Question

I have quite a simple question regarding WPF. I’ve searched around but didn’t find the “the Answer” yet…

I would like to do a 2-level Data Binding. Simplified, I have a Person with some attributes, that also has N Addresses, each of some type and with some Zip Code (both selectable from a combo).

I retrieve the following Data from the server:

public List<AddressType> AddressTypeList; // catalogue of Address Types
public List<ZipCode> ZipCodeList; // catalogue of Zip Codes

public Person Person; // Person object
public List<Address> PersonAddressList; // Address List for that person (each has AddresType and ZipCode property)

Now, I’d like to bind this data to some controls. So, I put these properties into some custom class (say Data) and set the main user control’s DataContext property to this object:

data = new Data();            

data.AddressTypeList = dao.GetAll<AddressType>();
data.ZipCodeList = dao.GetAll<ZipCode>();
data.Person = dao.GetPerson();
data.PersonAddressList = dao.GetPersonAddressList(Person);

this.DataContext = data; // this == some parent UserControl

Now, my XAML part for Address List looks something like this:

<ListBox Name="listBoxAddressList" ItemsSource="{Binding PersonAddressList}">
    <ListBox.ItemTemplate>
        <DataTemplate>
            <StackPanel Orientation="Horizontal">
                <ComboBox ItemsSource="{Binding AddressTypeList}" SelectedItem="{Binding AddressType}"/>  
                <TextBox Text="{Binding Address}"/> <!-- this works! -->
                <ComboBox ItemsSource="{Binding ZipCodeList}" SelectedItem="{Binding ZipCode}"/>  
            </StackPanel>
        </DataTemplate>
    </ListBox.ItemTemplate>
</ListBox>

The Address property gets bound OK, but the AddressTypeList and ZipCodeList don’t. It’s kind of logical, since the PersonAddress (in PersonAddressList) doesn’t have that property (they are on a different level!). I don’t want to put the whole list of AddressTypes and ZipCodes into each address object, I would like to most painlessly bind it to “parent” or pass it to each Address List Item object somehow in XAML.

I think it’s a common request to have a catalogue of some values in a combo (one list), but one of them is selected and that value is bound to another object’s property. How would that be done properly?

Answer 1

Edit 2: You could also try to set up your lists as static properties, that way you might be able to bind directly using something like:

ItemsSource="{Binding Source={x:Static local:Data.AddressTypeList}}"

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Edit: Try using RelativeSource to get back to the original data, something like this:

<ComboBox ItemsSource="{Binding RelativeSource={RelativeSource AncestorType=ListBox}, Path=DataContext.AddressTypeList}" SelectedValue="{Binding AddressType}"/>

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Also: Bind SelectedValue to the property instead of SelectedItem.

e.g.

<ItemsControl ItemsSource="{Binding Data}" Grid.IsSharedSizeScope="True">
    <ItemsControl.ItemTemplate>
        <DataTemplate>
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition SharedSizeGroup="A"/>
                    <ColumnDefinition SharedSizeGroup="B"/>
                </Grid.ColumnDefinitions>
                <TextBlock Grid.Column="0" Text="{Binding Name}"/>
                <ComboBox Grid.Column="1" SelectedValue="{Binding Occupation}">
                    <sys:String>Programmer</sys:String>
                    <sys:String>GUI Designer</sys:String>
                    <sys:String>Coffee Getter</sys:String>
                </ComboBox>
            </Grid>
        </DataTemplate>
    </ItemsControl.ItemTemplate>
</ItemsControl>