Populate DropDownList with Selected Value in EditItemTemplate of GridView in ASP.Net

In this article I will explain with an example how to use ASP.Net DropDownList control in the EditItemTemplate of ASP.Net GridView control.

I created this GridView with EditItemTemplate.

        <asp:GridView ID="GridView1" runat="server" AllowPaging="True" AllowSorting="True"
            AutoGenerateColumns="False" AutoGenerateEditButton="True" DataKeyNames="CodeAction"
            OnRowEditing="GridView1_RowEditing" OnRowDataBound="GridView1_RowDataBound" OnRowUpdating="GridView1_RowUpdating"
            OnPageIndexChanging="GridView1_PageIndexChanging" OnRowCancelingEdit="GridView1_RowCancelingEdit">
            <Columns>
                <asp:CommandField ShowSelectButton="True" />
                <asp:BoundField DataField="CodeAction" HeaderText="CodeAction" ReadOnly="True" SortExpression="CodeAction" />
                <asp:BoundField DataField="Description" HeaderText="Description" SortExpression="Description" />
                <asp:TemplateField HeaderText="Group" SortExpression="GroupID">
                    <EditItemTemplate>
                        <asp:Label ID="Label1" runat="server" Text='<%# Eval("GroupID") %>' Visible="false"></asp:Label>
                        <asp:DropDownList ID="ddlGroup" runat="server" DataTextField="Group" DataValueField="IDGroup"
                            AutoPostBack="True" OnSelectedIndexChanged="ddlGroup_SelectedIndexChanged">
                        </asp:DropDownList>
                    </EditItemTemplate>
                    <ItemTemplate>
                        <asp:Label ID="Label1" runat="server" Text='<%# Eval("GroupID") %>'></asp:Label>
                    </ItemTemplate>
                </asp:TemplateField>
                <asp:TemplateField HeaderText="Subgroup" SortExpression="SubGroupID">
                    <EditItemTemplate>
                        <asp:Label ID="Label2" runat="server" Text='<%# Eval("SubGroupID") %>' Visible="false"></asp:Label>
                        <asp:DropDownList ID="ddlSubgroup" runat="server" DataTextField="Group" DataValueField="IDGroup">
                        </asp:DropDownList>
                    </EditItemTemplate>
                    <ItemTemplate>
                        <asp:Label ID="Label2" runat="server" Text='<%# Eval("SubGroupID") %>'></asp:Label>
                    </ItemTemplate>
                </asp:TemplateField>
            </Columns>
        </asp:GridView>

The code behide is this:

        CnnString cnn = new CnnString();
        public reportGroup rg = new reportGroup();

        private void LoadData()
        {
            Schema.DataClassesDataContext pdc = new Schema.DataClassesDataContext(cnn.getString());
            Schema.tbl_BalanceGroup bg = new Schema.tbl_BalanceGroup();
            var qry = from g in pdc.tbl_BalanceGroups orderby g.Description select g;
            this.GridView1.DataSource = qry.ToList(); this.GridView1.DataBind();
        }

        protected void Page_Load(object sender, EventArgs e)
        {
            if (!Page.IsPostBack)
            {
                LoadData();
            }
        }

        protected void ddlGroup_SelectedIndexChanged(object sender, EventArgs e)
        {
            DropDownList ddlSub = (DropDownList)this.GridView1.Rows[this.GridView1.EditIndex].FindControl("ddlSubgroup");
            if (ddlSub != null)
            {
                DropDownList ddlGroup = (DropDownList)this.GridView1.Rows[this.GridView1.EditIndex].FindControl("ddlGroup");
                ddlSub.DataSource = rg.ListOfGroup(ddlGroup.SelectedValue, "");
                ddlSub.DataBind();
            }
        }

        protected void GridView1_RowEditing(object sender, GridViewEditEventArgs e)
        {
            GridView1.EditIndex = e.NewEditIndex; LoadData();
        }

        protected void GridView1_RowDataBound(object sender, GridViewRowEventArgs e)
        {
            if (e.Row.RowType == DataControlRowType.DataRow && GridView1.EditIndex == e.Row.RowIndex)
            {
                reportGroup rg = new reportGroup();
                DropDownList ddlGroup = (DropDownList)e.Row.FindControl("ddlGroup");
                ddlGroup.Items.Clear();
                ddlGroup.AppendDataBoundItems = true;
                ddlGroup.DataSource = rg.ListOfGroup("", "");
                ddlGroup.DataBind(); ddlGroup.Items.Add("");
                Label lbl = (Label)e.Row.FindControl("Label1");

                if (lbl != null)
                {
                    ddlGroup.SelectedValue = lbl.Text;
                    DropDownList ddlSub = (DropDownList)e.Row.FindControl("ddlSubgroup");
                    if (ddlSub != null)
                    {
                        ddlSub.Items.Clear();
                        if (lbl.Text != "")
                        {
                            ddlSub.AppendDataBoundItems = true;
                            ddlSub.DataSource = rg.ListOfGroup(lbl.Text, "");
                            ddlSub.DataBind(); ddlSub.Items.Add("");
                            Label lbl2 = (Label)e.Row.FindControl("Label2");
                            if (lbl != null)
                            {
                                ddlSub.SelectedValue = lbl2.Text;
                            }
                        }
                    }
                }
            }
            else
            {
                Label lbl = (Label)e.Row.FindControl("Label1");
                if (lbl != null)
                {
                    lbl.Text = rg.Name(lbl.Text);
                }
                Label lbl1 = (Label)e.Row.FindControl("Label2");
                if (lbl1 != null)
                {
                    lbl1.Text = rg.Name(lbl1.Text);
                }
            }
        }

        protected void GridView1_RowUpdating(object sender, GridViewUpdateEventArgs e)
        {
            String CodeID = GridView1.DataKeys[e.RowIndex].Value.ToString();
            GridViewRow row = GridView1.Rows[e.RowIndex];
            Schema.DataClassesDataContext pdc = new Schema.DataClassesDataContext(cnn.getString());
            Schema.tbl_BalanceGroup bg = new Schema.tbl_BalanceGroup();
            var qry = from g in pdc.tbl_BalanceGroups where g.CodeAction == CodeID select g;
            if (qry.Count() > 0)
            {
                bg = qry.First(); bg.GroupID = new Guid(((DropDownList)row.FindControl("ddlGroup")).SelectedValue.ToString());
                DropDownList ddl = (DropDownList)row.FindControl("ddlSubgroup");
                if (ddl != null)
                {
                    if (ddl.SelectedValue != "")
                    {
                        bg.SubGroupID = new Guid(ddl.SelectedValue.ToString());
                    }
                    else
                    {
                        bg.SubGroupID = Guid.Empty;
                    }
                }
                pdc.SubmitChanges();
            }
            pdc.Connection.Close();
            this.GridView1.EditIndex = -1;
            LoadData();
        }

        protected void GridView1_RowCancelingEdit(object sender, GridViewCancelEditEventArgs e)
        {
            this.GridView1.EditIndex = -1; LoadData();
        }

        protected void GridView1_PageIndexChanging(object sender, GridViewPageEventArgs e)
        {
            LoadData();
            GridView1.PageIndex = e.NewPageIndex; GridView1.DataBind();
        }