如何使用viewmodels插入记录：Asp.Net Mvc

Question

Introduction

I am working with the mvc project, implementation approach is code-first. Domain Model i am using, have more than 70 fields.So i made ViewModels.

Need for making view model is due to creating form wizard which store information in server side(Session Variable).

Domain Model

public class RegisterationDM
{
[DatabaseGenerated(DatabaseGeneratedOption.Identity)]
        [Key]
        public int RegisterationId { get; set; }
//other fields
}

Main View Model

public class RegistrationViewModel
{
        public PersonalViewModel PersonalViewModel {get;set; }
        public DetailViewmodel DetailedViewmodel { get; set; }
        public PhysicalDetailViewModel PhysicalDetailViewModel { get; set; }
        public RequirementViewModel RequirementViewModel { get; set; }
        public CreationInfoViewModel CreationInfoViewModel { get; set; }
}

Separate Classes

public class PersonalViewModel()
{
//fields
}
public class DetailViewmodel()
{
//fields
}
public class PhysicalDetailViewModel()
{
//fields
}
public class RequirementViewModel()
{
fields
}
public class CreationInfoViewModel()
{
//fields
}

Record Insertion Code

public ActionResult SaveInformation()
        {
            RegisterationDM regdm = new RegisterationDM();
            RegistrationViewModel regvm = new RegistrationViewModel();

            PersonalViewModel personalvm = (PersonalViewModel)Session["Personal"];
            DetailViewmodel detailvm = (DetailViewmodel)Session["Detail"];
            PhysicalDetailViewModel physicalvm = (PhysicalDetailViewModel)Session["Physical"];
            RequirementViewModel requirementvm = (RequirementViewModel)Session["Requirement"];

            CreationInfoViewModel createdinforvm = new CreationInfoViewModel();
            createdinforvm.CreatedBy = "";
            createdinforvm.CreatedDate = DateTime.Now;

            regvm.PersonalViewModel = personalvm;
            regvm.DetailedViewmodel = detailvm;
            regvm.PhysicalDetailViewModel = physicalvm;
            regvm.RequirementViewModel = requirementvm;
            regvm.CreationInfoViewModel = createdinforvm;
            //here assigning of view model to domain model
            db.Reg.Add(regdm);
            db.SaveChanges();
            return View();
        }

All Actions(Updated)

public ActionResult Step1()
        {
            RegistrationViewModel regvm = new RegistrationViewModel();
            return View(regvm.PersonalViewModel);
        }
        [HttpPost]
        public ActionResult Step1(PersonalViewModel personalvm)
        {
            if (ModelState.IsValid)
            {
                //Store the wizard in session
                Session["Personal"] = personalvm;
                return RedirectToAction("Step2");
            }
            else
            { 
            return View(personalvm);
            }
        }

        public ActionResult Step2()
        {
            if (Session["Personal"] != null)
            {
                RegistrationViewModel regvm = new RegistrationViewModel();
                return View(regvm.DetailedViewmodel);
            }
            else
            {
                return RedirectToAction("Step1");
            }
        }
        [HttpPost]
        public ActionResult Step2(DetailViewmodel detailvm)
        {
            if (ModelState.IsValid)
            {
                //Store the wizard in session
                Session["Detail"] = detailvm;
                return RedirectToAction("Step3");
            }
            return View(detailvm);
        }

        public ActionResult Step3()
        {
            if (Session["Detail"] != null && Session["Personal"] != null)
            {
                RegistrationViewModel regvm = new RegistrationViewModel();
                return View(regvm.PhysicalDetailViewModel);
            }
            else
            {
                return RedirectToAction("Step1");
            }
        }
        [HttpPost]
        public ActionResult Step3(PhysicalDetailViewModel physicalsvm)
        {
            if (ModelState.IsValid)
            {
                //Store the wizard in session
                Session["Physical"] = physicalsvm;
                return RedirectToAction("Step4");
            }
            return View(physicalsvm);
        }

        public ActionResult Step4()
        {
            if (Session["Detail"] != null && Session["Personal"] != null && Session["Physical"] != null)
            {
                RegistrationViewModel regvm = new RegistrationViewModel();
                return View(regvm.RequirementViewModel);
            }
            else
            {
                return RedirectToAction("Step1");
            }
        }
        [HttpPost]
        public ActionResult Step4(RequirementViewModel requirementvm)
        {
            if (ModelState.IsValid)
            {
                Session["Requirement"] = requirementvm;
                return RedirectToAction("SaveInformation");
            }
            return View(requirementvm);
        }

Question

How can i add(record) using main view model.Should i map first?

I understand its not possible like that.So i ask, is there a proper way of doing that.What it might be?The best way, the right way or the wrong way? I will prefer standard implementation even if it is hard to implement.

If someone have ideas about this problem, please do help.Any kind of help or reference will be appreciated.Thanks for your time.

(Due to lack of knowledge, may be i made some mistakes.Down Voters are welcome but please leave comment so i can improve question.)

Answer 1

By Defining your own Custom model binder would be suitable for such scenarios. I would recommend you to find some useful resources to get knowledge on how to implement this, Also this is one simple straight forward article CodeProject Custom Model Binder . Let me know if this was useful

Answer 2

We used Automapper to map fields. It is very helpful. Keeps code clean. It has customizable pre and post mapping functions too.