MVC Design Pattern – Combining Multiple Models for Use

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In my design, I have multiple models and each model has a controller. I need to use all the models to process some operation. Most examples I see are pretty simple with 1 view, 1 controller, and 1 model. How would you get all these models together?

Only ways I can think of are

1) Have a top-level controller which has a reference to every controller. Those controllers will have a getter/setter function for their model.

Does this violate MVC because every controller should have a model?

2) Have an Intermediate class to combine every model into a one model. Then you create a controller for that new super model.

Do you know of any better ideas? Thanks.

Best Answer

MVC is better viewed as a logical rather than physical construct.

You are free to create a model out of other models or take the repository (if you have one) in its entirety as the model if you need to. Some frameworks for example promote the use of viewmodels for such purposes when you wish to create a single model that is consumed by the view.

Likewise in the view, you can create multiple views based on the viewmodel. Whilst the code for this may sit in one physical view, logically they are different.

If you find yourself passing round the same model for everything, this might indicate that you have a god object which is obviously best avoided.

Related Solutions

Mvc – In ASP.NET MVC, should the view models have an ID

The ViewModel object is not what gets stored in a database table, generally. It's the individual items in the ViewModel object that get stored. Each of those items already has an ID.

For example:

public class InvoiceViewModel
{
    public Customer Customer { get; set; }
    public Address BillingAddress { get; set; }
    public Address ShippingAddress { get; set; }
    public List<InvoiceLineItem> Items { get; set; }
}

Since there's no single table in the database that corresponds to an InvoiceViewModel, there is no ID for an InvoiceViewModel object.

Of course, you can always use the InvoiceID as the id for this particular ViewModel. InvoiceID is handy, because that's what this object ultimately represents. But I could see having a ViewModel object that doesn't correspond to any particular ID in the database.

MVC Design – One vs Multiple Models for Multiple Views and Controllers

How about secret option 4?

Extract the common code into helpers / base classes, and extend or include as necessary?

This removes the duplication, and avoids putting anything more than what is actually used in each model.

You end up with one model per controller, and some helpers and base classes that (provided you organized and named them carefully) will be obvious in their function.

Best Answer

Related Solutions

Mvc – In ASP.NET MVC, should the view models have an ID

MVC Design – One vs Multiple Models for Multiple Views and Controllers

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