如何使用StaticResource在XAML中定义DataContext [英] How to define DataContext in XAML using StaticResource

问题描述

我想通过XAML中的静态资源声明一个DataContext作为Northwind数据库中Customer的绑定。我可以在代码（C＃）中轻松完成此操作，但想学习如何在XAML中进行操作。我已经尝试了所有可以找到的示例，但是没有一个适合我。我相信问题出在我已标记为[Option1]和[Option2]的两个XAML代码行中。您能否弄清楚该语法的真正含义是什么？

I want to declare a DataContext through a static resource in XAML as a binding for the Customers in the Northwind database. I can do this easily in code (C#) but want to learn how to do in XAML. I have tried all of the examples I can find but none of them work for me. I believe the issue is in the two XAML lines of code I have labeled [Option1] and [Option2]. Can you clarify what the syntax for this really should be?

C＃

namespace DataGridEF
{
    public partial class MainWindow : Window
    {
        public MainWindow()
        {
            InitializeComponent();
            bModel1 bNorthWind = new bModel1();
            //this.DataContext = bNorthWind;
            bNorthWind.GetCustomers();
        }
    }
}

namespace DataGridEF
{
    public class bModel1
    {
        List<Customer> _Customers;
        public List<Customer> Customers
        {
            get { return _Customers; }
            set { _Customers = value; }
        }

        public void GetCustomers()
        {
            NorthwindEntities NorthWind = new NorthwindEntities();
            var CustomerQ = from cust in NorthWind.Customers select cust;
            _Customers = CustomerQ.ToList();
        }

    }
}

XAML

 <Window x:Class="DataGridEF.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"
    xmlns:vm="clr-namespace:DataGridEF">

<Window.Resources>
    <vm:bModel1 x:Key="TheViewModel" />
</Window.Resources>

<Grid>
    <DataGrid AutoGenerateColumns="False" Height="195" 
              HorizontalAlignment="Left" Margin="20,89,0,0" 
              Name="dataGrid1" ItemsSource="{Binding Path=Customers}" 
              [option1]DataContext="{StaticResource TheViewModel}"
              [option2]DataContext=
                  "{Binding Path=., Source={StaticResource TheViewModel}}"
              VerticalAlignment="Top" Width="471" >
        <DataGrid.Columns>
            <DataGridTextColumn Header="Name" Binding="{Binding Path=ContactName}" />
            <DataGridTextColumn Header="Address" Binding="{Binding Path=Address}" />
            <DataGridTextColumn Header="City" Binding="{Binding Path=City}" />
        </DataGrid.Columns>
    </DataGrid>
</Grid>
</Window>

推荐答案

如果要避免将问题与Entities Framework和MSSQL复杂化NorthWind数据库，然后在代码项目 WPF / MVVM快速入门教程

If to avoid complicating the question with Entities Framework and MSSQL NorthWind database, then the good illustration is provided in Example2 sample code of codeproject "WPF/MVVM Quick Start Tutorial"

对于XAML，您应将其开头更改为：

For your XAML you should change the beginning of it to:

<Window x:Class="DataGridEF.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"
    xmlns:vm="clr-namespace:DataGridEF">

<Window.DataContext>
        <vm:bNorthWind />
    </Window.DataContext>
<Grid>
<!---Couldnt check your code due to dependencies on 
     EF and MSSQL NorthWind database

     See the reference for working illustration sample:
 http://www.codeproject.com/Articles/165368/WPF-MVVM-Quick-Start-Tutorial

-->
</Grid>
</Window>

此方法的另一种形式可以在，部分：

Another variation of this approach can be seen in "What is the advantage of setting DataContext in code instead of XAML?", the part:

    <StackPanel.DataContext>
        <local:CustomerViewModel />
    </StackPanel.DataContext>   

将 DataContext 的定义从代码隐藏迁移到XAML是与 StaticResource 或 DynamicResource 的使用无关。请参阅： WPF中的StaticResource和DynamicResource有什么区别？可能在codeproject WPF：StaticResource vs.DynamicResource

Migrating DataContext definition from codebehind to XAML is unrelated to the usage of either StaticResource or DynamicResource. See: What's the difference between StaticResource and DynamicResource in WPF? probably better addressed in codeproject WPF: StaticResource vs. DynamicResource

相关的，有用的和进一步的阅读内容：

Related, helpful and further reading:

• 如何摆脱DataContext InitializeComponent中的StackOverflow异常？


• 为什么在其中绑定MainWindow数据上下文XAML的行为与使用this.datacontext = this进行代码绑定中的行为相同？

• How to get rid of StackOverflow Exception in DataContext InitializeComponent?
• Why does binding the MainWindow datacontext in XAML fail to act the same as binding in the codebehind with this.datacontext=this?

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