How to Group By Razor view by Month - asp.net-mvc

Question

Im using MVC razor view
How do I group by my index view basen on Month in TrDate ??
My Index Controller:
private InvoiceMasterEntities db = new InvoiceMasterEntities();
public ActionResult Index(int compID, string searchBy, string search, int? page, string sortBy)
{
ViewBag.SortDateParam = string.IsNullOrEmpty(sortBy) ? "Date desc" : "";
ViewBag.SortStatusParam = sortBy == "Status" ? "Status desc" : "Status";
var detail = db.DetailPengirimen.AsQueryable();
if (searchBy == "CustID")
{
detail = detail.Where(b => b.CustID.Contains(search) || search == null);
}
else
{
detail = detail.Where(a => a.Customer.Fullname.Contains(search) || search == null);
}
detail = detail.Where(a => a.CompID == compID);
switch (sortBy)
{
case "Date desc":
detail = detail.OrderByDescending(a => a.TrDate);
break;
case "Status desc":
detail = detail.OrderByDescending(a => a.Status.Status1);
break;
case "Status":
detail = detail.OrderBy(a => a.Status.Status1);
break;
default:
detail = detail.OrderBy(a => a.TrDate);
break;
}
return View(detail.ToPagedList(page ?? 1, 10));
}
My Index View:
#using PagedList;
#using PagedList.Mvc;
#model IPagedList<InvoiceTracker.Models.DetailPengiriman>
<h2>Couriers List</h2>
<p>
#Html.ActionLink("Insert Data", "Create", new { compID = Request.QueryString["compID"] })
</p>
<p>
#using (Html.BeginForm("Index", "DetailPengiriman", new { compID = Request.QueryString["compID"] }, FormMethod.Post))
{
<b>Search By:</b>
#Html.RadioButton("searchBy", "CustID", true) <text>CustomerID</text>
#Html.RadioButton("searchBy", "Fullname") <text>Customer Name</text>
<br />
#Html.TextBox("search")
<input type="submit" value="Search" />
}
</p>
<table class="table">
<tr>
<th>
#Html.ActionLink("Transaction Date", "Index", new
{
sortBy = ViewBag.SortDateParam,
searchBy = Request.QueryString["searchBy"],
search = Request["search"],
compID = Request["compID"]
})
</th>
<th>
CustomerID
</th>
<th>
Customer Name
</th>
<th>
Invoice
</th>
<th>
Nama Penerima
</th>
<th>
Status Penerima
</th>
<th>
#Html.ActionLink("Status", "Index", new
{
sortBy = ViewBag.SortStatusParam,
searchBy = Request.QueryString["searchBy"],
search = Request["search"],
compID = Request["compID"]
})
</th>
<th>
Status Date
</th>
<th>
Image
</th>
<th>Actions</th>
</tr>
#foreach (var item in Model) {
<tr>
<td>
#Html.DisplayFor(modelItem => item.TrDate)
</td>
<td>
#Html.DisplayFor(modelItem => item.Customer.CustID)
</td>
<td>
#Html.DisplayFor(modelItem => item.Customer.Fullname)
</td>
<td>
#Html.DisplayFor(modelItem => item.InvoiceNo)
</td>
<td>
#Html.DisplayFor(modelItem => item.NamaPenerima)
</td>
<td>
#Html.DisplayFor(modelItem => item.StatusPenerima)
</td>
<td>
#Html.DisplayFor(modelItem => item.Status.Status1)
</td>
<td>
#Html.DisplayFor(modelItem => item.Status.StatDate)
</td>
<td>
#if (item.Image.Image1 != null)
{
var base64 = Convert.ToBase64String(item.Image.Image1);
var imgSrc = ($"data:image/png;base64,{base64}");
<img src="#imgSrc" width="50" height="50"
onMouseOut="zoomtoggle('50','50px','50px','50px',this);"
onMouseOver="zoomtoggle('400px','200px','400px','200px',this);"/>
}
else
{
<text> No Image Available</text>
}
</td>
<td>
#Html.ActionLink("Edit", "Edit", new
{
id = item.TransID,
custID = item.CustID,
statID = item.StatusID,
imgID = item.ImageID,
invoNo = item.InvoiceNo
}) |
#Html.ActionLink("Delete", "Delete", new
{
id = item.TransID,
custID = item.CustID,
statID = item.StatusID,
imgID = item.ImageID,
invoNo = item.InvoiceNo
})
</td>
</tr>
}
</table>
#Html.PagedListPager(Model, page => Url.Action("Index", new
{
page,
searchBy = Request.QueryString["searchBy"],
search = Request.QueryString["search"],
sortBy = Request["sortBy"],
compID = Request["compID"]
}),
new PagedListRenderOptions() { Display = PagedListDisplayMode.IfNeeded })
I want the view listed the data from database group by month in TrDate attribute
TrDate data are from datetime.now
TrDate data type is DateTime