Question

I have used the paging in the gridview.
I need the code for check/uncheck in gridview either in server side or client side.
I have tried without paging, it’s working. I need it with paging.

<asp:TemplateField>
<HeaderTemplate>
<asp:CheckBox ID="chkHGrid" runat="server" />
</HeaderTemplate>
<ItemTemplate>
<asp:CheckBox ID="chkGrid" runat="server" />
</ItemTemplate>
<ItemStyle HorizontalAlign="Center" />
<HeaderStyle HorizontalAlign="Center" />
</asp:TemplateField>

Answer 1

This technique is called maintaining the state of GridView CheckBox in Paging. One method to achieve this is as follows.

1. Create a Genric List of int or string to store the DataKeys related to Checked rows in it.
2. At PageIndexChanging before you set the PageIndex to new index. For each rows in GridView,
   • If checkbox is checked, store the id to the generic list.
   • If checkbox is unchecked & the ID exist in generic list, remove it from the list.
3. At RowDataBound event, for each DataRow, check if the DataKeyName is present in the Generic List. If so, find the CheckBox and make it checked.

A simple example with Products Table, Northwind Database is given below

The Markup

<asp:GridView ID="gvProducts" runat="server"
            AllowPaging="True"
            AutoGenerateColumns="False"
            DataKeyNames="ProductID"
            OnPageIndexChanging="gvProducts_PageIndexChanging"
            OnRowDataBound="gvProducts_RowDataBound">
    <Columns>
        <asp:TemplateField HeaderText="Select">
            <ItemTemplate>
                <asp:CheckBox ID="chkSelect" runat="server" />
            </ItemTemplate>
        </asp:TemplateField>
    <asp:BoundField DataField="ProductID" HeaderText="ProductID" InsertVisible="False"
    ReadOnly="True" SortExpression="ProductID" />
    <asp:BoundField DataField="ProductName" HeaderText="ProductName" SortExpression="ProductName" />
    </Columns>
</asp:GridView>
<asp:SqlDataSource ID="sdsProducts" runat="server"
                ConnectionString='<%$ ConnectionStrings:NorthwindConnectionString %>'
                SelectCommand="SELECT * FROM Products">
</asp:SqlDataSource>

The Code Behind

private List<int> ProductIDs
{
    get
    {
        if (this.ViewState["ProductIDs"] == null)
        {
            this.ViewState["ProductIDs"] = new List<int>();
        }
        return this.ViewState["ProductIDs"] as List<int>;
    }
}

protected void gvProducts_PageIndexChanging(object sender, GridViewPageEventArgs e)
{
    foreach (GridViewRow gvr in gvProducts.Rows)
    {
        CheckBox chkSelect = gvr.FindControl("chkSelect") as CheckBox;
        if (chkSelect != null)
        {
            int productID = Convert.ToInt32(gvProducts.DataKeys[gvr.RowIndex]["ProductID"]);
            if (chkSelect.Checked && !this.ProductIDs.Contains(productID))
            {
                this.ProductIDs.Add(productID);
            }
            else if (!chkSelect.Checked && this.ProductIDs.Contains(productID))
            {
                this.ProductIDs.Remove(productID);
            }
        }
    }
}

protected void gvProducts_RowDataBound(object sender, GridViewRowEventArgs e)
{
    GridViewRow gvr = e.Row;
    if (gvr.RowType == DataControlRowType.DataRow)
    {
        CheckBox chkSelect = gvr.FindControl("chkSelect") as CheckBox;
        if (chkSelect != null)
        {
            int productID = Convert.ToInt32(gvProducts.DataKeys[gvr.RowIndex]["ProductID"]);
            chkSelect.Checked = this.ProductIDs.Contains(productID);
        }
    }
}