Question

我原来的问题是here。

以下是我的更新代码。

Public Function StockTransferItemRemove(removeRequest As StockTransferItemRequest) As StockTransferItemResponse Implements IStockTransferService.StockTransferItemRemove
        ' create your objects
        Dim removeResponse = New StockTransferItemResponse
        Dim stockTransfer As New StockTransfer
        Dim stockTransferItem As New StockTransferItem

        Try

            ' get the aggregate root
            stockTransfer = _stockTransferRepository.FindBy(removeRequest.StockTransferID).FirstOrDefault

            stockTransfer.RemoveItem(removeRequest.StockTransferItemView.Id)

            _stockTransferRepository.Save(stockTransfer)

            Dim count As Integer = _uow.WMSCommit()

            If (count > 0) Then
               ' the object was saved succesfully
                    removeResponse.Success = True
            Else
               ' the object was not saved successfully
               removeResponse.BrokenRules.Add(New BusinessRule(String.Empty, String.Empty, Tags.Messages.Commit_Failed))
            End If


        Catch ex As Exception
            ' an unexpected error occured
            removeResponse.BrokenRules.Add(New BusinessRule(String.Empty, String.Empty, ex.Message))
        End Try

        Return removeResponse
    End Function

当工作单元尝试提交时，会产生以下错误消息。

The operation failed: The relationship could not be changed because one or more of 
the foreign-key properties is non-nullable. When a change is made to a relationship,
the related foreign-key property is set to a null value. If the foreign-key does not 
support null values, a new relationship must be defined, the foreign-key property must 
be assigned another non-null value, or the unrelated object must be deleted.

我知道当我使用StockTransfer.RemoveItem（）时，它会从集合中删除该项，但它会将记录保存在数据库中，这就是我收到错误的原因。

有没有办法从聚合Root中删除子对象并持久保存聚合根？

Answer 1

我很抱歉代码不清楚，但我是一个C＃家伙，所以试图找到我的方式在VB代码。您应该在要清除的实体链接上使用.Clear（）选项。

示例：

公司＆lt;＆gt;员工

Company.Emplyees.Clear（）删除关系中的所有记录   表

Answer 2

这也是一个问题。我不知道纯粹的解决方案，但我总是必须在保存更改之前在ef上下文中手动删除它。在用于保存的存储库方法中您应该检查ef上下文中但不在聚合集合中的实体，并从上下文中的dbset中删除它们。

Answer 3

你找到了一个好的解决方案吗？我使用ParentAttribute创建了一个解决方案，并扩展了DbContext SaveChanges或ValidateEntity。您可以找到我的解决方案here。

Answer 4

答案可能有点晚了但是，我的数据上下文中的这个扩展方法DataContext（继承自DbContext）使用EF4.3为我工作。

public static void Delete<TEntity>(this DataContext context, IEnumerable<TEntity> entities) where TEntity : class, new()
{
    foreach (var entity in entities)
    {
        context.Delete(entity);
    }
}

public static void Delete<TEntity>(this DataContext context, TEntity entity) where TEntity : class, new()
{
    var obj = context.Entry(entity);
    if (obj.State == System.Data.EntityState.Detached)
    {
        context.Set(typeof(TEntity)).Attach(obj.Entity);
    }
    context.Set(typeof(TEntity)).Remove(obj.Entity);
}

数据上下文类只是为了完整性。

public class DataContext : DbContext
{
    public DbSet<MyPOCO> POCOs { get; set; }

    ...
}

使用EF存储库从聚合根删除子对象

4 个答案: