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Asked: 2026-05-20T01:36:56+00:00

I’m using a framework which uses the MVC paradigm. It’s CodeIgniter, but my question

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I’m using a framework which uses the MVC paradigm. It’s CodeIgniter, but my question isn’t about the framework specifically – it’s more generally about best practices when working with MVC.

I’m using $_SESSION variables to maintain some state variables (user selections, some temporary preferences, some data filtering options). This is easy enough to do, but I found that I was splitting the use of these variables across both models and controllers. Sometimes I would update one in a controller, and look it up in a model. This started to “smell” funny, because it occurred to me that it might not be a good idea to make the models “aware” of all those settings. Shouldn’t the models just accept requests for fetching/manipulating data, and only be concerned with what was explicitly in the request (without having to look up external variables)?

Here is an example: I have one session variable called $_SESSION[‘regionFilter’]. This is created and updated in a controller, and represents a sales region the user wants to “drill down” to. When a controller requests some data from a model, I’m currently having the model look up the $_SESSION[‘regionFilter’] variable, and use it when it’s creating its SQL for the database. It seems like it might make more sense to make the model “dumb” regarding program state, and have the controller somehow bundle the $_SESSION[‘regionFilter’] variable into its request if it wants it.

Any thoughts? Thanks!

Edit: Thanks for the discussion, folks. I’m aware of the overlapping questions, but had a hard time finding a general discussion on the topic – my searches for “MVC model program state” turned up slews of questions about ASP.NET-MVC-specific discussions which were mired in implementation details.

I’ve marked the question as closed. Thanks again for your thoughts!

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1 Answer

  1. Editorial Team

    I think you’re quite right in worrying about it smelling funny. You’ve just introduced something that has nothing to do with the model, in to the model.

    I don’t see anything wrong with providing a filter to the model, perhaps something that takes a string that represents your region. If you want to pass the session in to that, then feel free, but by putting the session stuff (even reading) in to the Model, you’ve intrinsically linked the two… A model to a session state.

    Provide a method in the Model that will filter appropriately, and then by all means pass in a session variable from the controller, but the model has no idea that the filter came from the session variable. It’s just a filter.

    EDIT: To clarify, I’d say that session state is part of the controller, definitely not the model.

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