Programming WPF, 2nd Edition

Data Binding

Once we've got a set of controls and a way to lay them out, we still need to fill them with data and keep that data in sync with wherever the data actually lives. (Controls are a great way to show data but a poor place to keep it.) For example, imagine that we'd like to build a WPF application for keeping track of people's nicknames. Something like Figure 1-15 would do the trick.

Figure 1-15. Data binding to a collection of custom types

In Figure 1-15, we've got two TextBox controls, one for the name and one for the nickname. We've also got the actual nickname entries in a ListBox in the middle and a Button to add new entries. We could easily build the core data of such an application with a class, as shown in Example 1-25.

Example 1-25. A custom type with data binding support

public class Nickname : INotifyPropertyChanged {
    // INotifyPropertyChanged Member
    public event PropertyChangedEventHandler PropertyChanged;
    void Notify(string propName) {
      if( PropertyChanged != null ) {
        PropertyChanged(this, new PropertyChangedEventArgs(propName));
    }
  }

  string name;
  public string Name {
    get { return name; }
    set {
      name = value;
      Notify("Name"); // notify consumers
    }
  }

  string nick;
  public string Nick {
    get { return nick; }
    set {
      nick = value;
      Notify("Nick"); // notify consumers } } public Nickname( ) : this("name", "nick") { } public Nickname(string name, string nick) { this.name ...