wpf - 在 XAML 中设置元素的 DataContext？

Question

嗨，我想掌握绑定(bind)的窍门。

XAML 代码:

<Window x:Class="WPF_SandBox.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">
    <StackPanel x:Name="stackPanel">
        <TextBox x:Name="textBox_FirstName" Width="200" Margin="0,100,0,0" Text="{Binding Path=FirstName, UpdateSourceTrigger=PropertyChanged}"  />
        <TextBox x:Name="textBox_LastName" Width="200" Margin="0,10,0,0" Text="{Binding Path=LastName, UpdateSourceTrigger=PropertyChanged}" />
        <TextBlock x:Name="textBlock_FullName"  Background="LightBlue" Width="200" Margin="0,10,0,0" Text="{Binding Path=FullName, UpdateSourceTrigger=PropertyChanged}"  />
    </StackPanel>
</Window>

C# 代码:

public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            Person person = new Person { FirstName = "Matt", LastName = "Smith" };
            stackPanel.DataContext = person;

        }
    }

    public class Person : INotifyPropertyChanged
    {
        string firstName;
        string lastName;

        public string FirstName
        {
            get
            { 
                return firstName;
            }
            set
            {
                firstName = value;
                OnPropertyChanged("FirstName");
                OnPropertyChanged("FullName");
            }
        }

        public string LastName
        {
            get { return lastName; }
            set
            {
                lastName = value;
                OnPropertyChanged("LastName");
                OnPropertyChanged("FullName");
            }
        }

        public string FullName
        {
            get
            {
                return String.Format("{0}, {1}",lastName,firstName);
            }
        }

        public event PropertyChangedEventHandler PropertyChanged;

        private void OnPropertyChanged(string propName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propName));
            }
        }
    }

启动时，会显示一个带有 2 个文本框和 1 个文本 block 的窗口。在窗口构造函数中，我创建了一个 person 实例并将 stackPanel 的 DataContext 分配给该实例。第一个文本框绑定(bind)到 Person 类的 FirstName 属性，第二个 TextBox 绑定(bind)到 LastName 属性，最后的 TextBlock 只打印 LastName 属性和 FirstName 属性。如前所述，我在 C# 代码中设置了 stackPanel 的 DataContext。如何在 XAML 中设置它？例如:

<StackPanel x:Name="stackPanel" DataContext="person">
        <TextBox x:Name="textBox_FirstName" Width="200" Margin="0,100,0,0" Text="{Binding Path=FirstName, UpdateSourceTrigger=PropertyChanged}"  />
        <TextBox x:Name="textBox_LastName" Width="200" Margin="0,10,0,0" Text="{Binding Path=LastName, UpdateSourceTrigger=PropertyChanged}" />
        <TextBlock x:Name="textBlock_FullName"  Background="LightBlue" Width="200" Margin="0,10,0,0" Text="{Binding Path=FullName, UpdateSourceTrigger=PropertyChanged}"  />
    </StackPanel>

这不起作用，但正如您所见，我正在尝试在 XAML 中设置 stackPanel 的 DataContext，我该怎么做？

谢谢!

Answer 1

This brief article解释了设置 DataContext 的两种方法:通过 XAML 或通过代码。这是代码:

public class HelloWorldDataContextModel
{
    public string HelloWorld { get; set; }

    public HelloWorldDataContextModel()
    {
        HelloWorld = "Hello world!";   
    }
}

和 XAML:

<Window x:Class="HelloWorldDataContext.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"       
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"        
        xmlns:local="clr-namespace:HelloWorldDataContext"        
        Title="MainWindow" Height="350" Width="525">    

    <Window.Resources>
        <local:HelloWorldDataContextModel x:Key="HelloWorldDataContext" />   
    </Window.Resources>    

    <Grid DataContext="{StaticResource HelloWorldDataContext}">        
        <TextBox HorizontalAlignment="Left" Height="23" Margin="222,127,0,0" TextWrapping="Wrap" Text="{Binding HelloWorld}" VerticalAlignment="Top" Width="120"/>    
    </Grid>
</Window>