TreeView 和数据绑定失败答案

【问题标题】：TreeView and databinding failedTreeView 和数据绑定失败
【发布时间】：2019-05-10 04:38:55
【问题描述】：

我正在研究 MVVM 模式和 TreeView。

我未能将数据模型与视图绑定。这是我目前的代码：

MainWindow.xaml：

xmlns:reptile="clr-namespace:Terrario.Models.Reptile"
...
<TreeView x:Name="TrvFamily" Grid.Row="1" Grid.Column="0" ItemsSource="{Binding }">
            <TreeView.ItemTemplate>
                <HierarchicalDataTemplate DataType="{x:Type reptile:Family}" ItemsSource="{Binding Items}">
                    <TextBlock Text="{Binding Name}" />
                </HierarchicalDataTemplate>
            </TreeView.ItemTemplate>
        </TreeView>

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

MainWindow.xaml.cs：

    private void LoadFamily()
    {
        FamilyVM familiesVM = new FamilyVM();
        familiesVM.Load();
        TrvFamily.DataContext = familiesVM;
    }
}

ViewModels\FamilyVM：

class FamilyVM
{
    public ObservableCollection<Family> Families { get; set; }

    public void Load()
    {
        ObservableCollection<Family> families = new ObservableCollection<Family>();

        families.Add(new Family { ID = 1, Name = "Amphibian" });
        families.Add(new Family { ID = 2, Name = "Viperidae" });
        families.Add(new Family { ID = 3, Name = "Aranae" });

        Families = families;
    }
}

Models\Family.cs

    class Family
{
    public int ID { get; set; }
    public string Name { get; set; }
}

TreeView 仍然是白色的，就像没有数据一样。

希望你有问题；）

提前致谢

【问题讨论】：

标签： c# wpf mvvm data-binding observablecollection

【解决方案1】：

您正在绑定到 FamilyVM 的实例，而不是 Families。那没有 Name 属性，所以你什么也得不到。

您还应该始终在任何视图模型上实现 inotifypropertychanged。否则会出现内存泄漏。

而且您在 Family 上没有子收藏。

    <TreeView x:Name="TrvFamily" Grid.Row="1"
              ItemsSource="{Binding Families}">
        <TreeView.ItemTemplate>
            <HierarchicalDataTemplate DataType="{x:Type local:Family}" ItemsSource="{Binding SomeCollectionYouDoNotHaveYet}">
                <TextBlock Text="{Binding Name}" />
            </HierarchicalDataTemplate>
        </TreeView.ItemTemplate>
    </TreeView>

通常将 inotifypropertychanged 的东西放在继承视图模型的基类中。

class FamilyVM : INotifyPropertyChanged
{
    private ObservableCollection<Family> families = new ObservableCollection<Family>();

    public ObservableCollection<Family> Families
    {
        get { return families; }
        set { families = value; NotifyPropertyChanged(); }
    }

    public void Load()
    {
        ObservableCollection<Family> families = new ObservableCollection<Family>();
        families.Add(new Family { ID = 1, Name = "Amphibian" });
        families.Add(new Family { ID = 2, Name = "Viperidae" });
        families.Add(new Family { ID = 3, Name = "Aranae" });
        Families = families;
    }
    public event PropertyChangedEventHandler PropertyChanged;
    private void NotifyPropertyChanged([CallerMemberName] String propertyName = "")
    {
        PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
    }
}

【讨论】：