entity-framework - 实体框架：保存对象？

Question

这是我的代码：

Partial Public Class AppsEntities
Private Sub OnContextCreated()
    AddHandler Me.SavingChanges, AddressOf context_SavingChanges
End Sub
Private Shared Sub context_SavingChanges(ByVal sender As Object, ByVal e As EventArgs)
    For Each entry As ObjectStateEntry In DirectCast(sender, ObjectContext).ObjectStateManager.GetObjectStateEntries(EntityState.Modified)
        If Not entry.IsRelationship And entry.Entity IsNot Nothing Then
            For Each propName As String In entry.GetModifiedProperties()
                Dim audit As New History
                audit.action = "Changed information in " & propName & " to " & entry.CurrentValues(propName) & " from " & entry.OriginalValues(propName)
                audit.action_by = "dmackey"
                audit.action_date = Date.Now
                audit.extension_id = entry.CurrentValues.GetValue(1)
            Next

        End If


    Next
End Sub

结束类

如何保存我创建的这个新对象？在 LINQ 中，我会做类似的事情：

datasource.object.insertonsubmit(audit)
datasource.SubmitChanges()

Answer 1

这是我的最终代码：

Partial Public Class AppsEntities
Private Sub OnContextCreated()
    AddHandler Me.SavingChanges, AddressOf context_SavingChanges
End Sub
Private Shared Sub context_SavingChanges(ByVal sender As Object, ByVal e As EventArgs)
    For Each entry As ObjectStateEntry In DirectCast(sender, ObjectContext).ObjectStateManager.GetObjectStateEntries(EntityState.Modified)
        If Not entry.IsRelationship And entry.Entity IsNot Nothing Then
            For Each propName As String In entry.GetModifiedProperties()
                Dim context As New AppsEntities()
                Dim audit As New History
                audit.action_note = "Changed information in " & propName & " to " & entry.CurrentValues(propName) & " from " & entry.OriginalValues(propName)
                audit.action_by = "dmackey"
                audit.action_date = Date.Now
                audit.extension_id = entry.CurrentValues.GetValue(0)
                context.AddToHistories(audit)
                context.SaveChanges()
            Next

        End If

    Next
End Sub

End Class

本质上，我必须做的是：

• 在我的 ForEach 中定义一个新的 AppsEntities 实例（“上下文”），
• 然后我必须将审计对象添加到当前 AppEntities（“上下文”）中的历史记录中。
• 最后，我必须告诉上下文（“AppsEntities”）以将更改保存到数据库（停止仅将其保存在 EF 云中）。