ASP.NET MVC Patterns

Question

I am fairly new to MVC, but after playing with it (MVC 3/Razor), I am hooked.

I have a few questions:

1) What is the best, or most widely used pattern to dev

Answer 1

I use generic repositories that get instantiated in a service class (using Dependency Injection with Ninject).

The service class essentially performs two functions:

1. It provides all the methods that the controller will consume.

2. It has a property called ViewModel, that essentially maps the data that the views need into a MyViewModel class.

The Controller consumes the service class. With this "pattern", your controllers look like:

namespace ES.eLearningFE.Areas.Courses.Controllers
{
    public partial class CourseController : Controller
    {
        ICourseDisplayService service;
        public CourseController(ICourseDisplayService service)
        {
            this.service = service;
        }

        public virtual ActionResult Display(int CourseId, int StepOrder, string PupilName, string TutorName)
        {
            service.CourseId = CourseId;
            service.StepOrder = StepOrder;
            service.PupilName = PupilName;
            service.TutorName = TutorName;
            if (Request.IsAjaxRequest())
            {
                return PartialView(service.ViewModel);
            }
            else
            {
                return View(service.ViewModel);
            }
        }

    }
}

The ViewModel class only hold display data and no methods (except the odd really simple method to retrieve data from another property that is, for example a List<> object).

Works really well. An example of a service class:

namespace ES.eLearning.Domain.Services.Courses
{
    public class SqlCourseDisplayService : ICourseDisplayService
    {
        DataContext db;

        public SqlCourseDisplayService(DbDataContextFactory contextFactory)
        {
            db = contextFactory.Make();
            CoursesRepository      = new SqlRepository(db);
            StepsRepository        = new SqlRepository(db);
            StepLinksRepository    = new SqlRepository(db);
            UserCoursesRepository  = new SqlRepository(db);
            CourseTutorsRepository = new SqlRepository(db);
            UsersRepository        = new SqlRepository(db);
        }
        #region ICourseDisplayService Members

        public ViewModels.CourseDisplayVM ViewModel
        {
            get
            {
                return new ViewModels.CourseDisplayVM
                {
                    CourseId = this.CourseId,
                    CourseName = this.Course.Name,
                    Steps = this.Steps,
                    ActiveStepIndex = this.ActiveStepIndex,
                    CurrentStepIndex = this.CurrentStepIndex,
                    Pupil = new UserDto { UserId = this.PupilId, UserName = this.PupilName },
                    Tutors = this.GetTutors(this.CourseId),
                    Tutor = tutorName == null ? null : new UserDto { UserName = this.TutorName, UserId = this.TutorId}
                };
            }
        }

        #region Entities

        int courseId;
        public int CourseId
        {
            get
            {
                if (courseId == 0) throw new ApplicationException("Invalid Course Id!");
                return courseId;
            }
            set
            {
                if (value == 0) throw new ApplicationException("Invalid Course Id!");
                try
                {
                    Course   = (from c in CoursesRepository.Query where c.CourseId == value select c).First();
                    Steps    = Course.CourseSteps.ToList();
                    courseId = value;
                }
                catch {throw new ApplicationException("No Course found for Course Id: " + value);}
            }
        }

        public Data.Course Course { get; private set; }

        public int StepOrder { get; set; }

        public List Steps { get; private set; }

        public int ActiveStepIndex
        {
            get
            {
                if (PupilName == null)
                {
                    throw new ApplicationException("Pupil not set!");
                }
                if (CourseId == 0)
                {
                    throw new ApplicationException("Course not set!");
                }
                try
                {
                    var x = (from uc in UserCoursesRepository.Query where (uc.IdCourse == CourseId) && (uc.UserName == PupilName) select uc).First();
                    return x.ActiveStepIndex;
                }
                catch { throw new ApplicationException("Could not get Active Step!"); }
            }
        }

        #endregion

        #region Users

        string tutorName;
        public string TutorName
        {
            get 
            {
                if (tutorName == null) throw new ApplicationException("Invalid call to get Tutor Name [Null Tutor Name]!");
                return tutorName; 
            }
            set
            {
                tutorName = value;
                TutorId = (Guid)Membership.GetUser(tutorName).ProviderUserKey;
            }
        }

        public Guid TutorId { get; set; }

        string pupilName;
        public string PupilName
        {
            get { return pupilName; }
            set
            {
                pupilName = value;
                PupilId = (Guid)Membership.GetUser(pupilName).ProviderUserKey;
            }
        }

        public Guid PupilId { get; set; }

        #endregion

        #region Utility Properties

        public int CurrentStepIndex { get; set; }
        public int StepCount
        {
            get
            {
                return Steps == null ? 0 : Steps.Count();
            }
        }

        #endregion

        #region Private Utilities

        private List GetTutors(int CourseId)
        {
            return (from ct in CourseTutorsRepository.Query join u in UsersRepository.Query
                    on ct.TutorName equals u.UserName
                    where (ct.CourseId == courseId) 
                    select new UserDto { UserName = ct.TutorName, UserId = u.UserId }).ToList();
        }

        #endregion

        #region Repositories

        private IRepository CoursesRepository
        {
            get;
            set;
        }

        private IRepository StepsRepository
        {
            get;
            set;
        }

        private IRepository StepLinksRepository
        {
            get;
            set;
        }

        private IRepository UserCoursesRepository
        {
            get;
            set;
        }

        private IRepository CourseTutorsRepository
        {
            get;
            set;
        }

        private IRepository UsersRepository
        {
            get;
            set;
        }

        #endregion

        #endregion
    }
}

May not be everyone's choice, but hey, it works for me... AND (more importantly) my clients and their users.

Edit

As requested in the comment below, the Repository that I use:

namespace ES.eLearning.Domain
{
    public class SqlRepository : IRepository where T : class
    {
        DataContext db;
        public SqlRepository(DataContext db)
        {
            this.db = db;
        }

        #region IRepository Members

        public IQueryable Query
        {
            get { return db.GetTable(); }
        }

        public List FetchAll()
        {
            return Query.ToList();
        }

        public void Add(T entity)
        {
            db.GetTable().InsertOnSubmit(entity);
        }

        public void Delete(T entity)
        {
            db.GetTable().DeleteOnSubmit(entity);
        }

        public void Attach(T entity)
        {
            db.GetTable().Attach(entity);
        }

        public void Save()
        {
            db.SubmitChanges();
        }

        #endregion
    }
}

And the IRepository Interface:

namespace Wingspan.Web.Mvc
{
    public interface IRepository where TEntity : class
    {
        List FetchAll();
        IQueryable Query {get;}
        void Add(TEntity entity);
        void Delete(TEntity entity);
        void Attach(TEntity entity);
        void Save();
    }
}