Hello Imaar,
Please can you help me with correcting this error on Chapter 14 - 'Object reference not set to an instance of an object'.
I tried to run the NewPhotoAlbum.aspx page and click 'Insert', but was greeted with that error message. I have tried everything to rectify the error but it still doesn't give.
Please help me out as I am really enjoying this your book and insightful gaining knowledge. I don't want to get deterred.
Below are the codes for both pages (NewPhotoAlbum and ManagePhotoAlbum):
ManagePhotoAlbum
Code:
<%@ Page Title="Manage Photo Album" Language="C#" MasterPageFile="~/MasterPages/Frontend.master" AutoEventWireup="true" CodeFile="ManagePhotoAlbum.aspx.cs" Inherits="_ManagePhotoAlbum" %>
<asp:Content ID="Content1" ContentPlaceHolderID="head" runat="Server">
</asp:Content>
<asp:Content ID="Content2" ContentPlaceHolderID="cpMainContent" runat="Server">
<asp:ListView ID="ListView1" runat="server" DataKeyNames="Id" DataSourceID="EntityDataSource1" InsertItemPosition="LastItem" OnItemInserting="ListView1_ItemInserting">
<InsertItemTemplate>
<li style="">Description:
<asp:RequiredFieldValidator ID="reqDesc" ControlToValidate="DescriptionTextBox" runat="server" ErrorMessage="Enter a description." />
<asp:TextBox ID="DescriptionTextBox" runat="server" Text='<%# Bind("Description") %>' TextMode="MultiLine" />
<br />
ToolTip:
<asp:RequiredFieldValidator ID="reqTooltip" ControlToValidate="ToolTipTextBox" runat="server" ErrorMessage="Enter a tool tip." />
<asp:TextBox ID="ToolTipTextBox" runat="server" Text='<%# Bind("ToolTip") %>' />
<br />
<asp:FileUpload ID="FileUpload1" runat="server" /><br />
<asp:CustomValidator ID="cusValImage" ErrorMessage="Select a valid .jpg file." runat="server" />
<br />
<asp:Button ID="InsertButton" runat="server" CommandName="Insert" Text="Insert" />
<asp:Button ID="CancelButton" runat="server" CommandName="Cancel" Text="Clear" CausesValidation="False" />
</li>
</InsertItemTemplate>
<ItemTemplate>
<li style="">Description:
<asp:Label ID="DescriptionLabel" runat="server" Text='<%# Eval("Description") %>' />
<br />
ToolTip:
<asp:Label ID="ToolTipLabel" runat="server" Text='<%# Eval("ToolTip") %>' />
<br />
<asp:Image ID="ImageUrl" runat="server" ImageUrl='<%# Eval("ImageUrl") %>' />
<br />
<asp:Button ID="DeleteButton" runat="server" CommandName="Delete" Text="Delete" CausesValidation="False" />
</li>
</ItemTemplate>
<LayoutTemplate>
<ul class="ItemContainer">
<li runat="server" id="itemPlaceholder" />
</ul>
</LayoutTemplate>
</asp:ListView>
<asp:EntityDataSource ID="EntityDataSource1" runat="server" ConnectionString="name=PlanetWroxEntities" DefaultContainerName="PlanetWroxEntities" EnableDelete="True" EnableFlattening="False" EnableInsert="True" EntitySetName="Pictures" Where="it.PhotoAlbum.Id = @photoAlbumId" OnInserting="EntityDataSource1_Inserting">
<WhereParameters>
<asp:QueryStringParameter Name="PhotoAlbumId" QueryStringField="PhotoAlbumId" Type="Int32" />
</WhereParameters>
</asp:EntityDataSource>
</asp:Content>
NewPhotoAlbum (CS file)
Code:
using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using PlanetWroxModel;
public partial class _NewPhotoAlbum : BasePage
{
protected void Page_Load(object sender, EventArgs e)
{
}
protected void EntityDataSource1_Inserted(object sender, EntityDataSourceChangedEventArgs e)
{
PhotoAlbum myPhotoAlbum = (PhotoAlbum) e.Entity;
Response.Redirect(string.Format("ManagePhotoAlbum.aspx?PhotoAlbumId={0} ", myPhotoAlbum.Id.ToString()));
}
}
Thank you.
Tobi
PLEASE HELP WITH THE ERROR IN Chapter 14 LINQ and the ADO.NET Entity Framework
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