如何将记录添加到数据网格并从另一个窗口更新？

Question

我在更新数据网格的内容时遇到问题。我想从用户填写信息的另一个窗口向数据网格添加一行。然后单击按钮时，数据网格应更新并显示添加的行。然而现在，它没有，我无法弄清楚我做错了什么。

因此，在添加帐户时，它应该使用新添加的记录更新主窗口中的数据网格。

现在，当我想从同一个窗口添加记录时，这就是我添加记录的方式（效果很好）

    public ObservableCollection<Account> ListAccountInfo { get; } = new ObservableCollection<Account>();

    public MainWindow()
    {
        InitializeComponent();
        ListAccountInfo.Add(new Account
        {
            IsSelected = true,
            qweqwe = "test123",
            qweqwe = "test123",
            qwe = "N/A",
            qwe = "N/A",
            qwe = "N/A",
            qwe = "N/A",
            qwe = "N/A",
            qwe = "N/A"
        });
    }

但是当我尝试从另一个窗口（带有表单的窗口）后面的代码中执行相同的操作时，它不会将新记录添加到列表中。

Account 类只是一堆get；放;。不包含任何其他内容（如果需要，我可以添加它..）

我希望有人可以帮助我解决这个问题。我还没有 wpf 的经验❤

Answer 1

最简单的解决方案是为两个窗口使用共享的DataContext 实例，并使用ICommand 将新的Account 项目实际添加到集合中：

RelayCommand.cs
实现取自Microsoft Docs: Patterns - WPF Apps With The Model-View-ViewModel Design Pattern - Relaying Command Logic

public class RelayCommand : ICommand
{
    #region Fields 
    readonly Action<object> _execute;
    readonly Predicate<object> _canExecute;
    #endregion // Fields 
    #region Constructors 
    public RelayCommand(Action<object> execute) : this(execute, null) { }
    public RelayCommand(Action<object> execute, Predicate<object> canExecute)
    {
        if (execute == null)
            throw new ArgumentNullException("execute");
        _execute = execute; _canExecute = canExecute;
    }
    #endregion // Constructors 
    #region ICommand Members 
    [DebuggerStepThrough]
    public bool CanExecute(object parameter)
    {
        return _canExecute == null ? true : _canExecute(parameter);
    }
    public event EventHandler CanExecuteChanged
    {
        add { CommandManager.RequerySuggested += value; }
        remove { CommandManager.RequerySuggested -= value; }
    }
    public void Execute(object parameter) { _execute(parameter); }
    #endregion // ICommand Members 
}

ViewModel.cs

public class ViewModel : INotifyPropertyChanged
{
  public ViewModel()
  {
    this.NewAccount = new Account();
    this.ListAccountInfo = new ObservableCollection<Account>()
    {
      new Account
      {
        IsSelected = true,
        Username = "test123",
        qweqwe = "test123",
        qwe = "N/A",
        qwe = "N/A",
        qwe = "N/A",
        qwe = "N/A",
        qwe = "N/A",
        qwe = "N/A"
      }
    };
  }

  public ObservableCollection<Account> ListAccountInfo { get; }

  private Account newAccount;
  public Account NewAccount
  {
    get => this.newAccount;
    set
    {
      this.newAccount = value;
      OnPropertyChanged();
    }
  }

  public ICommand AddAccountCommand 
  { 
    get => new RelayCommand(
      param => 
      {
        this.ListAccountInfo.Add(this.NewAccount);
        this.NewAccount = new Account();
      });  
  }

  #region Implementation of INotifyPropertyChanged

  public event PropertyChangedEventHandler PropertyChanged;

  [NotifyPropertyChangedInvocator]
  protected virtual void OnPropertyChanged([CallerMemberName] string propertyName = null)
  {
    this.PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
  }
  #endregion Implementation of INotifyPropertyChanged

}

App.xaml

<Application>
  <Application.Resources>

    <!-- Globally shared ViewModel instance -->
    <ViewModel x:Key="ViewModel" />  
  </Application.Resources>
</Application>

MainWindow.xaml

<Window>
  <Window.DataContext>
    <StaticResource ResourceKey="ViewModel" />
  </Window.DatContext>

  <DataGrid ItemsSource="{Binding ListAccountInfo}" />
</Window>

DialogWindow.xaml

  <Window.DataContext>
    <StaticResource ResourceKey="ViewModel" />
  </Window.DatContext>

  <StackPanel>
    <TextBox Text="{Binding NewAccount.Username}" />
    <Button Content="Add" 
            Command="{Binding AddAccountCommand}" />   
  </StackPanel>
</Window>