How is MVC supposed to work in CodeIgniter

Question

As a mostly self-taught programmer I'm late to the game when it comes to design patterns and such. I'm writing a labor management webapp using CodeIgniter.

I did a bit of MVC ASP.NET/C# and Java at school, and the convention was that your model mainly consisted of classes that represented actual objects, but also abstracted all the database connection and such...which is pretty standard MVC stuff from what I've gathered.

I imagine I'm right in saying that CI abstracts the database connection completely out of sight (unless you go looking), which is par for the course, and the models you can create can abstract the 'generic' CRUD methods a bit more to create some methods that are more useful for the specific model.

The thing I have a problem with, because it's different to what I'm used to with MVC, is that whenever you say...return a row from a database, the convention is to just put it in an associative array or standard object with the properties representing the data from the row.

In ASP you'd have actual classes that you could construct to store this information. For example you'd have a House class and the data would be stored as properties (e.g. bedrooms, bathrooms, address) and the methods would represent useful things you could do with the data (e.g. printInfo() may print("$address has $bedrooms bedrooms and $bathrooms bathrooms!')).

I'm getting the impression — just from code I've seen around the Internet — that this isn't the standard way of doing things. Are you supposed to just use arrays or generic objects, and say...do $this->house_model->print_info($houseobject) instead of $houseobject->print_info();?

Thanks.

Answer 1

Despite its claims to the contrary, Codeigniter does not use MVC at all (In fact, very few web frameworks do!) it actually uses a PAC (Presentation-abstraction-control) architecture. Essentially, in PAC the presentation layer is fed data by a presenter (which CodeIgniter calls a controller) and in MVC the View gets its own data from the model. The confusion exists because of this mislabeling of MVC.

As such, CodeIgniter (and most of the other popular web frameworks) don't encourage a proper model but just use very rudimentary data access its place. This causes a large set of problems because of "fat controllers". None of the code which relates to the domain becomes reusable.

Further reading:

• MVC vs. PAC

• The M in MVC: Why Models are Misunderstood and Unappreciated

• Model-View-Confusion part 1: The View gets its own data from the Model

• The Fat Controller

This is a widespread point of confusion in the PHP Community (The MVC vs. PAC article identifies the problem as stemming from the PHP community. that was written in 2006 and nothing has changed, if anything it's got worse because there are more frameworks and tutorials teaching an erroneous definition of MVC.) and why people looking at "MVC" PHP code who have come from a background outside web development understandably become confused. Most "MVC" implementations in PHP are not MVC. You are correct in thinking models should be properly structured, it's CodeIgniter that's wrong to label itself as MVC.

Answer 2

CodeIgniter is very flexible when it comes to following the MVC pattern and it's really up to you how much you want to enforce it. Most of the CodeIgniter code you will find online is exactly like you describe, the Models are just a collection of methods really, and don't strive to strictly represent an object.

You can, however, code that way too if you so like within CI (and this is something I often do). It makes the code much more maintainable and readable, and just seems better all around.

PS - If you're just getting into MVC in PHP, you might want to look around a little. Frameworks like CodeIgniter and CakePHP are (somewhat) of a previous generation. CI was initially written for PHP4 where OOP support was kinda spotty in PHP. A fork of CI, called Fuel, was specifically created to address this issue (though I believe at some point, they just decided they would be better served by rewriting it from scratch). CI does have the advantage of having a lot of documentation and help online since it is more widely used than Fuel.