object reference not set to an instance of an object.[Answered] RSS

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  rkoravi

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  object reference not set to an instance of an object.

  Nov 29, 2012 10:05 AM|rkoravi|LINK

  protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
      {
          int Eid = Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Value);
          System.Web.UI.WebControls.TextBox name = (System.Web.UI.WebControls.TextBox)GridView1.Rows[e.RowIndex].FindControl("FName");
          System.Web.UI.WebControls.TextBox address = (System.Web.UI.WebControls.TextBox)GridView1.Rows[e.RowIndex].FindControl("LName");
          System.Web.UI.WebControls.TextBox designation = (System.Web.UI.WebControls.TextBox)GridView1.Rows[e.RowIndex].FindControl("txtEmail");
          string ename = name.Text;
          string eaddress = address.Text;
          string edesignation = designation.Text;
          con.Open();
          SqlCommand cmd = new SqlCommand("Update Regis Set FName='"+ename+"',LName='"+eaddress+"',Email='"+edesignation+"' where Sno='"+Eid+"'", con);
          cmd.ExecuteNonQuery();
          con.Close();
          GridView1.EditIndex = -1;
                 
          GrBind();
      }

  Hi i didnt know where mistake pls anyone help me...

  i need row updating in gridview asp.net c#...Thank you

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  bbcompent1

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 10:15 AM|bbcompent1|LINK

  My suggestion to you is set a breakpoint at int Eid and step through the code using the debugger. watch the values because this error means you have a null value.

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  oned_gk

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 10:23 AM|oned_gk|LINK

  you have not define con
  Programming to simplify, don't look for difficult way
  Suwandi - Non Graduate Programmer
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  rkoravi

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 10:24 AM|rkoravi|LINK

  Hi, no null value in database y the error occur

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  msmk

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 10:26 AM|msmk|LINK

  Your update statement should look like this:

  "Update Regis Set FName='+"ename"+',LName='+"eaddress"+',Email='+"edesignation"+' where Sno='+"Eid"+'"

  (I moved over the + symbols).

  You should probably be using parameters though. This is not the safest way to pass in values to sql query

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  rkoravi

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 11:11 AM|rkoravi|LINK

  Hi frinds,

  Its worked but no changes when update anyone can help me

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  msmk

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 11:19 AM|msmk|LINK

  Nevermind, set your query back to the way you had it originally. I was thinking of ename, eaddress etc as strings but they are variables. Sorry about that

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  bbcompent1

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 11:22 AM|bbcompent1|LINK

  You didn't define what con is, your connection object. Should be something like:

  SqlConnection con = new SqlConnection(yourconnstring);

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  rkoravi

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 11:30 AM|rkoravi|LINK

  Hi bbcompent1  ,

  ya (ie) sql connection string

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  bbcompent1

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 11:32 AM|bbcompent1|LINK

  But you haven't declared it as an actual SqlConnection object. It doens't know what it is. Just try it the way I'm telling you to. I have over 10 years experience in dot net development. Another user also mentioned this as well.

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  bbcompent1

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 11:35 AM|bbcompent1|LINK

  You have your cmd right however you dont' have an actual connection strin in the code you show above. This is what I usually do:

  SqlConnection conn2 = new SqlConnection(myconnectionstring);
          string killtable = "TRUNCATE TABLE MyTable;";
          SqlCommand cmd2 = new SqlCommand(killtable, conn2);
          conn2.Open();
          cmd2.ExecuteNonQuery();
          conn2.Close();

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  RameshRajend...

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 12:18 PM|RameshRajendran|LINK

  Hai

  Please check your Eid value...and Also verify that you have assign DataKey in gridview

  
  

  But i think The gridview rowupdating event was not fired.Please check this thread

  http://forums.asp.net/t/1800251.aspx/1

  
  

  Thank you...

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  bbcompent1

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 12:44 PM|bbcompent1|LINK

  He's doing all this in code behind, his data in the gridview shows fine, he isn't able to write to the database. I told him to set break points and step through to make sure his events are actually firing. So far, he hasn't responded so I have to presume he's working on it.

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  RameshRajend...

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 01:12 PM|RameshRajendran|LINK

  bbcompent1

  He's doing all this in code behind, his data in the gridview shows fine, he isn't able to write to the database. I told him to set break points and step through to make sure his events are actually firing. So far, he hasn't responded so I have to presume he's working on it.

  Ya.Sorry i not saw your answers ..but i think your last code is wrong.because that he was used  in this line con.Open .So i think  that he commanly used the  sqlconnection and call need a time.But Why this code not updating?

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  RameshRajend...

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 01:32 PM|RameshRajendran|LINK

  Hey guy

  Check this sample code

  protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
  {
      GridViewRow row = (GridViewRow)GridView1.Rows[e.RowIndex];
      int id = Int32.Parse(GridView1.DataKeys[e.RowIndex].Value.ToString());
      TextBox tname = (TextBox)row.FindControl("nam");
      TextBox tques = (TextBox)row.FindControl("que");
      MySqlCommand cmd = new MySqlCommand("update exam set name1=@name,ques=@ques where id = @id", con);
      cmd.Parameters.Add("@id", MySqlDbType.Int16).Value = id;
      cmd.Parameters.Add("@name", MySqlDbType.VarChar, 30).Value = tname.Text.Trim();
      cmd.Parameters.Add("@ques", MySqlDbType.VarChar,40).Value = tques.Text.Trim();
      con.Open();
      cmd.ExecuteNonQuery();
      GridView1.EditIndex = -1;
      bind();
  }

  Good luck buddy.........

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  RameshRajend...

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 01:38 PM|RameshRajendran|LINK

  msmk

  Nevermind, set your query back to the way you had it originally. I was thinking of ename, eaddress etc as strings but they are variables. Sorry about that

  Good listen buddy...............But Your query is working properly with just change where Sno='+"1"+'"

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  oned_gk

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  Re: object reference not set to an instance of an object.

  Nov 29, 2012 09:00 PM|oned_gk|LINK

  Before

  con.Open();

  Declare con inside this event.

  Programming to simplify, don't look for difficult way
  Suwandi - Non Graduate Programmer
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  bbcompent1

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  Re: object reference not set to an instance of an object.

  Nov 30, 2012 06:45 AM|bbcompent1|LINK

  oned_gk

  Before

  con.Open();

  Declare con inside this event.

  Precisely, this is what we have been telling the OP since page one.

  Mark as answer posts that helped you.
  
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  CommDev

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  Re: object reference not set to an instance of an object.

  Dec 03, 2012 08:43 PM|CommDev|LINK

  Hi rkoravi,

  From your code, I have another suggestion that you should add “try … catch …” to avoid the “conn” is not closed properly. 

  protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
      {
          int Eid = Convert.ToInt32(GridView1.DataKeys[e.RowIndex].Value);
          System.Web.UI.WebControls.TextBox name = (System.Web.UI.WebControls.TextBox)GridView1.Rows[e.RowIndex].FindControl("FName");
          System.Web.UI.WebControls.TextBox address = (System.Web.UI.WebControls.TextBox)GridView1.Rows[e.RowIndex].FindControl("LName");
          System.Web.UI.WebControls.TextBox designation = (System.Web.UI.WebControls.TextBox)GridView1.Rows[e.RowIndex].FindControl("txtEmail");
          string ename = name.Text;
          string eaddress = address.Text;
          string edesignation = designation.Text;
  
  	    SqlConnection con = new SqlConnection(yourconnstring);
  	    try
  	    {
                  con.Open();
          	SqlCommand cmd = new SqlCommand("Update Regis Set FName='"+ename+"',LName='"+eaddress+"',Email='"+edesignation+"' where Sno='"+Eid+"'", con);
          	cmd.ExecuteNonQuery();
  	    }
  	    catch(Exception)
  	    {
  		    throw;
  	    }
              finally
  	    {
  		    con.Close();
  	    }
  
          GridView1.EditIndex = -1;
                 
          GrBind();
      }

  
  
  

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