Code First Using Entity Framework Core and ViewModel

Question

I am new to MVC and Entity Framework and have decided to use the Code First approach using ViewModels.

I have tried many different tutorials but no one that i've tried has used Code First in EF Core with ViewModels.

My Models

public class Intermediary
{
 public int IntermediaryID { get; set; }
 public string RegisteredName { get; set; }
 public string TradingName { get; set; }
 public int Registration { get; set; }
 public int VATNumber { get; set; }
 public int FSPNumber { get; set; }
 public DateTime CreatedDate { get; set; }
 public string CreatedBy { get; set; }
 public ICollection<Branch> Branches { get; set; }
}
public class Branch
{
 public int BranchID { get; set; }
 public string Name { get; set; }
 public DateTime CreatedDate { get; set; }
 public string CreatedBy { get; set; }
 public Intermediary Intermediary { get; set; }
}

My ViewModel

public class IntermediariesViewModel
{
 public int ID { get; set; }
 public Intermediary Intermediary { get; set; }
 public virtual ICollection<Branch> Branches { get; set; }
}

My Data Context Class

public class BizDevHubContext : DbContext
{
 public BizDevHubContext(DbContextOptions<BizDevHubContext> options) : base(options)
 {
 }
 public DbSet<Intermediary> Intermediaries { get; set; }
 public DbSet<Branch> Branches { get; set; }
 protected override void OnModelCreating(ModelBuilder modelBuilder)
 {
 modelBuilder.Entity<Intermediary>().ToTable("Intermediary");
 modelBuilder.Entity<Branch>().ToTable("Branch");
 }
}

My Initializer Class

public static class DbInitializer
{
 public static void Initialize(BizDevHubContext context)
 {
 context.Database.EnsureCreated();
 if (context.Intermediaries.Any())
 {
 return; // DB has been seeded
 }
 var intermediaries = new Intermediary[]
 {
 new Intermediary{RegisteredName="Carson",TradingName="Alexander",CreatedDate=DateTime.Now,CreatedBy="System"},
 new Intermediary{RegisteredName="Meredith",TradingName="Alonso",CreatedDate=DateTime.Now,CreatedBy="System"},
 new Intermediary{RegisteredName="Arturo",TradingName="Anand",CreatedDate=DateTime.Now,CreatedBy="System"},
 new Intermediary{RegisteredName="Gytis",TradingName="Barzdukas",CreatedDate=DateTime.Now,CreatedBy="System"},
 new Intermediary{RegisteredName="Yan",TradingName="Li",CreatedDate=DateTime.Now,CreatedBy="System"},
 new Intermediary{RegisteredName="Peggy",TradingName="Justice",CreatedDate=DateTime.Now,CreatedBy="System"},
 new Intermediary{RegisteredName="Laura",TradingName="Norman",CreatedDate=DateTime.Now,CreatedBy="System"},
 new Intermediary{RegisteredName="Nino",TradingName="Olivetto",CreatedDate=DateTime.Now}
 };
 foreach (Intermediary i in intermediaries)
 {
 context.Intermediaries.Add(i);
 }
 context.SaveChanges();
 var branches = new Branch[]
 {
 new Branch{Name="Bloemfontein",CreatedDate=DateTime.Now,CreatedBy="System"},
 new Branch{Name="Cape Town",CreatedDate=DateTime.Now,CreatedBy="System"},
 new Branch{Name="Durban",CreatedDate=DateTime.Now,CreatedBy="System"},
 new Branch{Name="Nelspruit",CreatedDate=DateTime.Now,CreatedBy="System"},
 new Branch{Name="Johannesburg",CreatedDate=DateTime.Now,CreatedBy="System"},
 new Branch{Name="Port Shepstone",CreatedDate=DateTime.Now,CreatedBy="System"},
 new Branch{Name="Pretoria",CreatedDate=DateTime.Now,CreatedBy="System"}
 };
 foreach (Branch b in branches)
 {
 context.Branches.Add(b);
 }
 context.SaveChanges();
 }
}

This all seems to work fine and the database gets created ok, but I am stuck now trying to create the Controller and Views

I managed to do it with a single model but cannot seem to get it right putting the entire viewmodel.

My Controller

using BizDevHub.ViewModels;
public async Task<IActionResult> Index()
{
 return View(await _context.Intermediaries.ToListAsync());
}
[HttpPost]
[ValidateAntiForgeryToken]
public async Task<IActionResult> Create([Bind("ID")] Intermediaries Intermediaries)
{
 if (ModelState.IsValid)
 {
 _context.Add(Intermediaries);
 await _context.SaveChangesAsync();
 return RedirectToAction(nameof(Index));
 }
 return View(Intermediaries);
}

The same goes for my views

My View

@model IEnumerable<BizDevHub.Models.Intermediary>
@{
 ViewData["Title"] = "Index";
 Layout = "~/Views/Shared/_Layout.cshtml";
}
<h2>Index</h2>
<p>
 <a asp-action="Create">Create New</a>
</p>
<table class="table">
 <thead>
 <tr>
 <th>
 @Html.DisplayNameFor(model => model.RegisteredName)
 </th>
 <th>
 @Html.DisplayNameFor(model => model.TradingName)
 </th>
 <th>
 @Html.DisplayNameFor(model => model.Registration)
 </th>
 <th>
 @Html.DisplayNameFor(model => model.VATNumber)
 </th>
 <th>
 @Html.DisplayNameFor(model => model.FSPNumber)
 </th>
 <th>
 @Html.DisplayNameFor(model => model.CreatedDate)
 </th>
 <th>
 @Html.DisplayNameFor(model => model.CreatedBy)
 </th>
 <th></th>
 </tr>
 </thead>
 <tbody>
@foreach (var item in Model) {
 <tr>
 <td>
 @Html.DisplayFor(modelItem => item.RegisteredName)
 </td>
 <td>
 @Html.DisplayFor(modelItem => item.TradingName)
 </td>
 <td>
 @Html.DisplayFor(modelItem => item.Registration)
 </td>
 <td>
 @Html.DisplayFor(modelItem => item.VATNumber)
 </td>
 <td>
 @Html.DisplayFor(modelItem => item.FSPNumber)
 </td>
 <td>
 @Html.DisplayFor(modelItem => item.CreatedDate)
 </td>
 <td>
 @Html.DisplayFor(modelItem => item.CreatedBy)
 </td>
 <td>
 <a asp-action="Edit" asp-route-id="@item.IntermediaryID">Edit</a> |
 <a asp-action="Details" asp-route-id="@item.IntermediaryID">Details</a> |
 <a asp-action="Delete" asp-route-id="@item.IntermediaryID">Delete</a>
 </td>
 </tr>
}
 </tbody>
</table>

What am I doing wrong?

Thanks in advance.

Answer 1

@Anonymous is correct that you need to redesign the View model. There is no point having a view model if you are just assigning entities as the properties, the purpose of the view model is to separate you controller and view from your datacontext

public class IntermediariesViewModel
{
 public int Id { get; set; }
 public string RegisteredName { get; set; }
 public string TradingName { get; set; }
 //other properties
 IEnumerable<BranchViewModel> Branches { get; set; }
}
public class BranchViewModel
{
 public int Id { get; set; }
 public string Name { get; set; }
}

View:

@model IEnumerable<BizDevHub.Models.IntermediariesViewModel>

EDIT : but how would you combine both view models in a single controller and view with methods like Index, Edit and Delete?

Controller:

public IActionResult Update([FromBody]IntermediariesViewModel model)
 {
 var intermediary = _context.Intermediaries.Where(x=> x.IntermediaryID == model.Id).FirstOrDefault();
 if(intermediary != null)
 {
 intermediary.RegisteredName = model.RegisteredName ;
 //rest of updates
 _context.SaveChanges();
 }
 }
 public IActionResult Delete([FromBody]int IntermediariesId)
 {
 var intermediary = _context.Intermediaries.Where(x=> x.IntermediaryID == IntermediariesId).FirstOrDefault();
 if(intermediary != null)
 {
 _context.Intermediaries.Remove(intermediary); 
 _context.SaveChanges();
 }
 }

View:

@Html.DisplayNameFor(model => model.RegisteredName)
@Html.DisplayNameFor(model => model.BranchViewModel[0].Name)// first branch name, you may want to iterate

• Jason Ebersey: Thank you Vince, but how would you combine both view models in a single controller and view with methods like Index, Edit and Delete?
• Vince: @JasonEbersey see update, also hello fellow South African