WPF ComboBox 将项目源绑定到 MVVM 中的不同数据上下文
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WPF ComboBox bind itemssource to different datacontext in MVVM
提问by J King
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中列表框的选定项绑定相同。
I want to have a combobox (of an observblecollection called EmployeeStatus) within the ContentControl bind its selecteditem to a property of the EmployeeSelectiondatacontext of the ContentControl. I want the itemssource of the combobox to bind to a public property EmployeeStatusof the "parent" viewmodel EmployeeList_VM.
我想有（被称为observblecollection的组合框的employeeStatus的ContentControl中绑定其将selectedItem内）到的属性EmployeeSelection的ContentControl中的datacontext的。我希望ComboBox绑定到一个公共财产的ItemsSource的employeeStatus“父”视图模型的EmployeeList_VM。
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.
我可以获得要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。
Here is What I have so far (some code removed for readability):
这是我到目前为止所拥有的（为了可读性而删除了一些代码）：
<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>
I even tried the following change (I named the ContentControl DetailControl) for the selected item of the combobox:
我什至尝试对组合框的选定项目进行以下更改（我将其命名为 ContentControl DetailControl）：
SelectedItem="{Binding ElementName=DetailControl, Path=DataContext.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.
有人可以帮我正确连接选定的项目绑定。组合框显示所有正确的项目，但它们不绑定到 EmployeeSelection.idStatus。
Thanks in advance.
提前致谢。
回答by J King
so here is what worked for me, hope it can help someone else
所以这对我有用，希望它可以帮助别人
<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"/>
