Grid Sort Using List & Linq Concepts

<asp:GridView ID="gvResults" runat="server" AutoGenerateColumns="false" CssClass="list"

GridLines="None" AllowSorting="True" OnSorting="gv_Sorting" meta:resourcekey="gvResultsResource1"

OnRowDataBound="gvResults_RowDataBound" AllowPaging="false">

<Columns>

<asp:BoundField HeaderText="No" DataField="id" SortExpression="id" HeaderStyle-CssClass="center">

<HeaderStyle CssClass="center" />

</asp:BoundField>

<asp:TemplateField SortExpression="priority" meta:resourcekey="TemplateFieldResource1">

<ItemTemplate>

<div class="color_it" style="background: <%# urgency[Int32.Parse(Eval("priority").ToString())] %>">

 <%# Eval("priority1.priority_name") %></div>

</ItemTemplate><HeaderStyle Width="60px"></HeaderStyle>

</asp:TemplateField>

<asp:TemplateField SortExpression="title" meta:resourcekey="TemplateFieldResource2">

<ItemTemplate>

</ItemTemplate>

<HeaderStyle Width="380px"></HeaderStyle>

</asp:TemplateField>

<asp:TemplateField HeaderText="SubGroup" SortExpression="SubGroup">

<ItemTemplate>

<asp:Label ID="lblSubGroupbyId" Visible="false" Text='<%# Eval("assigned_to_group") %>' runat="server"></asp:Label>

<asp:Label ID="lblSubGroupby" runat="server"></asp:Label>

</ItemTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="AssignedTo" SortExpression="Assign_To">

<ItemTemplate>

<asp:Label ID="lblAssignedbyId" Visible="false" Text='<%# Eval("Assign_To") %>' runat="server"></asp:Label>

<asp:Label ID="lblAssignedby" runat="server"></asp:Label>

</ItemTemplate>

</asp:TemplateField>

<asp:BoundField DataField="ExpectedDate" SortExpression="ExpectedDate" DataFormatString="{0:d}"

HtmlEncode="False" HeaderText="Expected Date">

<HeaderStyle Width="120px" />

<ItemStyle HorizontalAlign="Center" />

</asp:BoundField>

<asp:TemplateField HeaderText="Raisedby" SortExpression="Ticket_rasied">

<ItemTemplate>

<asp:Label ID="lblRaisedbyId" Visible="false" Text='<%# Eval("Ticket_rasied") %>' runat="server"></asp:Label>

<asp:Label ID="lblRaisedBy" runat="server"></asp:Label>

</ItemTemplate>

</asp:TemplateField>

<asp:TemplateField HeaderText="Center" SortExpression="Center">

<ItemTemplate>

<%# GetCenterName(Convert.ToInt32(Eval("Center")))%>

</ItemTemplate> </asp:TemplateField>

<asp:BoundField DataField="submitted" SortExpression="submitted" DataFormatString="{0:d}" HtmlEncode="False" meta:resourcekey="BoundFieldResource1">

<HeaderStyle Width="80px" />

<ItemStyle HorizontalAlign="Center" /> </asp:BoundField>

<asp:TemplateField SortExpression="status" meta:resourcekey="TemplateFieldResource3">

<ItemTemplate>

<div class="color_it" style="width: 83px; text-align: center;">

<%# Eval("statuse.status_name") %></div> </ItemTemplate>

<HeaderStyle CssClass="center" HorizontalAlign="Center" />

</asp:TemplateField>

</Columns>

</asp:GridView>

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protected void gv_Sorting(object sender, GridViewSortEventArgs e)

    {

IEnumerable<ticket> searchResults = IEnumerable<ticket>)Session["searchResults"];

GridView gv = (GridView)sender;

if (Session[e.SortExpression] == null || Session[e.SortExpression].ToString().Equals("+"))

{

Session[e.SortExpression] = "-";

switch (e.SortExpression)

{

case "priority": searchResults = from p in searchResults orderby p.priority1.level ascending select p; break;

case "title": searchResults = from p in searchResults orderby p.title ascending select p; break;

case "submitted": searchResults = from p in searchResults orderby p.submitted ascending select p; break;                case "status": searchResults = from p in searchResults join s in db.statuses on p.ticket_status equals s.id orderby s.status_name ascending select p; break;

case "Assign_To": searchResults = from p in searchResults join u in db.users on p.Assign_To equals u.id orderby u.userName ascending select p; break;

case "Ticket_rasied": searchResults = from p in searchResults join u in db.users on p.Ticket_rasied equals u.id orderby u.userName ascending select p; break;

case "id": searchResults = from p in searchResults orderby p.id ascending select p; break;

case "Center": searchResults = from p in searchResults join c in db.Centers on p.Center equals c.id orderby c.Center_name ascending select p; break;

case "ExpectedDate": searchResults = from p in searchResults orderby p.ExpectedDate ascending select p; break;

case "SubGroup": searchResults = from p in searchResults orderby p.assigned_to_group ascending select p; break;

default: break;

}

}

else

{

Session[e.SortExpression] = "+";

switch (e.SortExpression)

{

case "priority": searchResults = from p in searchResults orderby p.priority1.level descending select p; break;                case "title": searchResults = from p in searchResults orderby p.title descending select p; break;

case "submitted": searchResults = from p in searchResults orderby p.submitted descending select p; break;                case "status": searchResults = from p in searchResults join s in db.statuses on p.ticket_status equals s.id orderby s.status_name descending select p; break;

case "Assign_To": searchResults = from p in searchResults join u in db.users on p.Assign_To equals u.id orderby u.userName descending select p; break;

case "Ticket_rasied": searchResults = from p in searchResults join u in db.users on p.Ticket_rasied equals u.id orderby u.userName descending select p; break;

case "id": searchResults = from p in searchResults orderby p.id descending select p; break;

case "Center": searchResults = from p in searchResults join c in db.Centers on p.Center equals c.id orderby c.Center_name descending select p; break;

case "ExpectedDate": searchResults = from p in searchResults orderby p.ExpectedDate descending select p; break;

case "SubGroup": searchResults = from p in searchResults orderby p.assigned_to_group descending select p; break;

default: break;

}

}

gv.DataSource = searchResults;

gv.DataBind();

}