Question

我有一个带有gridview的表单，当从GV中选择一个记录时，它调用另一个页面details.aspx，详细信息页面有一个FormView，使用SelectMethod =“GetData”，显示所选id记录的数据，a遵循：

Public Function GetData( ByVal id? As Integer) As Ems_Candidate
            Try
                // store record id in memVar to use it when retreve the image
                strRecNo = id.ToString

                Call LoadCandidateImage()

                Return _db.DbSet_Candidates.Find(id)

            Catch ex As Exception
                ModelState.AddModelError("ModelError", ex.Message.ToString)
                Return 1
            End Try
End Function

在绑定到FormView的数据的同时，我必须在此记录的标签中显示某些数据，但在FormView模型之外，我已将上述方法更新为以下内容：

Public Function GetData( ByVal id? As Integer) As Ems_Candidate
        Try
            // store record id in memVar to use it when retrieve the image
            strRecNo = id.ToString

            Call LoadCandidateImage()

    // Start: new lines added
            Dim objQuery As IQueryable(Of Ems_Candidate) = _
                From c In _db.DbSet_Candidates
                Where c.CandidateID = id
                Select c

            For Each c In objQuery
                If c.CandidateStatus.Equals("A") Then
                    Me.lblCandidateStatus.Text = "Active"
                ElseIf c.CandidateStatus.Equals("D") Then
                    Me.lblCandidateStatus.Text = "Deleted"
                ElseIf c.CandidateStatus.Equals("W") Then
                    Me.lblCandidateStatus.Text = "Waived"
                Else
                    Me.lblCandidateStatus.Text = "N/A"
                End If
            Next

    // End: new lines added

            Return _db.DbSet_Candidates.Find(id)

        Catch ex As Exception
            ModelState.AddModelError("ModelError", ex.Message.ToString)
            Return 1
        End Try
End Function

我必须再次查询数据库为IQueryable，才能在返回数据之前选择所需的数据。

我不认为这种方式在同一个地方打两次数据库是切实可行的，即使我不使用Ado.Net也不会这样做，有没有办法增强代码？

感谢您的帮助。

Answer 1

将查询结果放入临时变量中，如此

Public Function GetData(ByVal id? As Integer) As Ems_Candidate
    Try
        // store record id in memVar to use it when retreve the image
        strRecNo = id.ToString

        Call LoadCandidateImage()

        Dim result As Ems_Candidate
        result = _db.DbSet_Candidates.Find(id)

        Select Case result.CandidateStatus
            Case "A"
                Me.lblCandidateStatus.Text = "Active"
            Case "D"
                Me.lblCandidateStatus.Text = "Deleted"
            Case "W"
                Me.lblCandidateStatus.Text = "Waived"
            Case Else
                Me.lblCandidateStatus.Text = "N/A"
        End Select

        Return result

    Catch ex As Exception
        ModelState.AddModelError("ModelError", ex.Message.ToString)
        Return 1
    End Try
End Function

如何增强此代码（LINQ to Entity）

1 个答案: