building view using a generic interface

Question

I am working on an ASP.Net MVC Website.

I have a table called animal, which is created based of this class using Entity Framework code first:

public class Animal
{
    public int AnimalId { get; set; }
    public string AnimalName { get; set; }
    public int NoOfLegs  { get; set; }

    public int FlyingSpeed { get; set; }
    public int RunningSpeed { get; set; }
}

Now I have my AnimalRepository that reads this info from the DB and pass it to my ViewModel (My Domain Classes are different from my ViewModel and I am using ModelReader, ModelWriter and AutoMapper to Map my domain model into my view model as explained here). I have this generic interface in my ViewModel:

public interface IAnimalModel
{
   int AnimalId { get; set; }
   string AnimalName { get; set; }
   int NoOfLegs  { get; set; }
}

And I have these two classes in my ViewModel:

public class DogModel: IAnimalModel
{
    public int AnimalId { get; set; }
    public string AnimalName { get; set; }
    public NoOfLegs  { get; set; }

    public int RunningSpeed { get; set; }
}

public class EagleModel: IAnimalModel
{
    public int AnimalId { get; set; }
    public string AnimalName { get; set; }
    public NoOfLegs  { get; set; }

    public int FlyingSpeed { get; set; }
}

Now I have one Animal Controller that uses AnimalRepositoy to get the data from DB, and maps it to the correct ViewModel.

I want to bind my View to IAnimalModel interface so that I can pass different animals to the same View.

In my View, I want to use Razor Code to display certain properties based on Animal Model type, something like this:

@if (typeof(Model) == typeof(EagleModel)) {
   Html.EditorFor(model => model.FlyingSpeed)
}

@if (typeof(Model) == typeof(DogModel)) {
   Html.EditorFor(model => model.RunningSpeed)
}

I have been thinking about this for a long time and I am not sure if this is a good solution? I have quite a few different Animal types with a lot of common properties, so don't really like the idea of creating one Table for each different animal.

I thought it's better to map them to correct type in my ViewModel...

I am not really sure if binding my ViewModel to IAnimalModel interface is a good idea? As I need to check the model type before displaying certain properties.

Another disadvantage is that in my DB, I don't know which type of animal each row contains... I am thinking maybe of I have to add a ViewModelType column to my Animal table, but again I am not sure if this is a good solution?

Answer 1

I think the problem is much simpler to be honest.

You're talking about a lot of animals but you could think in terms of types and then everything simplifies. So based on some very quick research, you have 6 animal types:

1. Invertebrates
2. Fish
3. Amphibians
4. Reptiles
5. Birds
6. Mammals

You can probably get away with less. So if you look at your problem from this point of view, now you don't have that many different types to look at.

So, have an animal type enum and use that to differentiate the fields you are displaying. In terms of database, I would not go with one table and null fields as that complicates everything. Either create a base one with whatever is common and a separate one for each type, or go with a Nosql db and save one type data per row.

Finally I don't really think that using a base interface gives you anything. You still have to repeat the fields in every class that implements it and you're not achieving anything in terms of simplification. If you instead go with a base abstract class then at least you don't have to repeat the same properties everywhere and your classes are now smaller and reflect the differences properly.