MVC where logic must follow a controller or view model

Question

I have an MVC application where I want to display a drop-down list with information from a database.

The drop-down list will display information from the Cars database using the Make table, which is the brand of the car.

So, in my opinion, I will have something like:

@model VectorCheck.ViewModels.CarsViewModel ... @Html.DropDownListFor(modelItem => Model.MakeId, Model.Makes) ... 

So somehow I need to get the view model in the make list.

So, I can have some logic to go with this, say only cars that are painted red.

 var redCars = _unitOfWork.Cars(x => x.Colour == "Red"); 

So my question is where is the best place to put the logic for this request. Whether it should be in the Model view or controller.

As I can see, I have two options.

Option 1: controller.

 public ActionResult Edit(int id) { var car = _unitOfWork.CarRepository.Get(id); var carMakes = _unitOfWork.CarMakeRepository.Where(x => x.Colour == "Red").Select(u => new SelectListItem { Value = u.CarMakeId.ToString(), Text = u.Name }); return View("Edit", new InsertUpdateCarViewModel(car, carMakes)); } 

ViewModel

 public Car Car { get; set; } public IEnumerable<SelectListItem> CarMakes { get; set; } InsertUpdateCarViewModel(Car car, IEnumerable<SelectListItem> carMakes) { Car= car; CarMakes = carMakes; } 

So, in this example, I get carMakes in the controller and pass them to viewModel, which is just a container.

Opon 2: ViewModel

 public ActionResult Edit(int id) { var car = _unitOfWork.CarRepository.Get(id); return View("Edit", new InsertUpdateCarViewModel(car)); } 

ViewModel

 public Car Car { get; set; } public IEnumerable<SelectListItem> CarMakes { get; set; } InsertUpdateCarViewModel(Car car) { Car= car; CarMakes = _unitOfWork.CarMakeRepository.Where(x => x.Colour == "Red").Select(u => new SelectListItem { Value = u.CarMakeId.ToString(), Text = u.Name }); } 

So, in this option, I put the logic to get the correct models in the view model. It is more than a container.

So I want to know which of these methods is the right way to do this?

Answer 1

In the controller. ViewModel does not need to know what part of the work you are using. In addition, the presentation model in this case would be much more reusable if it did not have to rely on the logic x => x.Colour == "Red" . Despite the fact that this can be carried over to the arguments, in general, I believe that your models (and, consequently, their types) will be much more reused if you take care of this in the controller.

Answer 2

As already mentioned, this is the controller. To make it more memorable for you, I would say so. Do not let your view access the database directly. View asks / talks only to the controller. Then, obviously, it makes sense for the submission to send a request to the controller, which sends it to the database. Hope this helps in the future!

Answer 3

You must add your logic to the controller. In MVC, a ViewModel is an object that contains the properties used in your view, not the business logic.

Answer 4

Any answer would be very subjective, but I would suggest that having the _unitOfWork link (or any dependency that requires an injection) in your view model is a pretty cruel separation of concerns.

Keep it in the controller - much cleaner.