尝试在已有itemsource的datagrid中添加combobox

<DataGrid ItemsSource="{Binding YourItemSource}">
    <DataGrid.Columns>
        <DataGridTextColumn Header="Name" Binding="{Binding Name}" />
        <DataGridComboBoxColumn Header="Category" SelectedValueBinding="{Binding CategoryId}" DisplayMemberPath="CategoryName" SelectedValuePath="CategoryId">
            <DataGridComboBoxColumn.ElementStyle>
                <Style TargetType="ComboBox">
                    <Setter Property="ItemsSource" Value="{Binding DataContext.Categories, RelativeSource={RelativeSource AncestorType=DataGrid}}" />
                </Style>
            </DataGridComboBoxColumn.ElementStyle>
            <DataGridComboBoxColumn.EditingElementStyle>
                <Style TargetType="ComboBox">
                    <Setter Property="ItemsSource" Value="{Binding DataContext.Categories, RelativeSource={RelativeSource AncestorType=DataGrid}}" />
                </Style>
            </DataGridComboBoxColumn.EditingElementStyle>
        </DataGridComboBoxColumn>
    </DataGrid.Columns>
</DataGrid>