Entity Framework 6 EntityDataSource does not call SaveChanges in DbContext

Question

I am developing in an asp.net website project. It does not have a very consistent data layer, so I'm trying to implement the first code entity infrastructure.

I recently discovered that people creating an entity structure have created a new version of EntityDataSource that works with Entity Framework 6.

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

This new data source seems really good and it is updating the database. However, it does not seem to call any methods in my DbContext class.

As part of some basic change tracking requirements, I redefined the DbContext SaveChanges () method and put some code to update the tracking fields on each record (CreatedBy, CreatedDate, ModifiedBy, ModifiedDate). It is strange that when I work directly with DBContect, the SaveChanges () method is called. But when I use this EntityDataSource, it does not call SaveChanges ().

How is the dbsets update described in the Entity Framework EntityDataSource above?

Is there any way to get this EntityDataSource to call the DbContext SaveChanges () method?

Is there an alternative to overriding the DBContext SaveChanges method?

Here is an example of defining the essence of my EntityDataSource entity

<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>

DbContext (). EntityDataSource, SaveChanges(). getter Applicants DBSet . - - !

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

Answer 1

Entity Framework EntityDataSource dbsets?

EntityDataSource ObjectContext, DbContext. SaveChanges() DbContext.

- EntityDataSource DbContext SaveChanges()?

, Updating, EntityDataSourceChangingEventArgs DbContext, . , ( ).

protected void x_Updating(object sender, EntityDataSourceChangingEventArgs e) {
        e.Cancel = true;
        DbContext dbc = new DbContext(e.Context, true);
        new YourDbContext(dbc).SaveChanges();
    }

DBContext SaveChanges?

, . ObjectContext , , (. ). SavingChanges , , SaveChanges DbContext. , ,

Vb.Net, . , , , - Vb. , onContextCreated ( aspx).

. . SavingChanges.

Protected Sub onContextCreated(ByVal sender As Object, ByVal args As EntityDataSourceContextCreatedEventArgs)
   AddHandler args.Context.SavingChanges, AddressOf context_SavingChanges
End Sub

Private Sub context_SavingChanges(ByVal sender As Object, ByVal e As EventArgs)
    Dim context As ObjectContext = TryCast(sender, ObjectContext)

    If context IsNot Nothing Then
        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 As ObjectStateEntry In context.ObjectStateManager.GetObjectStateEntries(EntityState.Added Or EntityState.Modified)
            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
    End If

End Sub

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: http://w3stack.org/question/how-can-i-override-dbcontext-savechanges-when-using-entitydatasource-and-database-generated-model-edmx-ef-5/