Добавил обработку пустых запросов

PaydayFrontend/Controllers/HomeController.cs

@@ -29,11 +29,13 @@ public class HomeController : Controller
         var random = new Random(DateTime.Now.Millisecond);
         universities = universities.OrderBy(x => random.Next()).ToList();
 
-        return View(universities.ToList());
+        var answer = new UniversityViewModel(universities, searchString);
+
+        return View(answer);
     }
     
     [Route("Directions")]
-    public async Task<IActionResult> Directions(long universityId)
+    public async Task<IActionResult> Directions(long universityId, string searchString)
     {
         if (universityId == 0)
             return RedirectToAction("Index");
@@ -41,9 +43,17 @@ public class HomeController : Controller
         var answer = new UniversityDirectionsViewModel();
         answer.University = await _universityService.GetUniversityById(universityId);
         answer.Directions = await _universityService.GetDirectionsByUniversityId(universityId);
+        answer.SearchString = searchString;
+        
+        if (!String.IsNullOrEmpty(searchString))
+        {
+            answer.Directions = answer.Directions.Where(s => s.Name!.ToLower().Contains(searchString.ToLower()) || s.Code!.ToLower().Contains(searchString.ToLower())).ToList();
+        }
+
         return View(answer);
     }
     
+    [Route("Credits")]
     public IActionResult Credits()
     {
         return View();