Should sorting logic be placed in the model, the view, or the controller? [closed]

Answer 1

According to MVC description,

A controller can send commands to its associated view to change the view's presentation of the model (for example, by scrolling through a document). It can send commands to the model to update the model's state (e.g. editing a document).

According to this, sorting logic belongs in the controller, because altering the way the model data is sorted falls squarely into the "change the view's presentation of the model" category.

EDIT: To clarify multiple misunderstandings voiced in the comments, the "sorting logic" is not the code that performs the sort; it is the code that defines the sort. The sorting logic compares individual items to each other to establish an order (e.g through an instance of IComparator<T>) or contains logic that constructs an object to be used for ordering by an external system (e.g. through an instance of IOrderedQueryable<T>). This logic belongs in your controller, because it needs knowledge related to the "business" side of your application. It is entirely sufficient to perform the sort, but it is separate from the code that actually performs it. The code that sorts may be in your view, in your model, or even in the persistence layer that backs your model (e.g. your SQL database).

Answer 2

(Note: this quote and citation is taken from @dasblinkenlight's answer, but we disagree on our interpretation of it. read his post and make up your own mind).

According to MVC description,

A controller can send commands to its associated view to change the view's presentation of the model (for example, by scrolling through a document). It can send commands to the model to update the model's state (e.g. editing a document).

Sorting logic (e.g., the sorting comparator/sorting algorithm) belongs in the model since it contains business rules and state data. Since altering the way the model data is sorted falls squarely into the "change the view's presentation of the model" category, the controller is responsible for "doing the sorting" by calling the model.changeSortedState() method.

Answer 3

• Views are the part of MVC which is supposed to contain presentation logic.
• Model layer is where business logic is contained.
• Controllers only change the state of both, based on user input.

So the choice is - do you think that this is part of the domain business logic or presentation logic.

If you were implementing a proper MVC Model2 or classical MVC pattern, then I would say that the ordering of data provided by the model layer should be triggered by the view's request to the model layer. View asks for ordered data, model layer provides it.

But, since you are using ASP.NET MVC's interpretation of MVC pattern, which is a bit different then your standard MVC - the ViewModel instance should request ordered information from the model layer (for some reason ASP.NET framework thinks that templates should be called "views" and views should be called "viewmodels" .. it's strange).

Answer 4

This is a question asked with the asp.net in mind, but since somebody did mention Rails, I thought it would be interesting to consider the problem in that context. In Rails, it is natural and pretty common to perform the sorting along with the retrieval as a controller action, since the framework and ActiveRecord/ActiveQuery api provisions for it. On the other hand, it is possible to define some sort of custom sort order for static items and put that in the model to be used by the controller, so the model can play a part in the sorting logic even though it does not carry out the operation directly. Whatever it is, it can be safe to say that putting the sort logic in the view is generally frown upon.

I'm slightly amused that some answers are absolutely against putting the sort in either the controller or the model, and I find them too pedantic for my taste, but I suppose it depends on the nature of the framework used and the usual conventions associated with it. I also agree with Bill K's comment that having the separation in the first place is more important.

Answer 5

None of the above. Sorting is business logic, and business logic doesn't belong in any of the three. Not every piece of code in your application will be a model, view, or controller.

What I generally do in my MVC apps is I have a service layer that performs all the business logic. The methods in the service layer should have a clean, simple API with well named parameters. You can then invoke those methods from your controller to manipulate the data in the models.

In that sense, the sorting is "in the controller", but the code itself that does the sorting should not be implemented in the controller, only invoked from there.

Answer 6

Definetly not the controller: It sends messages to view and model but should do as little work as possible. If the user can change the sorting that request gets handled by the controller by informing the model or the view about it.

Maybe the View if it is a pure View thing. If the Application works just as well without sorting then the sorting is just part of the representation and should go in the view.

If the ordering is inherent part of the domain it should go in the model.