WPF ComboBox 将项目源绑定到 MVVM 中的不同数据上下文 [英] WPF ComboBox bind itemssource to different datacontext in MVVM

问题描述

我有一个用户控件，它的数据上下文设置为名为 EmployeeList_VM 的视图模型.然后，我在该用户控件中有一个 ContentControl，它的 datacontect 设置为视图模型的公共属性 (EmployeeSelection).ContentControl 的数据上下文与同一用户控件内的列表框的选定项绑定相同.

I have a user control that has its datacontext set to a view model called EmployeeList_VM. I then have a ContentControl within that user-control that has its datacontect set to a public property (EmployeeSelection) of the view model. The ContentControl's datacontext is the same as the selected item binding of a listbox within the same user control.

我希望在 ContentControl 中有一个组合框(属于名为 EmployeeStatus 的 observblecollection)，将其选定项绑定到 ContentControl 的 EmployeeSelection 数据上下文的属性.我希望组合框的 itemssource 绑定到父"视图模型 EmployeeList_VM 的公共属性 EmployeeStatus.

I want to have a combobox (of an observblecollection called EmployeeStatus) within the ContentControl bind its selecteditem to a property of the EmployeeSelection datacontext of the ContentControl. I want the itemssource of the combobox to bind to a public property EmployeeStatus of the "parent" viewmodel EmployeeList_VM.

我可以获取显示在组合框中的员工状态列表.我无法将其绑定到 EmployeeSelection 的 idStatus 属性.

I can get a list of the employees status to appear wihtin the combobox. I can not get it to bind to the idStatus property of the EmployeeSelection.

这是我到目前为止的内容(为了可读性删除了一些代码):

Here is What I have so far (some code removed for readability):

<UserControl x:Class="FTC.View.EmployeeListView"
            xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
            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" 
            xmlns:local="clr-namespace:FTC_Application"
            xmlns:i="clr-namespace:System.Windows.Interactivity;assembly=System.Windows.Interactivity"
            xmlns:cmd="http://www.galasoft.ch/mvvmlight"
            mc:Ignorable="d" 
            DataContext="{Binding EmployeeList_VM, Source={StaticResource Locator}}"
            d:DesignHeight="900" d:DesignWidth="1000">

        <Expander x:Name="DetailExpander" Grid.Column="2" Header="employee detail" Style="{DynamicResource ExpanderStyle_FTC}" IsExpanded="True" Padding="8,0,0,10" >
            <Grid>
                <Grid.ColumnDefinitions>
                    <ColumnDefinition Width="Auto"/>
                    <ColumnDefinition Width="*"/>
                </Grid.ColumnDefinitions>
                <StackPanel Orientation="Vertical" HorizontalAlignment="Left" >
                    <Button Content="" Style="{DynamicResource ButtonSave}" Command="{Binding SaveCommand}" ToolTip="Save Changes" Margin="0,0,10,10"/>
                    <Button Content="" Style="{DynamicResource ButtonUndo}" Command="{Binding UndoCommand}" ToolTip="Undo Changes" Margin="0,0,10,10"/>
                </StackPanel>
                <ScrollViewer Grid.Column="1" HorizontalAlignment="Stretch" VerticalAlignment="Stretch">
                    <ContentControl DataContext="{Binding Path=EmployeeSelection, Mode=TwoWay}" >
                            <!-- FTC SETTINGS GRID CONTENT-->
                            <Grid Grid.ColumnSpan="6" Grid.Row="1">
                                <Grid.ColumnDefinitions>
                                    <ColumnDefinition Width="30"/>
                                    <ColumnDefinition Width="*"/>
                                    <ColumnDefinition Width="*"/>
                                    <ColumnDefinition Width="*"/>
                                    <ColumnDefinition Width="*"/>
                                </Grid.ColumnDefinitions>
                                <Grid.RowDefinitions>
                                    <RowDefinition Height="Auto"/>
                                    <RowDefinition Height="Auto"/>
                                    <RowDefinition Height="Auto"/>
                                </Grid.RowDefinitions>

                                <TextBlock x:Name="SettingsHeading" Text="FTC Settings" Style="{StaticResource FTC_DetailHeading}" Grid.ColumnSpan="5"/>

                                <TextBlock Text="Status" Style="{StaticResource FTC_DetailLabelSub}" Grid.Column="1" Grid.ColumnSpan="2" Grid.Row="1"/>
                                <ComboBox Grid.Column="1" Grid.ColumnSpan="2" Grid.Row="2"
                                          Margin="5,5,16,5" Height="37"
                                          ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}},Path=DataContext.EmployeeStatus}"
                                          SelectedItem="{Binding idStatus, Mode=TwoWay}"
                                          SelectedValuePath="idStatus"
                                          DisplayMemberPath="chrCode" FontSize="18"/>

                           </Grid>
                    </ContentControl>
                </ScrollViewer>
            </Grid>
        </Expander>
</UserControl>

我什至尝试对组合框的选定项目进行以下更改(我将 ContentControl DetailControl 命名为):

I even tried the following change (I named the ContentControl DetailControl) for the selected item of the combobox:

SelectedItem="{Binding ElementName=DetailControl, Path=DataContext.idStatus}"

有人可以帮我正确连接选定的项目绑定吗?组合框显示所有正确的项目，但它们不绑定到 EmployeeSelection.idStatus.

Can someone please help me get the selected item binding hooked up properly. The combobox displays all the right items, but they do not bind to the EmployeeSelection.idStatus.

提前致谢.

推荐答案

所以这里对我有用，希望它可以帮助其他人

so here is what worked for me, hope it can help someone else

<ComboBox Name="cbStatus" Grid.Column="1" Grid.ColumnSpan="2" Grid.Row="2"
                                          Style="{StaticResource FTC_DetailComboBox}"
                                          ItemsSource="{Binding RelativeSource={RelativeSource FindAncestor, AncestorType={x:Type UserControl}},Path=DataContext.EmployeeStatus}"
                                          SelectedItem="{Binding ElementName=DetailControl, Path=DataContext.employee_status}"
                                          SelectedValuePath="idStatus"
                                          SelectedValue="{Binding idStatus, Mode=TwoWay, ValidatesOnDataErrors=True}"
                                          DisplayMemberPath="chrCode"/>

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