搜索整个网站而不是一组产品

Question

我有一个搜索 controller ，它获取 Searchid 和 keywordSearch 以显示搜索结果。 例如，用户可以在移动类别中搜索 iPhone。 我正在尝试对所有产品组（Searchid）中的任何关键字（KeywordSearch）进行搜索，我需要帮助。

HTML 代码：

<div class="top_search_form">

@using (Html.BeginForm("Search", "Home", FormMethod.Get, new { @class = "search_form clearfix", @id = "frm_topsearch" }))
{
    <div id="search_box">
        <select name='Searchid' style="margin-left:1px;">
            @foreach (var item1 in repsearch.GetGroup())
            {
                <option value='@item1.Group_ID'>@item1.Group_Name</option>
            }

        </select>


        <input type="text" placeholder="search" name='keywordSearch'>

        <input type="submit" class="fa fa-search" style="margin-right: 1px;width:38px !important;background-color: #CC456B !important;height: 34px !important;" name="name" value="search" />


    </div>

    <div id="search_result_box">

    </div><!-- end search_result_box -->
}

controller：

[HttpGet]
    public ActionResult Search(int Searchid, string keywordSearch)
    {
        var qid = db.Tbl_Group.Where(a => a.Group_ID == Searchid).FirstOrDefault();

        if (qid == null)
        {
            return RedirectToAction("Index");
        }
        else
        {
            if (keywordSearch == "" || keywordSearch == null)
            {
                var q = db.Tbl_Product.Where(a => a.Product_Groupid == Searchid).ToList();

                if (q == null)
                {
                    ViewBag.State = "Error";
                    ViewBag.Key = keywordSearch;
                    ViewBag.Groupid = Searchid;
                    return View();
                }
                else
                {

                    ViewBag.State = "Ok";
                    ViewBag.Key = keywordSearch;
                    ViewBag.Groupid = Searchid;
                    return View(q);
                }
            }
            else
            {
                var search = (from a in db.Tbl_Product where a.Product_Groupid == Searchid && a.Product_Name.Contains(keywordSearch) select a).ToList();

                if (search == null)
                {
                    ViewBag.State = "Error";
                    ViewBag.Key = keywordSearch;
                    ViewBag.Groupid = Searchid;
                    return View();

                }
                else
                {
                    ViewBag.State = "Error";
                    ViewBag.Key = keywordSearch;
                    ViewBag.Groupid = Searchid;
                    return View(search);
                }
            }
        }

    }