Object reference not set to an instance of an object.

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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.

C#

Exception Details: System.NullReferenceException: Object reference not set to an instance of an object.

This is my code.

C#

private void bindimage()
{
    
    SqlDataAdapter adp = new SqlDataAdapter("select  image from display where username=@us", con);
   adp.SelectCommand.Parameters.AddWithValue("@us", Session["ss"].ToString());
   // SqlDataAdapter ado = new SqlDataAdapter();
  // adp.SelectCommand = new SqlCommand("select  image from display where username='@us'", con);
 //  adp.SelectCommand = new SqlCommand();
    //adp.SelectCommand.Parameters.AddWithValue("@us",(Session["ss"]).ToString());
    DataSet ds = new DataSet();
    adp.Fill(ds);
    DataList2.DataSource = ds;
    DataList2.DataBind();
}

The error comes from this line as follow:

C#

Error line: adp.SelectCommand.Parameters.AddWithValue("@us", Session["ss"].ToString());

Posted 1-Jun-13 19:08pm

dps2305

Updated 1-Jun-13 20:43pm

Tadit Dash (ତଡିତ୍ କୁମାର ଦାଶ)

v2

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Comments

Hitesh_Mistry 2-Jun-13 1:18am

have you checked the value in the session variable..???

Swayam231 2-Jun-13 4:17am

well replace addwith to add and write this
("@us", sqldbtype.varchar).value= session["ss"].tostring

Let me know if it heps

2 solutions

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_Amy · Answer 1 · 2013-06-02T18:12:00

Before using any session variable you should check for it's existence. If that session is NULL then definitely it'll show Null Reference Exception. Try this:

C#

private void bindimage()
{    
    if(Session["ss"] != null){
        SqlDataAdapter adp = new SqlDataAdapter("select  image from display where username=@us", con);
        adp.SelectCommand.Parameters.AddWithValue("@us", Session["ss"].ToString());
        DataSet ds = new DataSet();
        adp.Fill(ds);
        DataList2.DataSource = ds;
        DataList2.DataBind();
    }
    else{
        Response.Write("Session is null"); // You can remove this and show any kind of message to user.
    }
}

--Amit

Pankaj.Sinha.Techno · Answer 2 · 2013-06-01T19:25:00

Solution 1

It seems the "ss" does not have any value in Session. Everything else looks fine.

Posted 1-Jun-13 19:25pm

Pankaj.Sinha.Techno

Comments

[no name] 2-Jun-13 2:03am

no i have n't check ss.how to fix this error.Please suggest me.

Pankaj.Sinha.Techno 2-Jun-13 2:13am

Since while addding parameter to command you are fetching a value from session using string index "ss". Please make sure that this value is being added into session before that.

replcae line
adp.SelectCommand.Parameters.AddWithValue("@us", Session["ss"].ToString());
with
if (Session["ss"] != null)
{
adp.SelectCommand.Parameters.AddWithValue("@us", Session["ss"].ToString());
}

and also since you are the one who is responsible to add this value into session in the code make sure you are doing that.

[no name] 2-Jun-13 2:43am

Thank you so much for your suggestion But an another error come with a message
Must declare scalar variable "us".what can i do for this?Please help me

Calvijn 2-Jun-13 10:53am

It says that your variable "@us" in "SqlDataAdapter adp = new SqlDataAdapter("select image from display where username=@us", con);"

is not declared.
Something like "DECLARE @us VARCHAR(128)"
also you have to set a value for that variable like:
"SET @us = 'WHAT EVER YOU SET'