I have a textbox inside of a listbox that I would like to update the ObservableCollection when the textbox loses focus. I tried using my collections CollectionChanged event as described in this post here to try to solve the problem. Right now the only way to update the collection is if I add or remove an item from the listbox. Am I going about this the wrong way? What am I missing for the textbox to update the collection?
MainWindow.xaml
<ListBox ItemsSource="{Binding DataLogList,Mode=TwoWay}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<Label Content="{Binding DataLogLabel}" Margin="5"/>
<TextBox Text="{Binding DataLogName,Mode=TwoWay,UpdateSourceTrigger=LostFocus}" Margin="5" Width="150"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
MainViewModel.cs
public MainViewModel()
{
DataLogList = new ObservableCollection<DataLogContent>();
DataLogList.CollectionChanged += (s, e) =>
{
if (e.NewItems != null)
{
foreach (DataLogContent item in e.NewItems)
{
item.PropertyChanged += item_PropertyChanged;
}
}
if (e.OldItems != null)
{
foreach (DataLogContent item in e.OldItems)
{
item.PropertyChanged -= item_PropertyChanged;
}
}
};
}
void item_PropertyChanged(object sender, PropertyChangedEventArgs e)
{
NotifyPropertyChanged();
}
DataLogContent.cs
public class DataLogContent:ViewModelBase
{
private string dataLogLabel;
public string DataLogLabel
{
get { return this.dataLogLabel; }
set
{
this.dataLogLabel = value;
NotifyPropertyChanged();
}
}
private string dataLogName;
public string DataLogName
{
get { return this.dataLogName; }
set
{
this.dataLogLabel = value;
NotifyPropertyChanged();
}
}
}
I have it working based on this. My guess is that you may be over complicating the adding/removing logic of an item inside the ObservableCollection
. There's no need to monitor the property changed event, as each object will already raise the event whenever a property within it changes.
Here's what I have:
namespace WpfApplication1
{
public class MainViewModel : ViewModelBase
{
public ObservableCollection<DataLogContent> DataLogList { get; private set; }
public MainViewModel()
{
DataLogList = new ObservableCollection<DataLogContent>();
DataLogList.Add(new DataLogContent
{
DataLogLabel = "Label",
DataLogName = "Name"
});
DataLogList.Add(new DataLogContent
{
DataLogLabel = "Label2",
DataLogName = "Name2"
});
}
}
public class DataLogContent : ViewModelBase
{
private string dataLogLabel;
public string DataLogLabel
{
get { return this.dataLogLabel; }
set
{
this.dataLogLabel = value;
OnPropertyChanged("DataLogLabel");
}
}
private string dataLogName;
public string DataLogName
{
get { return this.dataLogName; }
set
{
this.dataLogName = value;
OnPropertyChanged("DataLogName");
}
}
}
}
Simple ViewModelBase:
namespace WpfApplication1
{
public class ViewModelBase : INotifyPropertyChanged
{
public event PropertyChangedEventHandler PropertyChanged;
public void OnPropertyChanged(string property)
{
var handler = PropertyChanged;
if (handler != null)
{
handler(this, new PropertyChangedEventArgs(property));
}
}
}
}
Xaml:
<Window x:Class="WpfApplication1.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
Title="MainWindow" Height="350" Width="525">
<ListBox ItemsSource="{Binding DataLogList,Mode=TwoWay}">
<ListBox.ItemTemplate>
<DataTemplate>
<StackPanel Orientation="Horizontal">
<Label Content="{Binding DataLogLabel}" Margin="5"/>
<TextBox Text="{Binding DataLogName,Mode=TwoWay,UpdateSourceTrigger=LostFocus}" Margin="5" Width="150"/>
</StackPanel>
</DataTemplate>
</ListBox.ItemTemplate>
</ListBox>
</Window>
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