adding check box dynamically to gridview

Question

<asp:GridView ID="SearchGrid" runat="server" GridLines="Both" AutoGenerateColumns="false">
                        <Columns>
                            <asp:BoundField DataField="Q" HeaderText="Q" />
                            <asp:TemplateField HeaderText="C">
                                <ItemTemplate>
                                    <asp:CheckBox ID="CCheckbox" runat="server" AutoPostBack="true" OnCheckedChanged="CCheckbox_CheckedChanged" />
                                </ItemTemplate>
                            </asp:TemplateField>
                             <asp:TemplateField HeaderText="R">
                                <ItemTemplate>
                                    <asp:CheckBox ID="RCheckbox" runat="server" AutoPostBack="true" OnCheckedChanged="RCheckbox_CheckedChanged" />
                                </ItemTemplate>
                            </asp:TemplateField>
                             <asp:TemplateField HeaderText="E">
                                <ItemTemplate>
                                    <asp:CheckBox ID="ECheckbox" runat="server" AutoPostBack="true" OnCheckedChanged="ECheckbox_CheckedChanged" />
                                </ItemTemplate>
                            </asp:TemplateField>
                        </Columns>
                    </asp:GridView>

This is my Aspx code for the GridView

if (ViewState["SearchGrid"] == null)
            {
                SearchTable.Columns.Add(new DataColumn("Q", typeof(string)));
                SearchTable.Columns.Add(new DataColumn("C", typeof(bool)));
                SearchTable.Columns.Add(new DataColumn("R", typeof(bool)));
                SearchTable.Columns.Add(new DataColumn("E", typeof(bool)));
                ViewState["SearchGrid"] = SearchTable;
            }
            SearchTable =(DataTable) ViewState["SearchGrid"];
            DataRow dr = null;
            dr = SearchTable.NewRow();
            dr["Q"] = MySearchTextBox.Text;
            switch (SearchType)
            {
                case "Contains": dr["C"] =true;
                    break;
                case "Related": dr["R"] = true;
                    break;
                case "Exact": dr["E"] = true;
                    break;
            }

and my code behind.

At the time of adding the row I have to check a paticular check box. I have been trying to check the checkbox by giving its values as true but it does not seem to work. Can someone tell me what I am doing wrong here?

Answer 1

You can bind in the markup to the value: Checked='<%# Eval("C") %>'

<asp:GridView ID="SearchGrid" runat="server" GridLines="Both" AutoGenerateColumns="false">
    <Columns>
        <asp:BoundField DataField="Q" HeaderText="Q" />
        <asp:TemplateField HeaderText="C">
            <ItemTemplate>
                <asp:CheckBox ID="CCheckbox" runat="server" AutoPostBack="true" OnCheckedChanged="CCheckbox_CheckedChanged" Checked='<%# Eval("C") %>' />
            </ItemTemplate>
        </asp:TemplateField>
            <asp:TemplateField HeaderText="R">
            <ItemTemplate>
                <asp:CheckBox ID="RCheckbox" runat="server" AutoPostBack="true" OnCheckedChanged="RCheckbox_CheckedChanged" Checked='<%# Eval("E") %>' />
            </ItemTemplate>
        </asp:TemplateField>
            <asp:TemplateField HeaderText="E">
            <ItemTemplate>
                <asp:CheckBox ID="ECheckbox" runat="server" AutoPostBack="true" OnCheckedChanged="ECheckbox_CheckedChanged" Checked='<%# Eval("R") %>' />
            </ItemTemplate>
        </asp:TemplateField>
    </Columns>
</asp:GridView>

Or you can use rowdatabound event: OnRowDataBound="SearchGrid_RowDataBound"

MarkUP Change:

<asp:GridView ID="SearchGrid" runat="server" GridLines="Both" AutoGenerateColumns="false" OnRowDataBound="SearchGrid_RowDataBound">

Codebehind: Note i used a list object instead of a datatable.

public class TestObject
{
    public string Q { get; set; }
    public bool C { get; set; }
    public bool R { get; set; }
    public bool E { get; set; }
}
public partial class Default : System.Web.UI.Page
{
    public List<TestObject> Values { get; set; }
    protected void Page_Load(object sender, EventArgs e)
    {
        if (!Page.IsPostBack)
        {
            //NEED SOME DATA TO TEST THE RESULT
            Values = new List<TestObject>();

            Values.Add(new TestObject() { Q = "test 1", C = true, E = true, R = true });
            Values.Add(new TestObject() { Q = "test 1", C = true, E = false, R = true });
            Values.Add(new TestObject() { Q = "test 1", C = true, E = true, R = false });
            Values.Add(new TestObject() { Q = "test 1", C = false, E = true, R = true });
            //BIND TO THE GRID
            SearchGrid.DataSource = Values;
            SearchGrid.DataBind();
        }
    }

    //FIRES FOR EVERY ROW IN THE GRID
    protected void SearchGrid_RowDataBound(object sender, GridViewRowEventArgs e)
    {
        //WE ONLY CARE ABOUT THE DATAROW NOT HEADER ETC
        if (e.Row.RowType != DataControlRowType.DataRow)
            return;
        //GET THE BOUND INDIVIDUAL ITEM
        TestObject obj = (TestObject)e.Row.DataItem; //IN YOUR CASE THIS WOULD BE: DataRow row = (DataRow)e.Row.DataItem

        //FIND ALL THE CHECKBOXES
        CheckBox cchk = e.Row.FindControl("CCheckBox") as CheckBox;
        CheckBox echk = e.Row.FindControl("ECheckBox") as CheckBox;
        CheckBox rchk = e.Row.FindControl("RCheckBox") as CheckBox;

        //CHECK IT OR NOT BASED ON THE DATATITEMS VALUE
        if (cchk != null)
            cchk.Checked = obj.C; //IN YOUR CASE THIS WOULD BE: bool c = (bool)row["C"];

        if (echk != null)
            echk.Checked = obj.E;

        if (rchk != null)
            rchk.Checked = obj.R;
    }
}

Answer 2

You can try to check out the functionality of GridView.RowDataBound. Use this event to capture the row when it has data bound to it and then you should be able to access the CheckBox item and assign its .Checked value.

Link: http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.gridview.rowdatabound.aspx