在WPF中设置的DataContext在XAML [英] Setting DataContext in XAML in WPF

问题描述

我有以下code：

MainWindow.xaml

<Window x:Class="SampleApplication.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"
        DataContext="{Binding Employee}">
    <Grid>       
        <Grid.RowDefinitions>
            <RowDefinition Height="Auto" />
            <RowDefinition Height="Auto" />
        </Grid.RowDefinitions>
        <Grid.ColumnDefinitions>
            <ColumnDefinition Width="Auto" />
            <ColumnDefinition Width="200" />
        </Grid.ColumnDefinitions>

        <Label Grid.Row="0" Grid.Column="0" Content="ID:"/>
        <Label Grid.Row="1" Grid.Column="0" Content="Name:"/>
        <TextBox Grid.Column="1" Grid.Row="0" Margin="3" Text="{Binding EmpID}" />
        <TextBox Grid.Column="1" Grid.Row="1" Margin="3" Text="{Binding EmpName}" /> 
    </Grid>
</Window>

Employee.cs

namespace SampleApplication
{
    public class Employee
    {
        public Employee()
        {
            EmployeeDetails employeeDetails = new EmployeeDetails();
            employeeDetails.EmpID = 123;
            employeeDetails.EmpName = "ABC";
        }
    }

    public class EmployeeDetails
    {
        private int empID;
        public int EmpID
        {
            get
            {
                return empID;
            }
            set
            {
                empID = value;
            }
        }

        private string empName;
        public string EmpName
        {
            get
            {
                return empName;
            }
            set
            {
                empName = value;
            }
        }
    }
}

这是很简单的code，我只是想在绑定的EmpID 和 EmpName 属性我Employee.cs类文本文本框的性质MainWindow.xaml但没有什么是出现在我的文本框，这些当我运行code。是结合吧？

This is very simple code and I just want to bind the EmpID and EmpName properties in my Employee.cs class to Text properties of Textboxes in MainWindow.xaml but nothing is appearing in my these textboxes when I am running the code. Is the binding right?

推荐答案

这code总是会失败。

This code will always fail.

由于写的，它说：看一个名为属性雇员在我的DataContext属性，并将其设置为DataContext属性。显然，这是不正确的。

As written, it says: "Look for a property named "Employee" on my DataContext property, and set it to the DataContext property". Clearly that isn't right.

要得到你的code的工作，为的是，你的窗口申报更改为：

To get your code to work, as is, change your window declaration to:

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

这声明了一个新的XAML命名空间（本地），并设置在DataContext到Employee类的一个实例。这将导致您的绑定来显示默认的数据（从你的构造函数）。

This declares a new XAML namespace (local) and sets the DataContext to an instance of the Employee class. This will cause your bindings to display the default data (from your constructor).

然而，这是极不可能的这个其实你想要的是。相反，你应该用员工属性的新类（称它为MainViewModel），您再绑定到，像这样的：

However, it is highly unlikely this is actually what you want. Instead, you should have a new class (call it MainViewModel) with an Employee property that you then bind to, like this:

public class MainViewModel
{
   public Employee MyEmployee { get; set; } //In reality this should utilize INotifyPropertyChanged!
}

现在你的XAML变为：

Now your XAML becomes:

<Window x:Class="SampleApplication.MainWindow"
        xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
        xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
        xmlns:local="clr-namespace:SampleApplication"
        Title="MainWindow" Height="350" Width="525">
    <Window.DataContext>
       <local:MainViewModel/>
    </Window.DataContext>
    ...
    <TextBox Grid.Column="1" Grid.Row="0" Margin="3" Text="{Binding MyEmployee.EmpID}" />
    <TextBox Grid.Column="1" Grid.Row="1" Margin="3" Text="{Binding MyEmployee.EmpName}" />

现在，你可以添加其他的属性，等等。（其他类型，名称）有关详细信息，请参阅实施模型 - 视图 - 视图模型模式

Now you can add other properties (of other types, names), etc. For more information, see Implementing the Model-View-ViewModel Pattern

这篇关于在WPF中设置的DataContext在XAML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！