改寫 MessageModel 使其資料內容改變時會發出通知

MessageModel.cs

...
  public class MessageModel : System.ComponentModel.INotifyPropertyChanged
  {
    private string _id;
    public string Id 
    {
      get { return _id; }
      set 
      {
        if (value != _id)
        {
          _id = value;
          NotifyPropertyChanged("Id");
        }
      }
    }

    private string _name;
    public string Name 
    {
      get { return _name; }
      set
      {
        if (value != _name)
        {
          _name = value;
          NotifyPropertyChanged("Name");
        }
      }
    }

    private string _message;
    public string Message
    {
      get { return _message; }
      set
      {
        if (value != _message)
        {
          _message = value;
          NotifyPropertyChanged("Message");
        }
      }
    }

    private string _avatarUrl;
    public string AvatarUrl 
    {
      get { return _avatarUrl; }
      set
      {
        if (value != _avatarUrl)
        {
          _avatarUrl = value;
          NotifyPropertyChanged("AvatarUrl");
        }
      }
    }

    private DateTime _postTime;
    public DateTime PostTime 
    {
      get { return _postTime; }
      set
      {
        if (value.CompareTo(_postTime) != 0)
        {
          _postTime = value;
          NotifyPropertyChanged("PostTime");
        }
      }
    }

    public event PropertyChangedEventHandler PropertyChanged;
    private void NotifyPropertyChanged(String propertyName)
    {
      PropertyChangedEventHandler handler = PropertyChanged;
      if (null != handler)
      {
        handler(this, new PropertyChangedEventArgs(propertyName));
      }
    }
  }
...