MVC 5 dropdown value when selected - asp.net-mvc

Question

I have a category and sub category dropdown list in my view. I select the items in the DDL and submit. In my controller I can only see the categoryID, subCategoryID values for the DDL. I need to get the selected text values (categoryName, subCategoryName). In winforms it is known as the DisplayMember.
I can get the categoryName, subcategoryName values if I run a query based on the returned ID, but this feels like I'm hitting the database more times than I need to.
Here is my code:
ViewModel
public class MedicalCategoryVM
{
public int PersonID { get; set; }
public int CategoryID { get; set; }
public string CategoryName { get; set; }
public int SubCategoryID { get; set; }
public string SubCategoryName { get; set; }
public string Notes { get; set; }
public Nullable<System.Guid> RowGuid { get; set; }
public Nullable<System.DateTime> ModifiedDate { get; set; }
public virtual Person Person { get; set; }
public List<MedicalCategory> MedicalCategories { get; set; }
}
View:
#model DofE.Models.MedicalCategoryVM
<br />
<br />
#using (Html.BeginForm())
{
#Html.AntiForgeryToken()
<div class="container">
#Html.Label("Medical Information", new { style = "font-size:16px; background-color:#002142; color:white;margin-left:10px" })
<div class="form-group">
#Html.DropDownListFor(model => model.CategoryID, new SelectList(Model.MedicalCategories,"CategoryID","CategoryName"),"--Select", new { #class = "form-control" })
</div>
<div class="form-group">
#Html.DropDownListFor(model => model.SubCategoryID, new SelectList(""), "--Select Sub Category", new { #class = "form-control" })
</div>
<div class="form-group">
<div class="row">
#Html.LabelFor(model => model.Notes, htmlAttributes: new { #class = "control-label col-md-2" })
<div class="col-md-10">
#Html.EditorFor(model => model.Notes, new { htmlAttributes = new { #class = "form-control" } })
#Html.ValidationMessageFor(model => model.Notes, "", new { #class = "text-danger" })
</div>
</div>
</div>
<div class="form-group">
<div class="row">
#Html.LabelFor(model => model.PersonID, htmlAttributes: new { #class = "control-label col-md-2" })
<div class="col-md-10">
#Html.EditorFor(model => model.PersonID, new { htmlAttributes = new { #class = "form-control" } })
#Html.ValidationMessageFor(model => model.PersonID, "", new { #class = "text-danger" })
</div>
</div>
</div>
<div class="form-group">
<div style="padding-left:340px">
<span style="display: inline;">
#Html.ActionLink("Cancel", "Index", null, new { #class = "btn btn-danger btn-sm" }) <input type="submit" value="Create" class="btn btn-primary btn-sm" />
</span>
</div>
#*<div class="test">
<div style="float: right;">
<input type="submit" value="Create" class="btn btn-primary" />
</div>
</div>*#
</div>
</div>
}
<script src="~/Scripts/jquery-3.4.1.min.js"></script>
<script>
$(document).ready(function () {
$("#CategoryID").change(function () {
$.get("/MedicalHistory/GetSubCategoryList", { CategoryID: $("#CategoryID").val() }, function (data) {
$("#SubCategoryID").empty();
$.each(data, function (index, row) {
$("#SubCategoryID").append("<option value='" + row.SubCategoryID + "'>" + row.SubCategoryName + "</option>")
});
});
})
});
</script>
Controller:
public ActionResult Create()
{
MedicalCategoryVM CategoryVM = new MedicalCategoryVM();
CategoryVM.MedicalCategories = db.MedicalCategories.ToList();
//ViewBag.CategoryList = new SelectList(CategoryList, "CategoryID", "CategoryName");
return View(CategoryVM);
}
[HttpPost]
[ValidateAntiForgeryToken]
public ActionResult Create([Bind(Include = "PersonID,CategoryName,SubCategoryName,Notes,RowGuid,ModifiedDate")] MedicalHistory medicalHistory, FormCollection form)
{
//string catName = form["CategoryName"].ToString();
//string subCatName = form["SubCategoryName"].ToString();
int catID = Convert.ToInt16(form["CategoryID"]);
int subCatID = Convert.ToInt16(form["SubCategoryID"]);
MedicalSubCategory cat = db.MedicalSubCategories.Find(subCatID);
medicalHistory.CategoryName = cat.CategoryName;
medicalHistory.SubCategoryName=cat.SubCategoryName;
medicalHistory.RowGuid = Guid.NewGuid();
medicalHistory.ModifiedDate = DateTime.Now;
if (ModelState.IsValid)
{
db.MedicalHistories.Add(medicalHistory);
db.SaveChanges();
return RedirectToAction("Index");
}
return View(medicalHistory);
}