diff --git a/2020-Jan-Season/SoftUni-Information-Services/SIS/SIS.MvcFramework/WebHost.cs b/2020-Jan-Season/SoftUni-Information-Services/SIS/SIS.MvcFramework/WebHost.cs
index ac434325..ed8c0b5d 100644
--- a/2020-Jan-Season/SoftUni-Information-Services/SIS/SIS.MvcFramework/WebHost.cs
+++ b/2020-Jan-Season/SoftUni-Information-Services/SIS/SIS.MvcFramework/WebHost.cs
@@ -88,7 +88,16 @@ private static HttpResponse InvokeAction(HttpRequest request, IServiceCollection
                     foreach (var property in parameter.ParameterType.GetProperties(BindingFlags.Public | BindingFlags.Instance))
                     {
                         var propertyValue = GetValueFromRequest(request, property.Name);
-                        property.SetValue(parameterValue, Convert.ChangeType(propertyValue, property.PropertyType));
+
+                        if (property.PropertyType.IsGenericType &&
+                            property.PropertyType.GetGenericTypeDefinition() == typeof(Nullable<>))
+                        {
+                            property.SetValue(parameterValue, null);
+                        }
+                        else
+                        {
+                            property.SetValue(parameterValue, Convert.ChangeType(propertyValue, property.PropertyType));
+                        }
                     }
 
                     actionParameterValues.Add(parameterValue);
diff --git a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Controllers/HomeController.cs b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Controllers/HomeController.cs
index 19fbb403..870f342e 100644
--- a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Controllers/HomeController.cs
+++ b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Controllers/HomeController.cs
@@ -12,12 +12,12 @@ namespace SulsApp.Controllers
     public class HomeController : Controller
     {
         private readonly ILogger logger;
-        private readonly ApplicationDbContext db;
+        private readonly IProblemsService problemsService;
 
-        public HomeController(ILogger logger, ApplicationDbContext db)
+        public HomeController(ILogger logger, IProblemsService problemsService)
         {
             this.logger = logger;
-            this.db = db;
+            this.problemsService = problemsService;
         }
 
         [HttpGet("/")]
@@ -25,12 +25,7 @@ public HttpResponse Index()
         {
             if (this.IsUserLoggedIn())
             {
-                var problems = db.Problems.Select(x => new IndexProblemViewModel
-                {
-                    Id = x.Id,
-                    Name = x.Name,
-                    Count = x.Submissions.Count(),
-                }).ToList();
+                var problems = this.problemsService.GetProblems();
                 var loggedInViewModel = new LoggedInViewModel()
                 {
                     Problems = problems,
diff --git a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Controllers/ProblemsController.cs b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Controllers/ProblemsController.cs
index 28f51fb6..33ec8ef3 100644
--- a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Controllers/ProblemsController.cs
+++ b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Controllers/ProblemsController.cs
@@ -9,12 +9,10 @@ namespace SulsApp.Controllers
     public class ProblemsController : Controller
     {
         private readonly IProblemsService problemsService;
-        private readonly ApplicationDbContext db;
 
-        public ProblemsController(IProblemsService problemsService, ApplicationDbContext db)
+        public ProblemsController(IProblemsService problemsService)
         {
             this.problemsService = problemsService;
-            this.db = db;
         }
 
         public HttpResponse Create()
@@ -56,20 +54,7 @@ public HttpResponse Details(string id)
                 return this.Redirect("/Users/Login");
             }
 
-            var viewModel = this.db.Problems.Where(x => x.Id == id).Select(
-                x => new DetailsViewModel
-                {
-                    Name = x.Name,
-                    Problems = x.Submissions.Select(s =>
-                    new ProblemDetailsSubmissionViewModel
-                    {
-                        CreatedOn = s.CreatedOn,
-                        AchievedResult = s.AchievedResult,
-                        SubmissionId = s.Id,
-                        MaxPoints = x.Points,
-                        Username = s.User.Username,
-                    })
-                }).FirstOrDefault();
+            var viewModel = this.problemsService.GetDetailsProblems(id);
 
             return this.View(viewModel);
         }
diff --git a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Controllers/SubmissionsController.cs b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Controllers/SubmissionsController.cs
index 4497f13e..aa547156 100644
--- a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Controllers/SubmissionsController.cs
+++ b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Controllers/SubmissionsController.cs
@@ -12,12 +12,10 @@ namespace SulsApp.Controllers
 {
     public class SubmissionsController : Controller
     {
-        private readonly ApplicationDbContext db;
         private readonly ISubmissionsService submissionsService;
 
-        public SubmissionsController(ApplicationDbContext db, ISubmissionsService submissionsService)
+        public SubmissionsController(ISubmissionsService submissionsService)
         {
-            this.db = db;
             this.submissionsService = submissionsService;
         }
 
@@ -28,13 +26,7 @@ public HttpResponse Create(string id)
                 return this.Redirect("/Users/Login");
             }
 
-            var problem = this.db.Problems
-                .Where(x => x.Id == id)
-                .Select(x => new CreateFormViewModel
-                {
-                    Name = x.Name,
-                    ProblemId = x.Id,
-                }).FirstOrDefault();
+            var problem = this.submissionsService.GetProblem(id);
             if (problem == null)
             {
                 return this.Error("Problem not found!");
diff --git a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/IProblemsService.cs b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/IProblemsService.cs
index da3ecb8b..7d1e380f 100644
--- a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/IProblemsService.cs
+++ b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/IProblemsService.cs
@@ -1,4 +1,6 @@
-using System;
+using SulsApp.ViewModels.Home;
+using SulsApp.ViewModels.Problems;
+using System;
 using System.Collections.Generic;
 using System.Text;
 
@@ -7,5 +9,9 @@ namespace SulsApp.Services
     public interface IProblemsService
     {
         void CreateProblem(string name, int points);
+
+        IEnumerable<IndexProblemViewModel> GetProblems();
+
+        DetailsViewModel GetDetailsProblems(string id);
     }
 }
diff --git a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/ISubmissionsService.cs b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/ISubmissionsService.cs
index a4c39711..3522bd29 100644
--- a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/ISubmissionsService.cs
+++ b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/ISubmissionsService.cs
@@ -1,4 +1,5 @@
-using System;
+using SulsApp.ViewModels.Submissions;
+using System;
 using System.Collections.Generic;
 using System.Text;
 
@@ -9,5 +10,7 @@ public interface ISubmissionsService
         void Create(string userId, string problemId, string code);
 
         void Delete(string id);
+
+        CreateFormViewModel GetProblem(string id);
     }
 }
diff --git a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/ProblemsService.cs b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/ProblemsService.cs
index 55048e5a..8a4c3e3d 100644
--- a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/ProblemsService.cs
+++ b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/ProblemsService.cs
@@ -1,6 +1,9 @@
 using SulsApp.Models;
+using SulsApp.ViewModels.Home;
+using SulsApp.ViewModels.Problems;
 using System;
 using System.Collections.Generic;
+using System.Linq;
 using System.Text;
 
 namespace SulsApp.Services
@@ -24,5 +27,39 @@ public void CreateProblem(string name, int points)
             this.db.Problems.Add(problem);
             this.db.SaveChanges();
         }
+
+        public DetailsViewModel GetDetailsProblems(string id)
+        {
+            var viewModel = this.db.Problems
+               .Where(x => x.Id == id)
+               .Select(x => new DetailsViewModel
+               {
+                   Name = x.Name,
+                   Problems = x.Submissions.Select(s => new ProblemDetailsSubmissionViewModel
+                   {
+                       Username = s.User.Username,
+                       AchievedResult = s.AchievedResult,
+                       MaxPoints = x.Points,
+                       CreatedOn = s.CreatedOn,
+                       SubmissionId = s.Id
+                   })
+                   .ToList()
+               })
+               .FirstOrDefault();
+
+            return viewModel;
+        }
+
+        public IEnumerable<IndexProblemViewModel> GetProblems()
+        {
+            var problems = this.db.Problems.Select(x => new IndexProblemViewModel
+            {
+                Id = x.Id,
+                Name = x.Name,
+                Count = x.Submissions.Count
+            }).ToList();
+
+            return problems;
+        }
     }
 }
diff --git a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/SubmissionsService.cs b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/SubmissionsService.cs
index 160e350e..642ed2dc 100644
--- a/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/SubmissionsService.cs
+++ b/2020-Jan-Season/SoftUni-Information-Services/SIS/SulsApp/Services/SubmissionsService.cs
@@ -1,4 +1,5 @@
 using SulsApp.Models;
+using SulsApp.ViewModels.Submissions;
 using System;
 using System.Linq;
 
@@ -37,5 +38,18 @@ public void Delete(string id)
             this.db.Remove(submission);
             this.db.SaveChanges();
         }
+
+        public CreateFormViewModel GetProblem(string id)
+        {
+            var problem = this.db.Problems
+                .Where(x => x.Id == id)
+                .Select(x => new CreateFormViewModel
+                {
+                    Name = x.Name,
+                    ProblemId = x.Id
+                }).FirstOrDefault();
+
+            return problem;
+        }
     }
 }