Web API oData - Should I forget about view models?

Question

Ive been working with MVC for a while now and am used to creating a View Model class for every MVC view. Now I am trying out Web API and I think I may be hung up on this MVC mentality. My relationship looks like this:

public class Supplier
{
    public int Id { get; set; }
    public string Title { get; set; }

    public virtual ICollection<SupplierProduct> SupplierProducts { get; set; }
}

public class Product
{
    public int Id { get; set; }
    public string Title { get; set; }

    public virtual ICollection<SupplierProduct> SupplierProducts { get; set; }
}

public class SupplierProduct
{
    public int Id { get; set; }
    public string Title { get; set; }

    public int SupplierId { get; set; }
    public virtual Supplier Supplier { get; set; }

    public int ProductId { get; set; }
    public virtual Product Product { get; set; }
}

I am working on the creation of the supplier where in the create form the user is able to select multiple products that already exist. In MVC, I would POST a view model that looks something like this:

public class SupplierCreateViewModel
{
    public string Title { get; set; }
    public ICollection<ProductViewModel> SelectedProducts { get; set; }
}

And in the controller I would first create the new Supplier then create a new SupplierProduct for each SelectedProduct. I implemented something like this in Web API in the POST action of my Supplier oData controller but it doesnt feel right. I think that instead, I need to change my approach and do something like this from the client:

1. Scrap the View Model design. (There arent really 'views' anymore anyway)
2. Have both a Supplier and a SupplierProduct Controller with a POST action on both.
3. On save, send my Supplier create request to POST api/Suppliers/.
4. Using the Id of the Supplier JSON in the response, send multiple create requests to POST api/SupplierProduct.

So my questions are:

1. Am I heading in the right direction with this approach?
2. Instead of View Models is there a different pattern I should use? DTO?
3. With the example given, am I forced to send 1 - n requests like that? This feels wrong.

Answer 1

Actually, it depends on your use-case. If your API is totally faced publicly, i would advice using DTO's. If it is for yourselve or for an internal team, i would stick with OData EF Models ( because it is quicker)

• You can ( as usual) give the entire entity through your api.

• You can use a viewmodel ( more like DTO's when using it in an API, but it's the same thing) and transform the methods accordingly. You can use automapper for that - it also transforms the $filter query, an example is found here : Web API Queryable - how to apply AutoMapper?.

Don't forget, an API has a lot of awesome advantages. OData uses Batch and Patch to change your entities. So i personally stick with Odata as entites most of the time, but that's a personal choice.