How to get the value dynamically created checkbox value in asp.net gridview

Question

I'm adding checkbox controls dynamically in asp.net gridview like this:

CheckBox cb1 = new CheckBox();
cb1.Text = row.Cells[3].Text;
row.Cells[3].Controls.Add(cb1);

And I want to access whether that checkbox is checked or not on button click event...

on button click I have tried this:

foreach (GridViewRow item in grdreport.Rows)
{
    if (item.RowType == DataControlRowType.DataRow)
    {
        CheckBox checkbox1 = (CheckBox)item.FindControl("cb1");
        // cb1.Checked = true;
        if (checkbox1.Checked)
        {
        }
    }
}

but it gives me an error:

Object reference not set to an instance of an object cb1 value is null

Hi @Nivas. When you run your program , right click on page and look at source , or use similar tool to do so. You will be able to verify what name your control actually has. — Alicia, Jan 23 '19 at 10:57

SomethingCool · Answer 1 · 2019-01-23T11:21:37.337

0

foreach (GridViewRow row in grdreport.Rows)
{

    CheckBox checkbox1= (row.Cells[3].FindControl("cb1") as CheckBox);
    if (checkbox1.Checked)
                        {

                        }
}

There is a need to access the checkbox trough a specific row and cell

edited Jan 23 '19 at 11:21

answered Jan 23 '19 at 11:01

SomethingCool

303
2
20

still same error 'Object reference not set to an instance of an object.' – Nivas Khatal Jan 23 '19 at 11:40
'foreach (GridViewRow row in grdreport.Rows) { CheckBox checkbox1 = (row.Cells[3].FindControl("cb1") as CheckBox); // cb1.Checked = true; if (checkbox1.Checked) { } }'. – Nivas Khatal Jan 23 '19 at 11:40
@NivasKhatal When are you adding the check boxes, on poageload? – SomethingCool Jan 23 '19 at 13:21
No i dont add it on page load – Nivas Khatal Jan 24 '19 at 04:50
Object reference not set to an instance of an object cb1 value is null – Nivas Khatal Jan 28 '19 at 05:40
do the check boxes exist before the button click event when do you add them to your page? @NivasKhatal – SomethingCool Jan 28 '19 at 09:56
yes checkbox exist before button click and i am adding them on rowdatabound event – Nivas Khatal Jan 29 '19 at 09:13

score 0 · Answer 2 · answered Jan 23 '19 at 12:54

0

Focus on this line:

 CheckBox checkbox1 = (CheckBox)item.FindControl("cb1");

First check if item.FindControl("cb1") is giving you any value or not. More Info - Object Reference Exception

answered Jan 23 '19 at 12:54

Sahil Sharma

1,813
1
16
37

cb1 is giviing null value – Nivas Khatal Jan 24 '19 at 05:02
still same error 'Object reference not set to an instance of an object.' – Nivas Khatal Jan 28 '19 at 05:34

score 0 · Answer 3 · answered Jul 19 '20 at 21:46

When checkbox or any object is added dynamically to Gridview during RowDataBound(), and if the value of that dynamic object should be retrieved on button click, enable view state for that object during RowDataBound() and it works like a charm.

CheckBox cb1 = new CheckBox();
cb1.Text = row.Cells[3].Text;
**cb1.EnableViewState = true;**
row.Cells[3].Controls.Add(cb1);

How to get the value dynamically created checkbox value in asp.net gridview

3 Answers3