WPF ComboBox Display Issue - wpf

Question

I have a ComboBox that's bound to a Collection of User objects. The combo's DisplayMemberPath is set to "Name," a property of the User object. I also have a textbox that is bound to the same object that ComboBox.SelectedItem is bound to. As such, when I change the text in the TextBox, my change gets immediately reflected in the combo. This is exactly what I want to happen as long as the Name property isn't set to blank. In such a case, I'd like to substitute a generic piece of text, such as "{Please Supply a Name}". Unfortunately, I couldn't figure out how to do so, so any help in this regard would be greatly appreciated!
<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"
Width="340"
SizeToContent="Height"
WindowStartupLocation="CenterScreen"
ResizeMode="NoResize">
<StackPanel>
<TextBlock Text="ComboBox:" />
<ComboBox SelectedItem="{Binding SelectedUser}"
DisplayMemberPath="Name"
ItemsSource="{Binding Users}" />
<TextBlock Text="TextBox:"
Margin="0,8,0,0" />
<TextBox Text="{Binding SelectedUser.Name, UpdateSourceTrigger=PropertyChanged}" />
</StackPanel>
public class ViewModel : INotifyPropertyChanged
{
private List<User> users;
private User selectedUser;
public event PropertyChangedEventHandler PropertyChanged;
public List<User> Users
{
get
{
return users;
}
set
{
if (users == value)
return;
users = value;
RaisePropertyChanged("Users");
}
}
public User SelectedUser
{
get
{
return selectedUser;
}
set
{
if (selectedUser == value)
return;
selectedUser = value;
RaisePropertyChanged("SelectedUser");
}
}
private void RaisePropertyChanged(string propertyName)
{
var handler = PropertyChanged;
if (handler != null)
handler(this, new PropertyChangedEventArgs(propertyName));
}
}
public class User
{
public string Name { get; set; }
}

Answer 1

Take a look at this post. There are several answers that may meet your requirement.

Answer 2

You can make use of TargetNullValue
<StackPanel>
<TextBlock Text="ComboBox:" />
<ComboBox SelectedItem="{Binding SelectedUser}" ItemsSource="{Binding Users}" >
<ComboBox.ItemTemplate>
<DataTemplate>
<TextBlock
Text="{Binding Name, TargetNullValue='Enter some text'}"/>
</DataTemplate>
</ComboBox.ItemTemplate>
</ComboBox>
<TextBlock Text="TextBox:"
Margin="0,8,0,0" />
<TextBox Text=
"{Binding SelectedUser.Name, UpdateSourceTrigger=PropertyChanged}" />
</StackPanel>
and convert an empty name to null.
public class User
{
private string name;
public string Name
{
get
{
return this.name;
}
set
{
this.name = (string.IsNullOrEmpty(value)) ? null : value;
// probably best raise property changed here
}
}
}