Ch. 14

papadan · April 26th, 2017, 08:03 PM

Per Chapter 14, page 516 instructions, I have inserted the following code below into the ManagePhotoAlbum code-behind file. I am getting red, squiggly lines under the bold parts of this code.:

Code:

  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)
    If ModelState.IsValid Then
      Using myEntities As New PlanetWroxEntities
        picture.PhotoAlbumId = photoAlbumId
        myEntities.Pictures.Add(picture)
        myEntities.SaveChanges()
      End Using
    End If

  End Sub

These are the following errors:

QueryString: Type 'QueryString' is not defined.
TryUpdateModel: 'TryUpdateModel' is not declared. It may be inaccessible due to its protected level.
ModelState: 'ModelState' is not declared. It may be inaccessible due to its protected level.

When I attempt to run the app, I get the following error:

Quote:

A null value for parameter 'photoAlbumId' of non-nullable type 'System.Int32' for method 'System.Linq.IQueryable ListView1_GetData(Int32)' in '_ManagePhotoAlbum'. An optional parameter must be a reference type or a nullable type.
Description: An unhandled exception occurred during the execution of the current web request. Please review the stack trace for more information about the error and where it originated in the code.

Exception Details: System.InvalidOperationException: A null value for parameter 'photoAlbumId' of non-nullable type 'System.Int32' for method 'System.Linq.IQueryable ListView1_GetData(Int32)' in '_ManagePhotoAlbum'. An optional parameter must be a reference type or a nullable type.

Imar · April 29th, 2017, 04:39 AM

Did you see the following in Step 6 on page 515:

Quote:

Note that you need to add a using/Imports statement for the namespace System.Web.ModelBinding to bring the QueryString attribute into scope. You can either type in this namespace manually at the top of the code file, or you can press Ctrl+. (Ctrl+dot) on the word QueryString in the method definition and pick the namespace from the list that appears.

Hope this helps,

Imar

papadan · April 29th, 2017, 08:59 AM

Dear Imar:

Thanks for the quote from your book, but I already had that in my imports statement.

Imar · April 30th, 2017, 10:40 AM

In that case, can you post the full code for the page?

papadan · April 30th, 2017, 12:06 PM

My code is below. One note that I'm seeing now, didn't catch before - the System.Web.ModelBinding line is getting a message when you hover over it.
The message is - Namespace does not contain any public member or cannot be found. Make sure the imported namespace doesn't contain any aliases.

I'm going to google this, but isn't System.Web.ModelBinding a typical namespace to include?

Here is the code on the code-behind file:

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)
    If ModelState.IsValid Then
      Using myEntities As New PlanetWroxEntities
        picture.PhotoAlbumId = photoAlbumId
        myEntities.Pictures.Add(picture)
        myEntities.SaveChanges()
      End Using
    End If

  End Sub

  Public Sub ListView1_DeleteItem(ByVal id As Integer)

  End Sub

End Class

Here is the code in the source file:

Code:

<%@ Page Title="Manage Photo Album" Language="VB" MasterPageFile="~/MasterPages/Frontend.master" AutoEventWireup="false" CodeFile="ManagePhotoAlbum.aspx.vb" Inherits="_ManagePhotoAlbum" %>

<asp:Content ID="Content1" ContentPlaceHolderID="cpMainContent" Runat="Server">
  <asp:ListView ID="ListView1" runat="server" DataKeyNames="Id" InsertItemPosition="LastItem" 
                  SelectMethod="ListView1_GetData" InsertMethod="ListView1_InsertItem" 
                  DeleteMethod="ListView1_DeleteItem">
    <InsertItemTemplate>
      <li>
        Description: <asp:TextBox ID="Description" runat="server" TextMode="MultiLine" 
                        Text='<%# Bind("Description") %>' /><br />
        ToolTip:  <asp:TextBox ID="ToolTip" runat="server"
                        Text='<%# Bind("ToolTip") %>' /><br />
        ImageUrl: <asp:TextBox ID="ImageUrl" runat="server"
                        Text='<%# Bind("ImageUrl") %>' /><br />
        <asp:Button ID ="InsertButton" runat="server" Text="Insert" CommandName="Insert" />
      </li>
    </InsertItemTemplate>
    <ItemTemplate>
      <li>
        Description: <asp:TextBox ID="Description" runat="server" TextMode="MultiLine" 
                        Text='<%# Eval("Description") %>' /><br />
        ToolTip:  <asp:TextBox ID="ToolTip" runat="server"
                        Text='<%# Eval("ToolTip") %>' /><br />
        ImageUrl: <asp:TextBox ID="ImageUrl" runat="server"
                        Text='<%# Eval("ImageUrl") %>' /><br />
        <asp:Button ID ="DeleteButton" runat="server" Text="Delete" CommandName="Delete" />
      </li>
    </ItemTemplate>
    <LayoutTemplate>
      <ul class="ItemContainer">
        <li runat="server" id="ItemPlaceHolder" />
      </ul>
    </LayoutTemplate>
  </asp:ListView>
</asp:Content>

papadan · April 30th, 2017, 12:18 PM

Okay, my target framework was 4.0 and not 4.5 - not sure how that happened, but I should be good to go now.