Question

上下文

使用Entity Framework 6我有一个Airframe对象的ObservableCollection，每个对象都有一个Identity对象的从属集合。通过XAML和一个视图模型，我一次在一个DataGrid中查看每个机身（主机）的一个机身（主机）。为了一次只处理一个机身的显示/更新，我正在使用CollectionView，以便在集合中获得当前定位，并可以连接“转到下一个”和“转到上一个”按钮和命令。简化的代码提取：

背后的代码

private ADBContext databaseContext;
private UnitOfWork unitOfWork;
private ViewModels.ViewModel ViewModel;
public MainWindow()
{
    InitializeComponent();

    databaseContext = new ADBContext();
    unitOfWork = new UnitOfWork(databaseContext);

    ViewModel = new ViewModels.ViewModel(unitOfWork);

    this.DataContext = ViewModel;
}

查看模型

    public class ViewModel : INotifyPropertyChanged
    {         
        public CollectionView AirframeCollectionView { get; set; }

        public IUnitOfWork UnitOfWork;

        public ViewModel(IUnitOfWork unitOfWork)
        {
            UnitOfWork = unitOfWork;

            AirframeCollectionView = CollectionViewSource.GetDefaultView(new ObservableCollection<Airframe>(UnitOfWork.Airframes.GetAirframesForRegistration(SearchRegistration)));

            RaisePropertyChanged("AirframeCollectionView");
        }

        public event PropertyChangedEventHandler PropertyChanged;

        public void RaisePropertyChanged(string propertyName)
        {
            if (PropertyChanged != null)
            {
                PropertyChanged(this, new PropertyChangedEventArgs(propertyName));
            }
        }
    }

XAML - Master

<Grid.ColumnDefinitions>
    <ColumnDefinition Name="airframeLabels" MaxWidth="100"/>
    <ColumnDefinition Name="airframeDetails"/>
</Grid.ColumnDefinitions>
<Grid.RowDefinitions>
    <RowDefinition Name="typeRow"/>
    <RowDefinition Name="constructionNoRow"/>
    <RowDefinition Name="remarksRow"/>
    <RowDefinition Name="rolledOutDateRow"/>
    <RowDefinition Name="firstFlightDateRow"/>
    <RowDefinition Name="statusRow"/>
</Grid.RowDefinitions>
<Label Grid.Column="0" Grid.Row="0">Type</Label>
<wpf:AutoCompleteTextBox Grid.Column="1" Grid.Row="0" 
                         Text="{Binding Path=AirframeCollectionView/TypeName}"
                         Provider="{Binding TypeNameStubSuggestions}"/>
<Label Grid.Column="0" Grid.Row="1">Construction no</Label>
<TextBox Grid.Column="1" Grid.Row="1" Margin="5" Name="constructionNo" 
         Text="{Binding AirframeCollectionView/ConstructionNumber}"/>
<Label Grid.Column="0" Grid.Row="2">Remarks</Label>
<TextBox Grid.Column="1" Grid.Row="2" Margin="5" Name="remarks"
         Text="{Binding AirframeCollectionView/Remarks}"/>
 <Label Grid.Column="0" Grid.Row="3">Rolled out</Label>
 <DatePickerTextBox Grid.Column="1" Margin="5" Grid.Row="3" Name="rolledOut" 
                    Text="{Binding AirframeCollectionView/RolloutDate, StringFormat=\{0:dd-MMM-yy\}}"/>
<Label Grid.Column="0" Grid.Row="4">First flight</Label>
<DatePickerTextBox Grid.Column="1" Margin="5" Grid.Row="4" Name="firstFlight" 
                   Text="{Binding AirframeCollectionView/FirstFlightDate, StringFormat=\{0:dd-MMM-yy\}}"/>
<Label Grid.Column="0" Grid.Row="5">Status</Label>
<ComboBox Grid.Column="1" Grid.Row="5" Margin="5" Name="status"
          ItemsSource="{Binding AirframeStatuses}"
          SelectedValue="{Binding AirframeCollectionView/StatusId, Mode=TwoWay}"
          SelectedValuePath="StatusId"
          DisplayMemberPath="StatusName"
          SelectedItem="{Binding AirframeCollectionView/StatusId}"/>

XAML - 明细

<DataGrid Name="identitiesGrid"
          AutoGenerateColumns="False"
          ItemsSource="{Binding AirframeCollectionView/Identities, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}"
          IsReadOnly="False">
    <DataGrid.Columns>
        <DataGridTextColumn Header="Regn" Binding="{Binding Registration, Mode=TwoWay, UpdateSourceTrigger=PropertyChanged}" IsReadOnly="False"/>
</DataGrid>

问题

这样可以完美地显示数据，我可以毫无问题地编辑主数据。当我单击详细信息DataGrid中的任何行时，第一次单击选择单元格，第二次单击导致异常“在带有'EditItem'的PresentationFramework.dll中发生未处理的类型'System.InvalidOperationException'异常不允许这个观点`“。

问题

如何停止此例外？

Answer 1

如何停止此例外？

您需要确保“身份”属性的类型支持编辑。它应该实现IList接口。的HashSet＆LT; T＆GT;例如，但不是List＆lt; T＆gt;和ObservableCollection＆lt; T＆gt;做。

编辑详细信息项时，此视图不允许使用“EditItem”

1 个答案: