Question

我目前正在创建一个测试WPF灵活性的应用程序。我有一些用户控件，当涉及到它的ViewModel时，它们是非常透明的。透明的意思是usercontrol可以使用任何类型的ViewModel，前提是ViewModel具有绑定到该usercontrol中控件的所有必需属性。我这样做是通过将ViewModel指定为特定用户控件的datacontext。

当只有两个用户控件（一个可以访问ViewModelLocator，一个需要前者的datacontext声明）时，这种方法有效。当它达到3层或更多用户控制时，我不知道该怎么做。有没有办法在usercontrol中设置usercontrol的datacontext，该usercontrol驻留在可以访问ViewModelLocator的用户控件中？

以下是一些可以澄清我的问题的代码。

此代码是父usercontrol。它旨在用于使用MAF的应用程序。我使用非静态ViewModelLocator来确保每个插件实例使用不同的ViewModelLocator实例，因为插件没有自己的app.xaml（因此没有全局资源）。如您所见，我从网格中的单独程序集中放置了一个usercontrol，然后声明了它的datacontext，以便所述usercontrol与父usercontrol的ViewModelLocator进行交互。

<UserControl x:Class="TestApp.Inventory.Common.Views.MaterialsNewView"
             xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
             xmlns:vm="clr-namespace:TestApp.Inventory.Common.ViewModel"
             xmlns:views="clr-namespace:TestApp.Inventory.Common.Views"
             xmlns:viewsSupp="clr-namespace:TestApp.Supplier.Common.Views;assembly=TestApp.Supplier.Common"
             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
             xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
             xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
             mc:Ignorable="d" Height="607" Width="616" Loaded="UserControl_Loaded">

    <UserControl.Resources>
        <vm:ViewModelLocator x:Key="Locator" />
    </UserControl.Resources>

    <UserControl.DataContext>
        <Binding Path="MaterialsNewView" Source="{StaticResource Locator}" />
    </UserControl.DataContext>

    <Grid>
        <views:SupplierView x:Name="supplierView" Margin="145,306,0,0" HorizontalAlignment="Left" Width="328" Height="258" VerticalAlignment="Top" DataContext="{Binding Source={StaticResource Locator}, Path=SupplierView}" />
    </Grid>
</UserControl>

然后我有了child usercontrol的代码。就像我之前所说的那样，子用户控件在ViewModel方面是透明的。这就是每次都应该在父usercontrol中声明datacontext的原因。

<UserControl x:Class="TestApp.Supplier.Common.Views.SupplierView"
        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:ignore="http://www.ignore.com"
        mc:Ignorable="d ignore" Height="289" Width="352" 
        xmlns:my="clr-namespace:TestApp.Lookup.Common.Views;assembly=TestApp.Lookup.Common">

    <Grid>
        <my:MaterialTypeListView Height="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=Grid, AncestorLevel=1}, Path=ActualHeight}" HorizontalAlignment="Left" Name="materialTypeListView1" VerticalAlignment="Top" Width="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=Grid, AncestorLevel=1}, Path=ActualWidth}" />
    </Grid>
</UserControl>

我的问题是当子用户控件有自己的子用户控件时。我不知道如何从父usercontrol声明其datacontext。目标是无论有多少个用户控件层，它们都应该与父用户控件的ViewModelLocator进行交互。

Answer 1

将DependencyProperty添加到名为MaterialTypeList的UserControl SupplierView。

public partial class SupplierView
{
    public List<string> MaterialTypeList
    {
        get { return (List<string>)GetValue(MaterialTypeListProperty); }
        set { SetValue(MaterialTypeListProperty, value);}
    }

    public static readonly DependencyProperty MaterialTypeListProperty =
            DependencyProperty.Register("MaterialTypeList", typeof(string), typeof(SupplierView),
            new PropertyMetadata(null));
}

在SupplierView上的UserControl MaterialNewView上添加绑定到MaterialTypeList

 <UserControl x:Class="TestApp.Supplier.Common.Views.SupplierView"
            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:ignore="http://www.ignore.com"
            mc:Ignorable="d ignore" Height="289" Width="352" 
            xmlns:my="clr-namespace:TestApp.Lookup.Common.Views;assembly=TestApp.Lookup.Common">

        <Grid>
            <my:MaterialTypeListView 
DataContext="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=UserControl, AncestorLevel=1}, Path=MaterialTypeList}"
Height="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=Grid, AncestorLevel=1}, Path=ActualHeight}" HorizontalAlignment="Left" Name="materialTypeListView1" VerticalAlignment="Top" Width="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType=Grid, AncestorLevel=1}, Path=ActualWidth}" />
        </Grid>
    </UserControl>

在MaterialTypeListView上的UserControl SupplierView上添加绑定到MaterialTypeList。

    <UserControl x:Class="TestApp.Inventory.Common.Views.MaterialsNewView"
                 xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
                 xmlns:vm="clr-namespace:TestApp.Inventory.Common.ViewModel"
                 xmlns:views="clr-namespace:TestApp.Inventory.Common.Views"
                 xmlns:viewsSupp="clr-namespace:TestApp.Supplier.Common.Views;assembly=TestApp.Supplier.Common"
                 xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
                 xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006" 
                 xmlns:d="http://schemas.microsoft.com/expression/blend/2008" 
                 mc:Ignorable="d" Height="607" Width="616" Loaded="UserControl_Loaded">

        <UserControl.Resources>
            <vm:ViewModelLocator x:Key="Locator" />
        </UserControl.Resources>

        <UserControl.DataContext>
            <Binding Path="MaterialsNewView" Source="{StaticResource Locator}" />
        </UserControl.DataContext>

        <Grid>
            <views:SupplierView x:Name="supplierView" Margin="145,306,0,0" 
MaterialTypeList="{Binding [HERE YOUR LIST OF MATERIALTYPE]}"
HorizontalAlignment="Left" Width="328" Height="258" VerticalAlignment="Top" DataContext="{Binding Source={StaticResource Locator}, Path=SupplierView}" />
        </Grid>
    </UserControl>

无论usercontrol有多少层，都要在usercontrol中设置usercontrol的datacontext

1 个答案: