How to check if any model item is assigned a value in MVC? - asp.net-mvc

Question

I have a model which have properties.And, i want to check that if any model item has some value or not.Also,no property is set to mandatory or optional using data-annotations.If no property is assigned and any value then i should set some model error e.g "Please specify some search criteria."
#using (Html.BeginForm("GetAdvanceSearchData", "Home", FormMethod.Post)){
<div class="rTableCell" style="border:none !important">
#Html.TextBoxFor(m => m.MessageStatus, new { placeholder = Html.DisplayNameFor(n => n.MessageStatus), #class = "fieldtextbox", #style = "height: 25px !important" })
#Html.ValidationMessageFor(m => m.MessageStatus)
</div>
<div class="rTableCell" style="border:none !important">
#Html.TextBoxFor(m => m.RequestType, new { placeholder = Html.DisplayNameFor(n => n.RequestType), #class = "fieldtextbox", #style = "height: 25px !important" })
#Html.ValidationMessageFor(m => m.RequestType)
</div>
<div class="rTableCell" style="border:none !important">
</div>
<div class="rTableCell" style="border:none !important">
<p class="submit">
<button type="submit" name="submit">
<i class="fa fa-arrow-right" aria-hidden="true"></i>
</button>
</p>
</div>
}
These are only few properties for the model.

Answer 1

In action method GetAdvanceSearchData you can do your own validity checks, in addition to validation attributes, or instead of them.
If you add an entry to ModelState then ModelState.IsValid will become false, and the added entry will show in the output of Html.ValidationMessageFor(...) or Html.ValidationSummary().
Example:
[HttpPost]
public ActionResult GetAdvanceSearchData(YourModel vm)
{
if (vm == null || (string.IsNullOrEmpty(vm.MessageStatus) && string.IsNullOrEmpty(vm.RequestType)))
{
ModelState.AddModelError("", "Please specify some search criteria")
// Using "" as Key will only show when you use #Html.ValidationSummary().
// Using "myErr" as Key will show when you use #Html.ValidationMessage("myErr").
// Using a property name as Key will show it next to the property if you use #Html.ValidationMessageFor(m => m.property).
}
if (ModelState.IsValid)
{
var results = ...
return View("ResultsView", results);
}
else
{
return View(vm);
}
}