MVVM Datagrid ComboBox 数据源未根据选择更新

Question

我在 MVVM 项目中有一个数据网格，它有两个 ComboBox 列。我有一个 DataTable 作为 ItemsSource，还有一个 ObservableObject Collection 作为 ComboBox 项目的来源。存在所选项目的 ObservableObject 实例。

虽然我可以下拉 select 框中的项目，但我的问题是当一个项目被 selected 时，它没有用 select 更新 DataTable 记录]离子。例如，如果在一条记录中，我想在 ComboBox 中将一列设置为“Computer”，稍后查看该记录中的值，它显示为一个空单元格而不是 Computer。

我在绑定 SelectedItem 然后用新 selection 和新记录更新基础 DataTable 方面做错了什么？

    public class AddGroupObjectTypeModel : ObservableObject
    {
        #region Properties
        private int iD;
        public int ID
        {
            get
            {
                return iD;
            }
            set
            {
                if (iD != value)
                {
                    iD = value;
                    OnPropertyChanged();
                }
            }
        }

        private string objType;
        public string ObjType
        {
            get
            {
                return objType;
            }
            set
            {
                if (objType != value)
                {
                    objType = value;
                    OnPropertyChanged();
                }
            }
        }
        #endregion
    }

        private readonly ObservableCollection<AddGroupObjectTypeModel> objectTypeTerms = new()
        {
            new AddGroupObjectTypeModel { ID = 1, ObjType = "User" },
            new AddGroupObjectTypeModel { ID = 2, ObjType = "Group" },
            new AddGroupObjectTypeModel { ID = 3, ObjType = "Computer" }
        };

        public IEnumerable<AddGroupObjectTypeModel> ObjectTypeTerms
        {
            get { return objectTypeTerms; }
        }

        private AddGroupObjectTypeModel selectedObjectTypeTerm = new();
        public AddGroupObjectTypeModel SelectedObjectTypeTerm
        {
            get { return selectedObjectTypeTerm; }
            set { selectedObjectTypeTerm = value; OnPropertyChanged(); }
        }

        private DataTable objectsDisplayTable;
        public DataTable ObjectsDisplayTable
        {
            get { return objectsDisplayTable; }
            set { objectsDisplayTable = value; OnPropertyChanged(); }
        }

            ObjectsDisplayTable = new("Temporary Table");
            ObjectsDisplayTable.Columns.Add("ObjectName", typeof(String));
            ObjectsDisplayTable.Columns.Add("OType", typeof(String));
            ObjectsDisplayTable.Columns.Add("ODomain", typeof(String));

    <DataGrid x:Name="ObjectsTable"
                                          AutoGenerateColumns="False"
                                          Grid.Row="1"
                                          CanUserResizeColumns="True"
                                          Margin="2,0,0,0" 
                                          Style="{StaticResource ThemedDataGrid}"
                                          BorderBrush="{x:Null}"
                                          ItemsSource="{Binding ObjectsDisplayTable,Mode=TwoWay,UpdateSourceTrigger=PropertyChanged}"
                                          HorizontalAlignment="Stretch" 
                                          VerticalAlignment="Stretch"
                                          CanUserAddRows="True"
                                          SelectionMode="Single"
                                          SelectionUnit="Cell" 
                                          >

<DataGridTemplateColumn Header="Type"
                                                        x:Name="OType"
                                                        MinWidth="200"
                                                        >
                                    <DataGridTemplateColumn.CellTemplate>
                                        <DataTemplate>
                                            <ComboBox ItemsSource="{Binding Path=DataContext.ObjectTypeTerms, RelativeSource={RelativeSource AncestorType=DataGrid}}"
                                                      DisplayMemberPath="ObjType"
                                                      SelectedItem="{Binding Path=DataContext.SelectedObjectTypeTerm.ObjType, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged,RelativeSource={RelativeSource AncestorType=DataGrid}}"
                                                      SelectedValue="{Binding Path=DataContext.SelectedObjectTypeTerm.ID, RelativeSource={RelativeSource AncestorType=DataGrid}}"
                                                      SelectedValuePath="ID"
                                                      SelectedIndex="0"
                                                      IsSynchronizedWithCurrentItem="false"
                                                      Style="{StaticResource ComboBoxTheme}"
                                                       />
                                        </DataTemplate>

Answer 1

您应该将 ComboBox 的 SelectedValue 属性绑定到要更新的 DataTable 的列：

<ComboBox ItemsSource="{Binding Path=DataContext.ObjectTypeTerms, RelativeSource={RelativeSource AncestorType=DataGrid}}"
          DisplayMemberPath="ObjType"
          SelectedValuePath="ObjType"
          SelectedValue="{Binding OType, UpdateSourceTrigger=PropertyChanged}"
          SelectedIndex="0"
          Style="{StaticResource ComboBoxTheme}" />

同时绑定到 SelectedValue 和 SelectedItem 是没有意义的。

MVVM Datagrid ComboBox 数据源未根据选择更新

MVVM Datagrid ComboBox DataSource not Updating on Selection

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