Question

我的ObservableCollection终于提取了数据，但现在它没有保存编辑。

这是我的代码：

public void FillDataGrid(Guid corporationId)
{
    var query = from s in entity.Sources
                where s.CorporationId == corporationId
                select new SourceItem
                {
                    CorporationId = s.CorporationId,
                    Description = s.Description,
                    IsActive = s.IsActive,
                    Name = s.Name,
                    SourceId = s.SourceId,
                    TokenId = s.TokenId
                };

    SoureItemCollection = new ObservableCollection<SourceItem>(query);
    SourceDataGrid.ItemsSource = SoureItemCollection;
    SourceDataGrid.Columns[2].Visibility = Visibility.Hidden;
    SourceDataGrid.Columns[0].IsReadOnly = true;
    SourceDataGrid.Columns[1].IsReadOnly = true;
}

这是我要绑定的类：

public class SourceItem
{
    private Guid _corporationId1;
    private string _description;
    private bool _isActive;
    private string _name;
    private Guid _sourceId;
    private Guid _tokenId;

    public Guid CorporationId
    {
        set
        {
            _corporationId1 = value;
            onPropertyChanged(this, "CorporationId");
        }
        get { return _corporationId1; }
    }

    public string Description
    {
        set
        {
            _description = value;
            onPropertyChanged(this, "Description");
        }
        get { return _description; }
    }

    public bool IsActive
    {
        set
        {
            _isActive = value;
            onPropertyChanged(this, "IsActive");
        }
        get { return _isActive; }
    }

    public string Name
    {
        set
        {
            _name = value;
            onPropertyChanged(this, "NAme");
        }
        get { return _name; }
    }

    public Guid SourceId
    {
        set
        {
            _sourceId = value;
            onPropertyChanged(this, "SourceId");
        }
        get { return _sourceId; }
    }

    public Guid TokenId
    {
        set
        {
            _tokenId = value;
            onPropertyChanged(this, "TokenId");
        }
        get { return _tokenId; }
    }

    // Declare the PropertyChanged event
    public event PropertyChangedEventHandler PropertyChanged;

    // OnPropertyChanged will raise the PropertyChanged event passing the
    // source property that is being updated.
    private void onPropertyChanged(object sender, string propertyName)
    {
        if (PropertyChanged != null)
        {
            PropertyChanged(sender, new PropertyChangedEventArgs(propertyName));
        }
    }
}

保存：

private void Save_Click(object sender, RoutedEventArgs e)
{
    entity.SaveChanges();
}

我想在保存之前将ObservableCollection绑定回实体吗？如果是这样，我该怎么做？

Answer 1

您已创建数据副本，并且您正在编辑该副本。实体框架上下文完全没有意识到这一点。

您可以使用实体数据对象，而不是使用SourceItem中的字段。例如：

var query = from s in entity.Sources
            where s.CorporationId == corporationId
            select new SourceItem(s);

class SourceItem
{
  private SourceEntity _model;

  public SourceItem(SourceEntity model)
  {
      _model = model;
  }

  public Guid CorporationId
  {
    get { return _mode.CorporationId; }
    set
    {
      _model.CorporationId = value;
      OnPropertyChanged(this, "CorporationId");
    }
  }
}

请注意，这与ObservableCollection无关。如果要添加或删除集合中的项目，则还需要将其同步到实体模型。您可以使用CollectionChanged事件。

Answer 2

看到的问题是表达式“var query = from s in entity.Sources .. select new SourceItem {..} ”你没有检索附加到上下文的实体（实体）但是您已经创建了SourceItem类型的新对象，这些对象无法映射回数据库实体。你应该做的是你应该更改你的SourceItem类，它直接由entity.Sources对象支持（我猜它应该是它的构造函数参数）。将SourceItem字段委托回相应的Sources字段（双向）。因此，SourceItem将封装Sources对象并使用所有WPF内容装饰它以进行MVVM操作。

ObservableCollection编辑未保存

2 个答案: