wpf - How to Bind ComboBox Inside ItemsControl with Caliburn.Micro?

Question

This is my project using WPF with Caliburn.Micro. In my view I have an ItemsControl that bound to a BindableCollection, in the coresponding ViewModel, of a record class (MemberVotes). The class just has two fields: MemberName and Vote. The ViewModel also has a second BindableCollection of type string (VoteOptions). The Handle method in the ViewModel loads the data into both BindableCollections. The MemberVotes is loaded from the database and the VoteOptions is loaded by adding a new string collection via code.

I am able to Display The MemberName and Vote in Textboxes with no problem, but I cannot get the ComboBox to bind the the collection of vote options. There are no error messages. The ComboBoxes are just empty.

How do I bind the ComboBoxes to the VoteOptions and then set the selected item for each ComboBox to the Vote?

Any help would be greatly appreciated.

The View (MemberVoteView):

<ItemsControl x:Name="MemberVotes">
    <ItemsControl.ItemTemplate>
        <DataTemplate>

        <Grid>
            <Grid.ColumnDefinitions>
                <ColumnDefinition Width="4*" />
                <ColumnDefinition Width="*" />
                <ColumnDefinition Width="*" />
            </Grid.ColumnDefinitions>

            <TextBox Text="{Binding MemberName}" Grid.Column="0" IsReadOnly="True" />

            <ComboBox Grid.Column="1" ItemsSource="{Binding RelativeSource={RelativeSource AncestorType=ItemsControl}, Path=DataContext.MemberVoteView.VoteOptions}" />

            <TextBox Grid.Column="2" Text="{Binding Vote}" />
        </Grid>

        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>

The ViewModel (MemberVoteViewModel):

    public BindableCollection<MemberVoteModel> MemberVotes { get; set; }

    public BindableCollection<string> VoteOptions { get; set; }

    public void Handle()
    {
        MemberVotes = new BindableCollection<MemberVoteModel>();
        MemberVotes .AddRange(GetVotes());

        VoteOptions = new BindableCollection<string>();
        VoteOptions.AddRange( new string[] { "Y", "N", "NV", "E", "O"} );
    }

标签： wpfcomboboxbindingcaliburn.microitemscontrol

Answer 1

I hope I understood your question correctly. Your problem lies with the following line.

<ComboBox Grid.Column="1" ItemsSource="{Binding RelativeSource={RelativeSource AncestorType=ItemsControl}, Path=DataContext.MemberVoteView.VoteOptions}" />

The DataContext of the ItemsControl is your ViewModel. It doesn't have a property called MemberVoteView. What you needed to have instead was

<ComboBox Grid.Column="1" ItemsSource="{Binding RelativeSource={RelativeSource AncestorType=ItemsControl}, Path=DataContext.VoteOptions}" />

To set the SelectedItem to Vote, you need to bind the SelectedItem Property of ComboBox to MemberVotes.Vote.

For Example,

<ComboBox Grid.Column="1" ItemsSource="{Binding RelativeSource={RelativeSource AncestorType=ItemsControl}, Path=DataContext.VoteOptions}" SelectedItem="{Binding Vote}" />