Although somewhat experienced with writing Winforms applications, the... "vagueness" of WPF still eludes me in terms of best practices and design patterns.
Despite populating my list at runtime, my listbox appears empty.
I have followed the simple instructions from this helpful article to no avail. I suspect that I'm missing some sort of DataBind()
method where I tell the listbox that I'm done modifying the underlying list.
In my MainWindow.xaml, I have:
<ListBox ItemsSource="{Binding TopicList}" Height="177" HorizontalAlignment="Left" Margin="15,173,0,0" Name="listTopics" VerticalAlignment="Top" Width="236" Background="#0B000000">
<ListBox.ItemTemplate>
<HierarchicalDataTemplate>
<CheckBox Content="{Binding Name}" IsChecked="{Binding IsChecked}"/>
</HierarchicalDataTemplate>
</ListBox.ItemTemplate>
</ListBox>
In my code-behind, I have:
private void InitializeTopicList( MyDataContext context )
{
List<Topic> topicList = ( from topic in context.Topics select topic ).ToList();
foreach ( Topic topic in topicList )
{
CheckedListItem item = new CheckedListItem();
item.Name = topic.DisplayName;
item.ID = topic.ID;
TopicList.Add( item );
}
}
Which, by tracing through, I know is being populated with four items.
EDIT
I have changed TopicList
to an ObservableCollection
. It still doesn't work.
public ObservableCollection<CheckedListItem> TopicList;
EDIT #2
I have made two changes that help:
In the .xaml file:
ListBox ItemsSource="{Binding}"
In the source code after I populate the list:
listTopics.DataContext = TopicList;
I'm getting a list, but it's not automagically updating the checkbox states when I refresh those. I suspect a little further reading on my part will resolve this.
Use ObservableCollection<Topic>
instead of List<Topic>
Edit
it implements INotifyCollectionChanged interface to let WPF know when you add/remove/modify items
Edit 2
Since you set TopicList
in code, it should be a Dependency Property, not a common field
public ObservableCollection<CheckedListItem> TopicList {
get { return (ObservableCollection<CheckedListItem>)GetValue(TopicListProperty); }
set { SetValue(TopicListProperty, value); }
}
public static readonly DependencyProperty TopicListProperty =
DependencyProperty.Register("TopicList", typeof(ObservableCollection<CheckedListItem>), typeof(MainWindow), new UIPropertyMetadata(null));
Edit 3
To see changes in items
INotifyPropertyChanged
interface in CheckedListItem
(each setter should call PropertyChanged(this, new PropertyChangedEventArgs(<property name as string>))
event)CheckedListItem
from DependencyObject
, and convert Name
, ID
, IsChecked
to dependency propertiestopicList[0] = new CheckedListItem() { Name = ..., ID = ... }
)