrong here?

My second question is: Once the above is resolved, I need to append all checked names (staff names in this case) to a list and pass the values back to a separate view/view model.

I'm at a complete loss for how to accomplish this. Any help or suggestions would be greatly appreciated.

Thanks :)

Why have you specified the `RelativeSource`? The `DataContext` is passed to every child. Are there any binding errors on the output? — Nico Schertler, Feb 21 '13 at 19:51
So far no binding errors. The RelativeSource was added as an "afterthought" to attempt to get the values passed to the ViewModel... This didn't seem to work. It seems to produce the same thing with or without the Command entry — Xyphius, Feb 21 '13 at 20:08
`{Binding RelativeSource={RelativeSource FindAncestor,AncestorType={x:Type ComboBoxItem}}, Path=IsSelected,UpdateSourceTrigger=PropertyChanged,Mode=TwoWay}` so IsChecked is true only when the ComboBoxItem is selected? That makes no sense. I think your design for the control is a bit wonky. Sounds like you should be using a ListBox with checks bound to your Models. — , Feb 21 '13 at 20:46
I'm sort of limited on space for this particular window. A Combobox seemed to be the best solution. — Xyphius, Feb 21 '13 at 20:57

score 0 · Answer 1 · answered Feb 21 '13 at 20:31

0

2 things that could be going wrong

Are you trying to set the check box value in your command - "DataContext.CheckBoxSelected"? Since you already have a binding, this could be resetting the value.
Clicking the checkbox does not update selected item in combo box but only updates the checkbox.

answered Feb 21 '13 at 20:31

Chandramouleswaran Ravichandra

697
7
13

Alright, So I've changed the Checkbox to: IsChecked="{Binding IsSelected}" The "Content" of the Checkbox contains the value... should this be done differently? – Xyphius Feb 21 '13 at 20:36
Well, we should consider this question a duplicate of http://stackoverflow.com/questions/859227/looking-for-a-wpf-combobox-with-checkboxes – Chandramouleswaran Ravichandra Feb 21 '13 at 21:52
wait... how is that a duplicate? – Xyphius Feb 21 '13 at 22:04
How is this not a duplicate? You want a checkbox within the combo box with binding. Thats what the other post talks about. – Chandramouleswaran Ravichandra Feb 21 '13 at 23:03
I already have it binding. what I'm looking for is how to retrieve the data of the content (or text) of the checkbox so that it can be passed to a different view model. – Xyphius Feb 22 '13 at 00:47
That would be your (comboBoxName.SelectedValue as YourViewModel).FullName – Chandramouleswaran Ravichandra Feb 22 '13 at 06:33

MVVM WPF ComboBox with CheckBox

1 Answers1