我尝试学习使用基于树 View 的MVVM。我引用本教程
https://www.codeproject.com/Articles/26288/Simplifying-the-WPF-TreeView-by-Using-the-ViewMode
这非常有帮助，我尝试通过重写代码来理解它
TreeViewViewModel.cs
public class TreeViewViewModel
{
private ObservableCollection<TreeNode> _firstNode;
public static TreeNode _seletectedNode;
private ObservableCollection<TreeNode> _node;
private ICommand _addCommand;
public TreeViewViewModel(TreeNode rootNode) : this(rootNode, null) {}
public TreeViewViewModel(TreeNode rootNode, TreeViewViewModel parentNode)
{
_firstNode = new ObservableCollection<TreeNode>(rootNode.Node);
_node = new ObservableCollection<TreeNode>((from child in rootNode.Node select child).ToList<TreeNode>());
_addCommand = new AddCommand(this);
}
public ObservableCollection<TreeNode> FirstNode
{
get { return _firstNode; }
set { _firstNode = value; }
}
public ObservableCollection<TreeNode> Node
{
get { return _node; }
set { _node = value; }
}
public TreeNode Selected
{
get{ return _seletectedNode; }
set{ _seletectedNode = value;}
}
public ICommand AddCommand
{
get { return _addCommand; }
}
}
TreeNode.cs
public class TreeNode : INotifyPropertyChanged
{
private ObservableCollection<TreeNode> _Node = new ObservableCollection<TreeNode>();
private string _Name;
private string _ID;
private bool _isExpanded;
private bool _isSelected;
public ObservableCollection<TreeNode> Node
{
get { return _Node; }
set
{
_Node = value;
OnPropertyChanged("Node");
}
}
public string Name
{
get { return _Name; }
set { _Name = value; OnPropertyChanged("Name"); }
}
public string ID
{
get { return _ID; }
set { _ID = value; OnPropertyChanged("ID");}
}
public bool IsExpanded
{
get { return _isExpanded; }
set
{
if (value != _isExpanded)
{
_isExpanded = value;
this.OnPropertyChanged("IsExpanded");
}
}
}
public bool IsSelected
{
get { return _isSelected; }
set
{
if (value != _isSelected)
{
_isSelected = value;
this.OnPropertyChanged("IsSelected");
if (_isSelected) {TreeViewViewModel._seletectedNode = this;}
}
}
}
public event PropertyChangedEventHandler PropertyChanged;
protected virtual void OnPropertyChanged(string propertyName)
{
PropertyChanged?.Invoke(this, new PropertyChangedEventArgs(propertyName));
}
}
AddCommand.cs
public class AddCommand : ICommand
{
private TreeViewViewModel _TreeView;
public AddCommand(TreeViewViewModel treeView)
{
_TreeView = treeView;
}
public event EventHandler CanExecuteChanged;
public bool CanExecute(object parameter)
{
return true;
}
public void Execute(object parameter)
{
//Show Selected item
//MessageBox.Show(_TreeView.Selected.Name);
//Add first level item
//_TreeView.FirstNode.Add(new TreeNode { Name = "Hihi" });
//Rename selected item
//_TreeView.Selected.Name = "Hello";
//Remove first level item
//_TreeView.FirstNode.Remove(_TreeView.Selected);
//Add selected item
//_TreeView.Selected.Node.Add(new TreeNode { Name = "Hihi" });
}
}
MainWindown.xaml.cs
public partial class MainWindow : Window
{
public TreeViewViewModel _TreeView;
public MainWindow()
{
InitializeComponent();
TreeNode rootNode = new TreeNode
{
Name = "David",
Node =
{
new TreeNode
{
Name = "Alberto",
Node =
{
new TreeNode
{
Name = "Zena",
Node =
{
new TreeNode
{
Name = "Nick",
}
}
},
new TreeNode
{
Name = "Sarah",
},
}
},
new TreeNode
{
Name = "Komrade",
}
}
};
_TreeView = new TreeViewViewModel(rootNode);
base.DataContext = _TreeView;
}
}
MainWindow.xaml
<Window x:Class="TreeviewMVVM_Test.MainWindow"
xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
xmlns:local="clr-namespace:TreeviewMVVM_Test"
mc:Ignorable="d"
Title="MainWindow" Height="350" Width="525">
<Grid>
<TextBox Margin="10,35,380,260"/>
<Button Margin="154,27,324,268" Command="{Binding AddCommand}" />
<TreeView x:Name="treeView"
ItemsSource="{Binding FirstNode}"
BorderThickness="0"
Height="Auto" Width="Auto"
Margin="21,84,349,19">
<TreeView.ItemContainerStyle>
<Style TargetType="{x:Type TreeViewItem}" BasedOn="{StaticResource {x:Type TreeViewItem}}">
<Setter Property="IsExpanded" Value="{Binding IsExpanded, Mode=TwoWay}" />
<Setter Property="IsSelected" Value="{Binding IsSelected, Mode=TwoWay}" />
<Setter Property="FontWeight" Value="Normal" />
<Style.Triggers>
<Trigger Property="IsSelected" Value="True">
<Setter Property="FontWeight" Value="Bold" />
</Trigger>
</Style.Triggers>
</Style>
</TreeView.ItemContainerStyle>
<TreeView.ItemTemplate>
<HierarchicalDataTemplate ItemsSource="{Binding Node}">
<TextBlock Text="{Binding Name}" />
</HierarchicalDataTemplate>
</TreeView.ItemTemplate>
</TreeView>
</Grid>
</Window>
我的源代码工作正常，我可以从所选节点添加子节点，删除第一级节点，重命名所选节点，获取所选节点。但是只有一件事，我不知道如何存储和获取父节点
我仔细阅读过Josh教程，似乎是父节点存储在构造器中。以下是Josh的代码。如果我使用类似的父节点是TreeViewViewModel，而不是节点。我不想那样，有没有办法使父节点成为TreeNode类型。我想像这样使用_treeView.Seletect.Parent.Name，它应该打印所选节点的父名称。
private PersonViewModel(Person person, PersonViewModel parent)
{
_person = person;
_parent = parent;
_children = new ObservableCollection<PersonViewModel>(
(from child in _person.Children
select new PersonViewModel(child, this))
.ToList<PersonViewModel>());
}
最佳答案
父级不应该是TreeViewViewModel，而应该是TreeNode。
您的TreeNode相当于Josh的PersonViewModel。
在Josh的世界中:Person是模型(数据)PersonViewModel是表示作为树项显示的数据的表示形式。PersonViewModel构造函数带有两个参数。要显示的数据(Person)，以及对父树项目的引用(PersonViewModel)。然后，构造函数通过迭代数据的子项来创建所有子树项(PersonViewModel)。 (Person)
在您的世界中:??是模型(没有任何模型)TreeNode是一些数据的表示，其名称和ID作为树项显示。换句话说，TreeNode既是模型又是 View 模型(不一定是错误的)
但是，您试图在 View 中构造数据，这是错误的。您还将从叶子到根向后构造和向后的树。由于首先要构造子代，因此无法设置父代，因为此时父代不存在。
在Josh的世界中，模型中已经存在层次结构，因此可以使用父级。如果同时构建模型/VM，则需要以其他方式构建树，以便在创建子代之前存在父代。
关于c# - 在Treeview MVVM中获取父项，我们在Stack Overflow上找到一个类似的问题：https://stackoverflow.com/questions/62340104/