Simple parent-child listbox problem

2 replies. Latest Post by elmore.adam on July 4, 2009.

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Simple parent-child listbox problem

07-04-2009 5:15 PM |

I have a collection of objects that I have successfully bound to a listbox. Each of those objects has a collection property. When a selection is made, I want to bind ItemsSource of the child listbox to the collection property of the selected object. I know I can do this in code within the SelectionChanged event, but this seems like something I should be able to do relativley simply with some databinding syntax that eludes me to this point.

Example:

public class group
{
   public string name { get; set; }
   public List<person> members { get; set; }
   public override string ToString() { return name; }
}

public class person
{
   public string firstname { get; set; }
   public string lastname { get; set; }
   public override string ToString() { return firstname + " " + lastname; }
}

<ListBox x:Name="lbGroups" ItemsSource="{Binding Path=Groups}"/>
<ListBox x:Name="lbMembers" ItemsSource="???" />

Is there a way to do this with databinding? Or, do I have to use code to get this kind of behavior.

Todd

ZeroKoll

Participant

752 points

130 Posts

Re: Simple parent-child listbox problem

07-04-2009 5:49 PM |

Hey Todd!
You can do this using databinding, but you will still need a little more code. Coonsidering how you are binding this, I guess you have a "parent" object that contains the list of groups. Create a SelectedGroup property on that object. Bind the SelectedItem of the ListBox to the SelectedGroup object with a TwoWay binding. Then bind ListBox two to the SelectedGroup property. Something like this...

public class MyViewModel : INotifyPropertyChanged
{
public Group[] Groups { get; set;}
public Group SelectedGroup { get; set; } // With INotifyPropertyChanged support
}

<ListBox x:Name="lbGroups" ItemsSource="{Binding Path=Groups}" SelectedItem={Binding SelectedGroup, Mode=TwoWay}/>
<ListBox x:Name="lbMembers" ItemsSource="{Binding SelectedGroup.Members}" />

I know that code is not complete, but it should give you an idea...

BTW, this can be done using an element-to-element binding in SL3, but that is unfortunately not available in SL2...

// Chris

elmore.adam