数据绑定到嵌套属性？ [英] Data Binding to Nested Properties?

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问题描述

我对WPF和XAML非常新鲜，现在我几天坚持数据绑定！我只想将一些嵌套的属性绑定到一个TextBox和ListView（通过XAML），但我做错了。
这是我的示例代码：



MainWindow.xaml.cs 

 命名空间CounterTestNestedDataBinding 
 {
 public partial class MainWindow：Window 
 {
 public MyModel MyModel {get;组; } 
 
 public MainWindow（）
 {
 InitializeComponent（）; 
 MyModel = new MyModel {MyCounter = new Counter（）}; 
} 
 
 private void Button_Click（object sender，RoutedEventArgs e）
 {
 MyModel.MyCounter.incrementCounter（）; 
} 
} 
}

MyModel.cs 

 命名空间CounterTestNestedDataBinding 
 {
 public class MyModel：INotifyPropertyChanged 
 {
 public Counter _myCounter; 
 public Counter MyCounter 
 {
 get {return _myCounter; } 
 set 
 {
 _myCounter = value; 
 NotifyPropertyChanged（MyCounter）; 
} 
} 
 
 //其他一些成员和属性... 
 
 public event PropertyChangedEventHandler PropertyChanged; 
 private void NotifyPropertyChanged（string property）
 {
 if（PropertyChanged！= null）
 {
 PropertyChanged（this，new PropertyChangedEventArgs（property））; 
} 
} 
 
} 
}

Counter.cs 

 命名空间CounterTestNestedDataBinding 
 {
 public class计数器：INotifyPropertyChanged 
 {
 #region成员
 private int _currentNumber; 
 private ObservableCollection< int> _historyList; 
 #endregion 
 
 #region构造函数
 public Counter（）
 {
 _currentNumber = 0; 
 _historyList = new ObservableCollection< int>（）; 
} 
 #endregion 
 
 #region属性
 public int CurrentNumber 
 {
 get {return _currentNumber; } 
 set 
 {
 _currentNumber = value; 
 NotifyPropertyChanged（CurrentNumber）; 
} 
} 
 
 public ObservableCollection< int> HistoryList 
 {
 get {return _historyList; 
 set 
 {
 _historyList = value; 
 NotifyPropertyChanged（HistoryList）; 
} 
} 
 #endregion 
 
 public void incrementCounter（）
 {
 HistoryList.Add（CurrentNumber）; 
 CurrentNumber ++; 
} 
 
 public override string ToString（）
 {
 return string.Format（CurrentNumber：{0}，HistoryList：{1}，_currentNumber，String .Join（，，_historyList））; 
} 
 
 public event PropertyChangedEventHandler PropertyChanged; 
 private void NotifyPropertyChanged（string property）
 {
 if（PropertyChanged！= null）
 {
 PropertyChanged（this，new PropertyChangedEventArgs（property））; 
} 
} 
} 
}

strong> MainWindow.xaml 

 < Window x：Class =CounterTestNestedDataBinding.MainWindow
 xmlns =http://schemas.microsoft.com/winfx/2006/xaml/presentation
 xmlns：x =http://schemas.microsoft.com/winfx/2006/xaml
 xmlns ：counterTestNestedDataBinding =clr-namespace：CounterTestNestedDataBinding
 Title =MainWindowHeight =350Width =200ResizeMode =NoResizeWindowStartupLocation =CenterScreen
 DataContext ={Binding RelativeSource = {RelativeSource Self}}
> 
< StackPanel Orientation =Vertical> 
< TextBox x：Name =TextBoxCounterCurrentText ={Binding MyModel.MyCounter.CurrentNumber}/> 
< Button Content =ButtonClick =Button_Click/> 
< ListView x：Name =ListViewCounterHistoryHeight =75ItemsSource ={Binding MyModel.MyCounter.HistoryList}>< / ListView> 
< / StackPanel> 
< / Window>

我的问题：


  1. 如何绑定嵌套属性？可能吗？为什么要这样的东西，例如

      Text ={Binding MyModel.MyCounter.CurrentNumber}

    不工作？


  2. XAML中的DataContext设置是否正确？



解决方案

在构造函数中设置您的数据上下文：

  public MainWindow（）
 {
 InitializeComponent（）; 
 MyModel = new MyModel {MyCounter = new Counter（）}; 
 this.DataContext = MyModel; 
}

然后当然您的数据路径会因为您所在的数据而改变绑定在MyModel下。您的绑定应更改如下：

 < StackPanel Orientation =Vertical> 
< TextBox x：Name =TextBoxCounterCurrentText ={Binding MyCounter.CurrentNumber}/> 
< Button Content =ButtonClick =Button_Click/> 
< ListView x：Name =ListViewCounterHistoryHeight =75ItemsSource ={Binding MyCounter.HistoryList}>< / ListView> 
< / StackPanel>

编辑：



通过使用XAML来实现。

 < Window x：Class =WpfApplication1.MainWindow
 xmlns =http ：//schemas.microsoft.com/winfx/2006/xaml/presentation
 xmlns：x =http://schemas.microsoft.com/winfx/2006/xaml
 xmlns：local = clr-namespace：WpfApplication1
 xmlns：system =clr-namespace：System; assembly = mscorlib
 Title =MainWindowHeight =350Width =525> 
< Window.Resources> 
< local：MyModel x：Key =myModal/> 
< /Window.Resources> 
 
< StackPanel Orientation =VerticalDataContext ={StaticResource myModal}> 
< TextBox x：Name =TextBoxCounterCurrentText ={Binding MyCounter.CurrentNumber}/> 
< Button Content =ButtonClick =Button_Click/> 
< ListView x：Name =ListViewCounterHistoryHeight =75ItemsSource ={Binding MyCounter.HistoryList}>< / ListView> 
< / StackPanel>



和代码更改如下： 

  public partial class MainWindow：Window 
 {
 public MyModel MyModel {get;组; } 
 public MainWindow（）
 {
 InitializeComponent（）; 
 // MyModel = new MyModel {MyCounter = new Counter（）}; 
 //this.DataContext = MyModel; 
} 
 
 private void Button_Click（object sender，RoutedEventArgs e）
 {
 var myModel = this.Resources [myModal] as MyModel; 
 if（myModel！= null）
 {
 myModel.MyCounter.incrementCounter（）; 
} 
} 
}

顺便说一句，你应该初始化MyModel构造函数中的 _myCounter


I'm pretty new to WPF and XAML and now I'm stuck with data binding for days! I just wanted to bind some nested properties to a TextBox and ListView (via XAML), but I'm doing it wrong. Here's my Sample Code:

MainWindow.xaml.cs

namespace CounterTestNestedDataBinding
{
    public partial class MainWindow : Window
    {
        public MyModel MyModel { get; set; }

        public MainWindow()
        {
            InitializeComponent();
            MyModel = new MyModel { MyCounter = new Counter() };
        }

        private void Button_Click(object sender, RoutedEventArgs e)
        {
            MyModel.MyCounter.incrementCounter();
        }
    }
}

MyModel.cs

namespace CounterTestNestedDataBinding
{
    public class MyModel : INotifyPropertyChanged
    {
        public Counter _myCounter;
        public Counter MyCounter
        {
            get { return _myCounter; }
            set
            {
                _myCounter = value;
                NotifyPropertyChanged("MyCounter");
            }
        }

        // some other members and properties ...

        public event PropertyChangedEventHandler PropertyChanged;
        private void NotifyPropertyChanged(string property)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(property));
            }
        }

    }
}

Counter.cs

namespace CounterTestNestedDataBinding
{
    public class Counter : INotifyPropertyChanged
    {
        #region Members
        private int _currentNumber;
        private ObservableCollection<int> _historyList;
        #endregion

        #region Constructor
        public Counter()
        {
            _currentNumber = 0;
            _historyList = new ObservableCollection<int>();
        }
        #endregion

        #region Properties
        public int CurrentNumber
        {
            get { return _currentNumber; }
            set
            {
                _currentNumber = value;
                NotifyPropertyChanged("CurrentNumber");
            }
        }

        public ObservableCollection<int> HistoryList
        {
            get { return _historyList; }
            set
            {
                _historyList = value;
                NotifyPropertyChanged("HistoryList");
            }
        }
        #endregion

        public void incrementCounter()
        {
            HistoryList.Add(CurrentNumber);
            CurrentNumber++;
        }

        public override string ToString()
        {
            return string.Format("CurrentNumber: {0}, HistoryList: {1}", _currentNumber, String.Join(",", _historyList));
        }

        public event PropertyChangedEventHandler PropertyChanged;
        private void NotifyPropertyChanged(string property)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(property));
            }
        }
    }
}

MainWindow.xaml

<Window x:Class="CounterTestNestedDataBinding.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:counterTestNestedDataBinding="clr-namespace:CounterTestNestedDataBinding"
        Title="MainWindow" Height="350" Width="200" ResizeMode="NoResize" WindowStartupLocation="CenterScreen"
        DataContext="{Binding RelativeSource={RelativeSource Self}}"
        >
    <StackPanel Orientation="Vertical">
        <TextBox x:Name="TextBoxCounterCurrent" Text="{Binding MyModel.MyCounter.CurrentNumber}"/>
        <Button Content="Button" Click="Button_Click"/>
        <ListView x:Name="ListViewCounterHistory" Height="75" ItemsSource="{Binding MyModel.MyCounter.HistoryList}"></ListView>
    </StackPanel>
</Window>

My questions:

  1. How can I bind nested properties? Is it possible? Why does something like

    Text="{Binding MyModel.MyCounter.CurrentNumber}"

    not work?

  2. Is the "DataContext" set correct in the XAML?

解决方案

Set your data context in the constructor like this:

public MainWindow()
{
    InitializeComponent();
    MyModel = new MyModel { MyCounter = new Counter() };
    this.DataContext = MyModel;
}

and then of course the path to your data changes because the data that you are binding is under MyModel. Your bindings should be changed as follows:

<StackPanel Orientation="Vertical">
    <TextBox x:Name="TextBoxCounterCurrent" Text="{Binding MyCounter.CurrentNumber}"/>
    <Button Content="Button" Click="Button_Click"/>
    <ListView x:Name="ListViewCounterHistory" Height="75" ItemsSource="{Binding MyCounter.HistoryList}"></ListView>
</StackPanel>

EDIT:

This is how you do it by using XAML.

<Window x:Class="WpfApplication1.MainWindow"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:local="clr-namespace:WpfApplication1"
    xmlns:system="clr-namespace:System;assembly=mscorlib"
    Title="MainWindow" Height="350" Width="525" >
<Window.Resources>
    <local:MyModel x:Key="myModal" />
</Window.Resources>

<StackPanel Orientation="Vertical" DataContext="{StaticResource myModal}">
    <TextBox x:Name="TextBoxCounterCurrent" Text="{Binding MyCounter.CurrentNumber}"/>
    <Button Content="Button" Click="Button_Click"/>
    <ListView x:Name="ListViewCounterHistory" Height="75" ItemsSource="{Binding MyCounter.HistoryList}"></ListView>
</StackPanel>

and code changes like this:

 public partial class MainWindow : Window
{
    public MyModel MyModel { get; set; }
    public MainWindow()
    {
        InitializeComponent();
        //MyModel = new MyModel { MyCounter = new Counter() };
        //this.DataContext = MyModel;
    }

    private void Button_Click(object sender, RoutedEventArgs e)
    {
        var myModel = this.Resources["myModal"] as MyModel;
        if (myModel != null)
        {
            myModel.MyCounter.incrementCounter();
        }
    }
}

By the way you should initialize _myCounter in MyModel constructor.

这篇关于数据绑定到嵌套属性？的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！

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