Select all Gridview record using CheckBox in the Gridview header

Question

I am using checkbox in the gridview header to select all records in the gridview. this is the code behind method.

<asp:GridView ID="gvP" runat="server" AutoGenerateColumns="false" AllowPaging="false"
AllowSorting="false" DataKeyNames="PmtId" CssClass="list-table" HeaderStyle-CssClass="header"
EnableModelValidation="True">
    <Columns>
    <asp:BoundField DataField="PmtId" HeaderText="PmtId" ReadOnly="True" Visible="false" />
    <asp:TemplateField HeaderText="All" ItemStyle-CssClass="checkbox-col" HeaderStyle-CssClass="checkbox-col">
    <HeaderStyle HorizontalAlign="Center" />
    <HeaderTemplate>
    <input id="chkBoxAll" type="checkbox" onclick='javascript:checkAllBoxes("CLEAR_PT")' />
    </HeaderTemplate>
    <ItemTemplate>
    <asp:CheckBox runat="server" ID="chkSelect" />
    </ItemTemplate>
    </asp:TemplateField>
    <asp:TemplateField HeaderText="S/No." ItemStyle-CssClass="seq-col" HeaderStyle-CssClass="seq-col">
    <ItemTemplate>
    <%# Eval("SNo")%>
    </ItemTemplate>
    </asp:TemplateField>
    </Columns>
</asp:GridView> 

protected void chkSelectAll(string arg)
{
    if (arg.Equals("CLEAR_PT"))
    {
    CheckBox chkAll = gvP.HeaderRow.FindControl("chkBoxAll") as CheckBox;
    if (chkAll.Checked == true)
    {
    foreach (GridViewRow gvRow in gvP.Rows)
    {
    CheckBox chkSel = (CheckBox)gvRow.FindControl("chkSelect") as CheckBox;
    chkSel.Checked = true;
    }
    }
    else
    {
    foreach (GridViewRow gvRow in gvP.Rows)
    {
    CheckBox chkSel = (CheckBox)gvRow.FindControl("chkSelect") as CheckBox;
    chkSel.Checked = false;
    }
    }
    }
}

I am getting 'Object reference not set to an instance of an object' run time error in the following line.

if (chkAll.Checked == true)

Any Idea?

Could you provide your gridview aspx code?

Thit Lwin Oo
– Thit Lwin Oo

2012-02-27 02:40:55 +00:00
Commented Feb 27, 2012 at 2:40 — Thit Lwin Oo
– Thit Lwin Oo, Commented Feb 27, 2012 at 2:40
Updated above. please check now.

vml19
– vml19

2012-02-27 02:45:46 +00:00
Commented Feb 27, 2012 at 2:45 — vml19
– vml19, Commented Feb 27, 2012 at 2:45

Thit Lwin Oo · Accepted Answer · 2012-02-27 02:52:51Z

1

Your checkbox control in header template is html input control. You need to change as ASP.NET check box control. Change as server checkbox control and try. Actually check all and uncheck all can be done in client side javascript. No need postback.

answered Feb 27, 2012 at 2:52

Thit Lwin Oo

3,4283 gold badges22 silver badges23 bronze badges

Sign up to request clarification or add additional context in comments.

Collectives™ on Stack Overflow

Select all Gridview record using CheckBox in the Gridview header

1 Answer 1

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

1 Answer 1

Comments

Your Answer

Sign up or log in

Post as a guest

Related