error :Object reference not set to an instance of an object. please HELP

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3.00/5 (2 votes)

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Server Error in '/' Application.
Object reference not set to an instance of an object.
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.NullReferenceException: Object reference not set to an instance of an object.
 Source Error: 

Line 7:      protected void Page_Load(object sender, EventArgs e)
Line 8:      {
Line 9:          string strCat = Request.QueryString["Category"].ToString() 
Line 10:         string strBook = Request.QueryString["Book"].ToString() 
Line 11:         string strConn = ConfigurationManager.ConnectionStrings["BookStoreDBConnectionString1"].ToString() 
Source File: c:\Users\Asmaa\Documents\Visual Studio 2010\Projects\BOOKSTORE\BOOKSTORE\BooksDetails.aspx    Line: 9

Posted 25-May-11 9:27am

Basma.r

Updated 25-May-11 17:05pm

thatraja

v2

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3 solutions

Solution 2

Instead of .ToString()

U can use Convert.ToString as it handles null values like

C++

Convert.ToString(Request.QueryString["Category"]);

Posted 25-May-11 18:15pm

Ashishmau

Solution 3

simply try this

string strCat = Request.QueryString["Category"];
           string strBook = Request.QueryString["Book"];
           string strConn =  ConfigurationManager.ConnectionStrings["BookStoreDBConnectionString1"]!=null? ConfigurationManager.ConnectionStrings["BookStoreDBConnectionString1"].ToString(): string.Empty;

Posted 25-May-11 18:34pm

Shahdat Hosain

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Jpuckett · Accepted Answer · 2011-05-25T09:30:00

Solution 1

Request.QueryString["Category"] is null.

Do a null check first.

if(Request.QueryString["Category"] != null) 
{
     strCat = Request.QueryString["Category"].ToString()
}

and continue with that pattern.

Posted 25-May-11 9:30am

Jpuckett

Updated 25-May-11 17:06pm

v2

Comments

Sergey Alexandrovich Kryukov 25-May-11 15:31pm

Bug detected. A 5.
--SA