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Textbox disappers due to post back and showed Error:Object reference not set to an in

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Join Date: Apr 2007

Posts: 15

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pen2satya

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Textbox disappers due to post back and showed Error:Object reference not set to an in

Jun 9th, 2009

I have a Gridview having 3 columns in which i took checkbox,label and label as item templates for columns select,code,name respectively.
ecode column is not editable.Button edit and update are present outside of gridview.

i can edit multiple rows like this...

when i select checkbox in 1st row of gridview then in ename column of that row i added textbox by this code

 Help with Code Tags 
 ASP.NET Syntax (Toggle Plain Text) 
 protected void btnEdit_Click(object sender, EventArgs e)
    {
 
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            txteditEname = new TextBox();       
            CheckBox chkDelete = (CheckBox)GridView1.Rows[i].Cells[0].FindControl("chkSelect");
            Label lblEname = (Label)GridView1.Rows[i].Cells[0].FindControl("lblEname");
 
            if (chkDelete.Checked)
            {
                GridView1.Rows[i].Cells[2].Controls.Add(txteditEname);
                txteditEname.Text = lblEname.Text;
                lblEname.Visible = false;
            }
 
        }
    }
 
protected void btnUpdate_Click(object sender, EventArgs e)
    {
        ArrayList al = new ArrayList();
 
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
 
            CheckBox chkDelete = (CheckBox)GridView1.Rows[i].Cells[0].FindControl("chkSelect");
            txteditEname = (TextBox)GridView1.Rows[i].Cells[2].FindControl("txteditEname");
            string str=txteditEname.Text;//error
 protected void btnEdit_Click(object sender, EventArgs e)
    {
        
        for (int i = 0; i < GridView1.Rows.Count; i++)
        {
            txteditEname = new TextBox();       
            CheckBox chkDelete = (CheckBox)GridView1.Rows[i].Cells[0].FindControl("chkSelect");
            Label lblEname = (Label)GridView1.Rows[i].Cells[0].FindControl("lblEname");
           
            if (chkDelete.Checked)
            {
                GridView1.Rows[i].Cells[2].Controls.Add(txteditEname);
                txteditEname.Text = lblEname.Text;
                lblEname.Visible = false;
            }

        }
    }

protected void btnUpdate_Click(object sender, EventArgs e)
    {
        ArrayList al = new ArrayList();

        for (int i = 0; i < GridView1.Rows.Count; i++)
        {

            CheckBox chkDelete = (CheckBox)GridView1.Rows[i].Cells[0].FindControl("chkSelect");
            txteditEname = (TextBox)GridView1.Rows[i].Cells[2].FindControl("txteditEname");
            string str=txteditEname.Text;//error

//here i set breakpoint and wanted to retrieve txteditEname but error comes...
then thinking that there is no such textbox when i press Update button as autopost back then
i saved the txteditEname 's value in Viewstate but when i retrieved viewstate it showed me the textbox's value before page is posted back.
But the current txteditEname's value is different which i want to update.Please tell me how to get curret txteditEname's value.
But before that i wonder if this textbox is not available then i'll surely get null value.

Last edited by peter_budo; Jun 9th, 2009 at 10:10 am. Reason: Keep It Organized - For easy readability, always wrap programming code within posts in [code] (code blocks) and [icode] (inline code) tags.

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Join Date: Oct 2008

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adatapost

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Posting Maven

Re: Textbox disappers due to post back and showed Error:Object reference not set to an in

Jun 9th, 2009

Please refer the ASP.NET Page life cycle topic at MSDN. ASP.NET page and control objects are created on each post back.

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Join Date: May 2008

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dnanetwork dnanetwork is offline

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Re: Textbox disappers due to post back and showed Error:Object reference not set to a

Jun 27th, 2009

your code will never work..

you need to iterate through Gridview rows..

Checking should be done on RowDataBound Event..

 Help with Code Tags 
 ASP.NET Syntax (Toggle Plain Text) 
foreach(GridviewRows Gvr in Gridview1.rows)
{
  Checkbox chk = (CheckBox)e.row.FindControl("Name Of Your Checkbox");
 
if(chk.checked == true)
{
 // carry out rest of the operation...
}
}
foreach(GridviewRows Gvr in Gridview1.rows)
{
  Checkbox chk = (CheckBox)e.row.FindControl("Name Of Your Checkbox");

if(chk.checked == true)
{
 // carry out rest of the operation...
}
}

Last edited by peter_budo; Jun 27th, 2009 at 11:37 am. Reason: Keep It Organized - For easy readability, always wrap programming code within posts in [code] (code blocks) and [icode] (inline code) tags.