SitePoint Sponsor

User Tag List

Results 1 to 6 of 6
  1. #1
    SitePoint Evangelist Miguel61's Avatar
    Join Date
    Mar 2008
    Posts
    402
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)

    Object reference not set to an instance of an object

    Hello guys and good day, I need your help.

    This is my net code, I've this error in object dr, why?
    Can you help me? Thank you in advance.
    PHP Code:
        protected void BindEmployeeDetails()
        {
            
    myConnectionString.Open();

            
    httpCookie CustInfo Request.Cookies["id"]; 

            
    SQL "SELECT * FROM ";
            
    SQL SQL " tbl ";
            
    SQL SQL " WHERE 1 ";
            
            if (
    CustInfo != null)
            {
                
    SQL SQL " AND id = " Request.Cookies["id"].ToString() + " ;";
            }

            
    OdbcCommand cmd = new OdbcCommand(SQLmyConnectionString);
            
    OdbcDataAdapter da = new OdbcDataAdapter(cmd);
            
    DataSet ds = new DataSet();
            
    da.Fill(ds);
            
    OdbcDataReader dr null;


            if (
    dr.Read())
            {
                if (
    ds.Tables[0].Rows.Count 0)
                {
                    
    gvDetails.DataSource ds;
                    
    gvDetails.DataBind();
                }
                else
                {
                    
    ds.Tables[0].Rows.Add(ds.Tables[0].NewRow());
                    
    gvDetails.DataSource ds;
                    
    gvDetails.DataBind();
                    
    int columncount gvDetails.Rows[0].Cells.Count;
                    
    gvDetails.Rows[0].Cells.Clear();
                    
    gvDetails.Rows[0].Cells.Add(new TableCell());
                    
    gvDetails.Rows[0].Cells[0].ColumnSpan columncount;
                    
    gvDetails.Rows[0].Cells[0].Text "No record found";
                }
            }
            else
            {
                
    Response.Write("No user");
            }

            
    myConnectionString.Close();
        }


    Exception DetailsSystem.NullReferenceExceptionObject reference not set to an instance of an object.

    Source Error:


    Line 43:         OdbcDataReader dr null;
    Line 44:
    Line 45:         if (dr.Read())
    Line 46:         {
    Line 47:             if (ds.Tables[0].Rows.Count 0

  2. #2
    Hosting Team Leader silver trophybronze trophy
    cpradio's Avatar
    Join Date
    Jun 2002
    Location
    Ohio
    Posts
    4,807
    Mentioned
    141 Post(s)
    Tagged
    0 Thread(s)
    Because you set it to null...
    OdbcDataReader dr = null;

    You really want to use your ds variable (as that is the one you are filling).
    Be sure to congratulate xMog on earning April's Member of the Month
    Go ahead and blame me, I still won't lose any sleep over it
    My Blog | My Technical Notes

  3. #3
    SitePoint Evangelist Miguel61's Avatar
    Join Date
    Mar 2008
    Posts
    402
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    thank you for suggestion, but:
    PHP Code:
    Compiler Error MessageCS1061'System.Data.DataSet' does not contain a definition for 'Read' and no extension method 'Read' accepting a first argument of type 'System.Data.DataSet' could be found (are you missing a using directive or an assembly reference?)

    Source Error:
     
    Line 46:         if (ds.Read())
    Line 47:         {
    Line 48:             if (ds.Tables[0].Rows.Count 0

  4. #4
    Hosting Team Leader silver trophybronze trophy
    cpradio's Avatar
    Join Date
    Jun 2002
    Location
    Ohio
    Posts
    4,807
    Mentioned
    141 Post(s)
    Tagged
    0 Thread(s)
    that would be correct, ds does not contain read. A dataset is already populated, so you simply start with your inner IF statement.
    Be sure to congratulate xMog on earning April's Member of the Month
    Go ahead and blame me, I still won't lose any sleep over it
    My Blog | My Technical Notes

  5. #5
    SitePoint Evangelist Miguel61's Avatar
    Join Date
    Mar 2008
    Posts
    402
    Mentioned
    4 Post(s)
    Tagged
    0 Thread(s)
    Quote Originally Posted by cpradio View Post
    that would be correct, ds does not contain read. A dataset is already populated, so you simply start with your inner IF statement.
    Ok, thank you.

    But I need check that the value of the cookie is stored.

    If value of the cookie is valid I show the dataset else warning user not enabled for dataset, for this use read.
    Can you help me?

  6. #6
    Hosting Team Leader silver trophybronze trophy
    cpradio's Avatar
    Join Date
    Jun 2002
    Location
    Ohio
    Posts
    4,807
    Mentioned
    141 Post(s)
    Tagged
    0 Thread(s)
    You will get an empty dataset if the value isn't found.

    think

    if (ds != null && ds.Tables.Count != 0 && ds.Tables[0].Rows.Count != 0)
    Be sure to congratulate xMog on earning April's Member of the Month
    Go ahead and blame me, I still won't lose any sleep over it
    My Blog | My Technical Notes


Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •