c# - 如何在此模型中应用 MVVM 模式？

Question

问题从这篇文章开始:Using binding to a List<UserControl> how can I do for not showing the controls

我正在设计这样的东西:

List<Container>
(Below container properties)
    - Objective: string
    - Problems: List<ProblemUserControl>

ProblemUserControls 是一个 UserControl，其中包含一个名为 Problem 的额外属性。但是上面的帖子有人建议我使用 MVVM 模式。我正在调查，但我仍然感到困惑，或者我需要一些帮助来理解 WPF 中的模式。

Answer 1

下面是一个例子来说明如何使用 MVVM。请注意，不需要有用户控件列表，实际上从 MVVM 的角度来看，这会被认为是不正确的。

这基于 Visual Studio 中的默认 WPF 应用程序模板。

这里是涉及到的类。

public abstract class ViewModelBase : INotifyPropertyChanged
{
    public event PropertyChangedEventHandler PropertyChanged;

    protected virtual void OnPropertyChanged(string propertyName)
    {
        PropertyChangedEventHandler changed = PropertyChanged;
        if (changed != null)
        {
            changed(this, new PropertyChangedEventArgs(propertyName));
        }
    }
}

public class Container : ViewModelBase
{
    private string m_Objective;
    private ProblemCollection m_Problems;

    public Container()
    {
        m_Problems = new ProblemCollection();
    }

    public string Objective
    {
        get { return m_Objective; }
        set
        {
            m_Objective = value;
            OnPropertyChanged("Objective");
        }
    }

    public ProblemCollection Problems
    {
        get { return m_Problems; }
        set
        {
            m_Problems = value;
            OnPropertyChanged("Problems");
        }
    }
}

public class Problem : ViewModelBase
{
    private string m_Name;

    public string Name
    {
        get { return m_Name; }
        set
        {
            m_Name = value;
            OnPropertyChanged("Name");
        }
    }
}

public class ProblemCollection : ObservableCollection<Problem>
{
}

还有主窗口。请注意，我已注释掉您的矩形以显示绑定(bind)

<Window x:Class="StackOverflowDemo.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">
  <Grid>
    <TextBlock TextWrapping="Wrap" Text="{Binding Objective}" Grid.Column="0" VerticalAlignment="Center"
        FontWeight="Bold" />
    <ItemsControl ItemsSource="{Binding Problems}">
      <ItemsControl.ItemTemplate>
        <DataTemplate>
          <!--<Rectangle Stroke="Black" Height="20" Width="20" Margin="1,0" />-->
          <TextBlock Text="{Binding Path=Name}" />
        </DataTemplate>
      </ItemsControl.ItemTemplate>
    </ItemsControl>
  </Grid>
</Window>

主窗口.cs

public partial class MainWindow : Window
{
    public MainWindow()
    {
        InitializeComponent();

        // Create dummy test data.
        // Normally this will be passed to the window or set externally
        var container = new Container();
        container.Problems.Add(new Problem {Name = "Foo"});
        container.Problems.Add(new Problem {Name = "Bar"});
        container.Problems.Add(new Problem {Name = "hello"});
        container.Problems.Add(new Problem {Name = "world"});

        DataContext = container;
    }
}