Chapter 14: CUSTOMIZING TEMPLATES OF THE LISTVIEW CONTROL

acydburn01 · February 5th, 2018, 07:05 AM

I have followed the book but when I try to add a photo by clicking the insert button. I get an error on the underlined line of code. How can I fix this?

the error I get:
An exception of type 'System.NullReferenceException' occurred in App_Web_fc2yp5zf.dll but was not handled in user code

System.NullReferenceException was unhandled by user code
HResult=-2147467261
Message=Object reference not set to an instance of an object.
Source=App_Web_fc2yp5zf
StackTrace:
at _ManagePhotoAlbum.ListView1_InsertItem(Int32 photoAlbumId) in C:\BegASPNET\PlanetWrox\ManagePhotoAlbum.aspx.vb:l ine 19
InnerException:

Code:

Imports System.Web.ModelBinding

Partial Class _ManagePhotoAlbum
    Inherits BasePage

    Public Function ListView1_GetData(<QueryString("PhotoAlbumId")> photoAlbumId As Integer) As IQueryable
        Dim myEntities As New PlanetWroxEntities()
        Return From p In myEntities.Pictures
               Where p.PhotoAlbumId = photoAlbumId
               Select p
    End Function

    Public Sub ListView1_InsertItem(<QueryString("PhotoAlbumId")> photoAlbumId As Integer)
        Dim picture As New Picture()
        TryUpdateModel(picture)

        Dim FileUpload1 As FileUpload = CType(ListView1.InsertItem.FindControl("FileUpload1"), FileUpload)
        If Not FileUpload1.HasFile OrElse Not FileUpload1.FileName.ToLower().EndsWith(".jpg") Then
            Dim cusValImage As CustomValidator = CType(ListView1.InsertItem.FindControl("cusValImage"), CustomValidator)
            cusValImage.IsValid = False
            ModelState.AddModelError("Invalid file type", cusValImage.ErrorMessage)
        End If

        If ModelState.IsValid AndAlso Page.IsValid Then
            Using myEntities As New PlanetWroxEntities()
                picture.PhotoAlbumId = photoAlbumId

                Dim virtualFolder As String = "~/GigPics/"
                Dim physicalFolder As String = Server.MapPath(virtualFolder)
                Dim fileName As String = Guid.NewGuid().ToString()
                Dim extension As String = System.IO.Path.GetExtension(FileUpload1.FileName)

                FileUpload1.SaveAs(System.IO.Path.Combine(physicalFolder, fileName + extension))
                picture.ImageUrl = virtualFolder + fileName + extension

                myEntities.Pictures.Add(picture)
                myEntities.SaveChanges()
            End Using
        End If
    End Sub


    Public Sub ListView1_DeleteItem(ByVal id As Integer)
        Using myEntities As New PlanetWroxEntities()
            Dim picture = (From p In myEntities.Pictures
                           Where p.Id = id
                           Select p).Single()
            myEntities.Pictures.Remove(picture)
            myEntities.SaveChanges()
        End Using
    End Sub
End Class

Found what was wrong. I forgot to change the ID in step 3.