Maintaining State of CheckBox while Paging in GridView

The Logic

We are storing the primary keys of the checkboxes that are checked into a List where T = data type of the primary key. This is done at PageIndexChanging before we change the page index and re-bind the GridView. And at RowDataBound we are checking whether the DataKeyName(primary key) of each row is in the List. If present , we mark the CheckBox as checked.

Heres the sample code.

The ASPX

<asp:LinkButton ID="btnSelectAllPage" runat="server" 
            CommandName="SelectAllPage" 
            Text="Select All Pages"
            OnCommand="SelectDeselectAllPages" />|
<asp:LinkButton ID="btnDeselectAllPage" runat="server" 
            CommandName="DeselectAllPage" 
            Text="Deselect All Pages"
            OnCommand="SelectDeselectAllPages" />|
<asp:LinkButton ID="btnSelectAll" runat="server" 
            CommandName="SelectAll" 
            Text="Select Page"
            OnCommand="SelectDeselect" />|
<asp:LinkButton ID="btnDeselectAll" runat="server" 
            CommandName="DeselectAll" 
            Text="Deselect Page"
            OnCommand="SelectDeselect" />

<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 ASPX.CS

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 SelectDeselect(object sender, CommandEventArgs e)
{
    foreach (GridViewRow gvr in gvProducts.Rows)
    {
        CheckBox chkSelect = gvr.FindControl("chkSelect") as CheckBox;
        if (chkSelect != null)
        {
            chkSelect.Checked = e.CommandName.Equals("SelectAll");
        }
    }
}

protected void SelectDeselectAllPages(object sender, CommandEventArgs e)
{
    DataSourceSelectArguments dssa = new DataSourceSelectArguments();
    dssa.AddSupportedCapabilities(DataSourceCapabilities.RetrieveTotalRowCount);
    dssa.RetrieveTotalRowCount = true;
    DataView dv = (DataView)sdsProducts.Select(dssa);
    foreach (DataRow dr in dv.Table.Rows)
    {

        int productID = Convert.ToInt32(dr.ItemArray[0]);//ItemArray[0] cos ProductID is in the first column
        if (e.CommandName.Equals("SelectAllPage") && !this.ProductIDs.Contains(productID))
        {
            this.ProductIDs.Add(productID);
        }
        if (e.CommandName.Equals("DeselectAllPage") && this.ProductIDs.Contains(productID))
        {
            this.ProductIDs.Remove(productID);
        }
    }
    foreach (GridViewRow gvr in gvProducts.Rows)
    {
        CheckBox chkSelect = gvr.FindControl("chkSelect") as CheckBox;
        if (chkSelect != null)
        {
            chkSelect.Checked = e.CommandName.Equals("SelectAllPage");
        }
    }
}

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);
        }
    }
}

As an extra enhancement, we are also giving provision for selecting, deselecting both page and the whole rows in every page also here.

P.S: We are using Northwind Sample DataBase by Microsoft, so if you dont have it download it.

Courtesy: A wonderful post by Ed Bruck at forums.asp.net

Related Posts :