在wpf数据网格中绑定组合框
我有一个在视图模型的初始化中填充的列表：
ListOfEmployees = new List<EmployeeBO>(employeeRepository.GetEmployees(true, true));
我试图在数据网格中获取一个组合框以从此列表中填充。
<DataGridTemplateColumn Header="U/M" MinWidth="145">
<DataGridTemplateColumn.CellEditingTemplate>
<DataTemplate>
<ComboBox Name="cboUnitMeasure"
ItemsSource="{Binding Path=ListOfUnitMeasures}"
DisplayMemberPath="UnitMeasureDescription" SelectedValuePath="UnitMeasureValue"
SelectedValue="{Binding UnitMeasureValue, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
HorizontalAlignment="Left" Width="140" />
</DataTemplate>
</DataGridTemplateColumn.CellEditingTemplate>
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding UnitMeasureDescription}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
当 dg 加载时，单元格模板显示 UnitMeasureDescription 值，但是当我单击单元格进行编辑时，组合框中没有任何项目。另一方面，当我使用 xml 文件中的静态资源作为项目源（使用相同的属性名称）时，组合框包含项目：
<DataGridTemplateColumn Header="U/M" MinWidth="145">
<DataGridTemplateColumn.CellEditingTemplate>
<DataTemplate>
<ComboBox Name="cboUnitMeasure"
ItemsSource="{Binding Source={StaticResource UnitMeasureData}}"
DisplayMemberPath="UnitMeasureDescription" SelectedValuePath="UnitMeasureValue"
SelectedValue="{Binding UnitMeasureValue, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
HorizontalAlignment="Left" Width="140" />
</DataTemplate>
</DataGridTemplateColumn.CellEditingTemplate>
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding UnitMeasureDescription}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
我在虚拟机中填充 ListOfEmployees 后放置了一个断点，它包含项目。我还验证了 DisplayMemberPath 和 SelectedValuePath 中的属性名称是否正确。不知道我在这里做错了什么。
I have a list that I populate in the init of my viewmodel:
ListOfEmployees = new List<EmployeeBO>(employeeRepository.GetEmployees(true, true));
I am trying to get a combobox in a datagrid to populate from this list.
<DataGridTemplateColumn Header="U/M" MinWidth="145">
<DataGridTemplateColumn.CellEditingTemplate>
<DataTemplate>
<ComboBox Name="cboUnitMeasure"
ItemsSource="{Binding Path=ListOfUnitMeasures}"
DisplayMemberPath="UnitMeasureDescription" SelectedValuePath="UnitMeasureValue"
SelectedValue="{Binding UnitMeasureValue, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
HorizontalAlignment="Left" Width="140" />
</DataTemplate>
</DataGridTemplateColumn.CellEditingTemplate>
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding UnitMeasureDescription}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
When the dg loads, the cell template displays the UnitMeasureDescription value, but when I click on the cell to edit, there are no items in the combobox. On the other hand, when I use a static resource from an xml file as the itemsource-using the same property names-the combobox contains the items:
<DataGridTemplateColumn Header="U/M" MinWidth="145">
<DataGridTemplateColumn.CellEditingTemplate>
<DataTemplate>
<ComboBox Name="cboUnitMeasure"
ItemsSource="{Binding Source={StaticResource UnitMeasureData}}"
DisplayMemberPath="UnitMeasureDescription" SelectedValuePath="UnitMeasureValue"
SelectedValue="{Binding UnitMeasureValue, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
HorizontalAlignment="Left" Width="140" />
</DataTemplate>
</DataGridTemplateColumn.CellEditingTemplate>
<DataGridTemplateColumn.CellTemplate>
<DataTemplate>
<TextBlock Text="{Binding UnitMeasureDescription}" />
</DataTemplate>
</DataGridTemplateColumn.CellTemplate>
</DataGridTemplateColumn>
I put a breakpoint just after populating ListOfEmployees in my vm and it contains items. I also verified the property names in the DisplayMemberPath and SelectedValuePath are correct. Not sure what I am doing wrong here.
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评论（1）
“ListOfUnitMeasures”是 VM 上的属性还是 EmployeeBO 的属性？好的，假设 DataGrid 的 ItemsSource 设置为
List并且 VM 上还有另一个名为“ListUnitOfMeasures”的列表，这是我的解释：DataGrid 中每一行的 DataContext 将相等到 DataGrid 的 ItemsSource 中的元素。在您的例子中，每一行都将使用 EmployeeBO 作为其 DataContext。由于“ListOfUnitMeasures”不是 Employee BO 的属性，因此组合框上的绑定将不起作用，因此不会显示任何内容。
一种可能的解决方案是更改 ComboBox 上的 Binding 以使用指向父 DataGrid 的相对源，如下所示：
Is "ListOfUnitMeasures" a property on the VM or a property of an EmployeeBO? Ok, assuming that the DataGrid's ItemsSource is set to the
List<EmployeeBO>and that there's another list on the VM called "ListUnitOfMeasures", here's my explanation:The DataContext of each row in the DataGrid will be equal to the elements in the DataGrid's ItemsSource. In your case, each row will use an EmployeeBO as its DataContext. And since the "ListOfUnitMeasures" isn't a property of Employee BO, the Binding on the ComboBox will not work and thus won't display anything.
One possible solution is change the Binding on your ComboBox to use a RelativeSource pointing back to the parent DataGrid as follows: