实体框架6 EntityDataSource不在DbContext中调用SaveChanges

我正在开发一个asp.net网站项目 . 它没有非常一致的数据层，所以我试图实现代码第一实体框架 .

我最近发现创建实体框架的人已经创建了一个与Entity Framework 6一起使用的新版EntityDataSource .

http://blogs.msdn.com/b/webdev/archive/2014/02/28/announcing-the-release-of-dynamic-data-provider-and-entitydatasource-control-for-entity-framework-6.aspx

这个新的数据源似乎非常好，它更新了数据库 . 它似乎没有调用我的DbContext类上的任何方法 .

作为一些基本的变更跟踪要求的一部分，我已经重写了DbContext SaveChanges（）方法并将一些代码放入更新每条记录（CreatedBy，CreatedDate，ModifiedBy，ModifiedDate）的跟踪字段 . 奇怪的是，当我直接使用DBContect时，会调用SaveChanges（）方法 . 但是当我使用这个EntityDataSource时，它不会调用SaveChanges（） .

How does the Entity Framework EntityDataSource above go about updating the dbsets?

Is there any way I can make this EntityDataSource call the DbContext SaveChanges() method?

Is there an alternative to overriding the DBContext SaveChanges Method?

这是我的实体框架EntityDataSource控件定义的一个示例

<asp:ListView ID="FormView" runat="server" DataKeyNames="RecordId" DataSourceID="ApplicantDataSource" DefaultMode="Edit">
    <EditItemTemplate>
        <asp:TextBox runat="server" ID="SomeField" Text='<%# Bind("SomeField")%>' ></asp:TextBox>
    </EditItemTemplate>
</asp:ListView>

<ef:EntityDataSource runat="server" 
                     ID="ApplicantDataSource"
                     ContextTypeName="Organisation.Application.MyDbContext"
                     EntitySetName="Applicants"
                     Where="it.RecordId=@RecordId"
                     EnableUpdate="true">
    <WhereParameters>
        <asp:QueryStringParameter Name="RecordId" QueryStringField="RecordId" DbType="String" DefaultValue=""/>
    </WhereParameters>
</ef:EntityDataSource>

这是我的DbContext（减少） . 在EntityDataSource上调用update时，它不会通过SaveChanges（） . 它甚至没有调用Applicants属性中的getter来访问申请人的DBSet . 它仍然设法以某种方式保存信息！

Public Class MyDbContext
    Inherits DbContext

    Public Shared Sub MyDbContext()
        Database.SetInitializer(Of MyDbContext)(Nothing)
    End Sub

    Public Sub New()
        MyBase.New("Name=ConnectionString")
    End Sub

    Public Property Applicants() As DbSet(Of Applicant)

    Protected Overrides Sub OnModelCreating(modelBuilder As DbModelBuilder)

        modelBuilder.Conventions.Remove(Of PluralizingTableNameConvention)()

        MyBase.OnModelCreating(modelBuilder)
    End Sub

    Public Overrides Function SaveChanges() As Integer
        Try
            Dim entities = Me.ChangeTracker.Entries().Where(Function(x) TypeOf x.Entity Is MyBase AndAlso (x.State = EntityState.Added OrElse x.State = EntityState.Modified))
            Dim currentUsername As String

            If HttpContext.Current IsNot Nothing And HttpContext.Current.User IsNot Nothing Then
                currentUsername = HttpContext.Current.User.Identity.Name
            Else
                currentUsername = "System"
            End If

            For Each entity In entities
                If entity.State = EntityState.Added Then
                    DirectCast(entity.Entity, MyBase).CreatedDate = DateTime.Now
                    DirectCast(entity.Entity, MyBase).CreatedBy = currentUsername
                ElseIf entity.State = EntityState.Modified Then
                    entity.Property("CreatedBy").IsModified = False
                    entity.Property("CreatedDate").IsModified = False
                End If

                DirectCast(entity.Entity, MyBase).ModifiedDate = DateTime.Now
                DirectCast(entity.Entity, MyBase).ModifiedBy = currentUsername
            Next

            Return MyBase.SaveChanges()
        Catch ex As DbEntityValidationException
            ' Retrieve the error messages as a list of strings.
            Dim errorMessages = ex.EntityValidationErrors.SelectMany(Function(x) x.ValidationErrors).[Select](Function(x) x.ErrorMessage)

            ' Join the list to a single string.
            Dim fullErrorMessage = String.Join("; ", errorMessages)

            ' Combine the original exception message with the new one.
            Dim exceptionMessage = String.Concat(ex.Message, " The validation errors are: ", fullErrorMessage)

            ' Throw a new DbEntityValidationException with the improved exception message.
            Throw New DbEntityValidationException(exceptionMessage, ex.EntityValidationErrors)
        End Try
    End Function

End Class