About the Session showing the error mess Object reference not set to an instance of an object.

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Sir,

My default page is Site.master page & i have written the code in my Site.Master is bellow:
====================

C#

protected void Page_Load(object sender, EventArgs e)
       {

           if (!String.IsNullOrEmpty(Session["userName"].ToString()))
           ////if (Session["UserName"] != null)
           {

           lblUName.Text = "Welcome" + Session["userName"].ToString();

           //    //lnkLogout.Visible=true;
           }
           else
           {
               Response.Redirect("Login.aspx");
           }

           }

===============

Ans i also write the code in my Login.aspx.cs page is bellow for Session..
===============

C#

if (result >= 1)
           {
               Session["userName"] = txtUserName.Text.ToString().Trim();
               Response.Redirect("Site.master");
           }
           else
               lblMsg.Text = "Incorrect Username or Password";

==============

Now when i run the program it shown the error mess bellow::

Object reference not set to an instance of an object.

please help me where is my mistake???

Posted 14-Apr-13 19:42pm

prodipjsr

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amperayani 15-Apr-13 1:48am

write like this

if(session["username"]!=null)

prodipjsr 15-Apr-13 1:56am

Whine i use ur code it shown the error mess::
The page isn't redirecting properly

5 solutions

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vishal.shimpi · Answer 1 · 2013-04-14T19:52:00

Solution 1

Try the If condition like, because .ToString() method cant handle null value

if (!String.IsNullOrEmpty(Convert.ToString(Session["userName"])))
{
  // your code
}

Posted 14-Apr-13 19:52pm

vishal.shimpi

_Amy · Answer 2 · 2013-04-14T19:54:00

string.IsNullOrEmpty[^] tests strings. It checks for string references that are null, or empty strings. Strings are reference types and can be equal to null like any other reference type.
It is equivalent to result = SomeString == null || SomeString == String.Empty.

Since your code

Quote:
if (!String.IsNullOrEmpty(Session["userName"].ToString()))

Here you are already converting the Session["userName"] to string using ToString() function. In this case if the session is null it'll give NullReferanceException, because a null value cannot converted to string.

Try this:

C#

if (Session["UserName"] != null)
{
    string s = "Welcome" + Session["userName"].ToString();
    //    //lnkLogout.Visible=true;
}
else
{
    Response.Redirect("Login.aspx");
}

--Amit

snehal harawande · Answer 3 · 2013-04-14T19:58:00

Solution 3

amperayani is correct use if(session["username"]!=null) in master.

Why u r redirecting to master page from login page?
You should redirect to .aspx page.

Posted 14-Apr-13 19:58pm

snehal harawande

Comments

prodipjsr 15-Apr-13 2:26am

please let me clear what the meaning of redirect.aspx page??? i cant understand where i should write what??? please give me a code with example..

HTML-CSS · Answer 4 · 2013-04-14T20:03:00

Solution 4

C#

qryUserName = "SELECT user_name,password FROM Login WHERE user_name ='" + username + "' AND password ='" + Password+ "'";
SqlCommand cmd = new SqlCommand(qryUserName, con);
string CurrentName;
AuthenticationName = (string)cmd.ExecuteScalar();
if (AuthenticationName != null)
{
Session["Authentication"] = username;
Session.Timeout = 1;
Response.Redirect("site.aspx");
}
else
{
Session["Authentication"] = "";
}

Try To Redirect on .aspx not on .Master

Posted 14-Apr-13 20:03pm

HTML-CSS

Comments

prodipjsr 15-Apr-13 2:26am

please let me clear what the meaning of redirect.aspx page??? i cant understand where i should write what??? please give me a code with example..

HTML-CSS 15-Apr-13 3:19am

Its Simple Bro..

Download this demo

https://www.dropbox.com/s/4xul8wpcbpdeooe/672Login.rar

Just Look code There is No DB so may bee you cant Login

Abhinav S · Answer 5 · 2013-04-14T20:07:00

Solution 5

This error occurs when you are trying to access an attribute of an object when the object itself is null.
Debugging your code will help you understand where the error occurs.

Posted 14-Apr-13 20:07pm

Abhinav S

Comments

prodipjsr 15-Apr-13 2:27am

i cant understand where i should write what??? please give me a code with example..

About the Session showing the error mess Object reference not set to an instance of an object.

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