CakePHP Fat models and skinny controllers - appModel

Question

In an effort to follow best MVC practices I'm trying to ensure all my code follows the fat model, skinny controlller methodology therefore could someone cast their eye over the below and tell me if I'm on the right track?

Currently in my app I have

ExpenseClaims hasMany Expenses
Expenses belongsTo ExpenseClaims

In my pages/admin_index.ctp I need to get the total of all Expenses belonging to each ExpenseClaim listed.

So, the best FMSC way I can see to do this would be to load the ExpenseClaim model within the AppModel

App::uses('ExpenseClaim', 'Model');

And then have a function within the AppModel that I can use across the apps controllers (because its in the appModel) that I can pass a ExpenseClaim ID to and it will return a total of all related Expenses.

Is this the correct most MVC way of doing it rather than doing it all in the controller?

Thanks in advance

Well ... you are using Cake. That already means that all the MVC-related practices have been thrown out. Since CakePHP is a Rails clone, you should instead focus on practices that are recommended for Rails users. As for your question: it is always good idea to keep any application and/or business logic out of "controller". Unfortunately, since Cake pretends that Model is an ActiveRecord instance, you will still have a lot of application logic in te "controllers". — tereško
I would recommend everyone to make Fat models rather than Fat controller because Fat models make it easier to change business logic wherever the model is used. Models become reusable. On the contrary, Fat Controllers makes it more difficult because business logic is enclosed in the Controller and changes made are not reusable in other controllers. If in case you can’t reduce controller than you need to split business logic in more than one action rather than implementing it in one action. This will ease our life. — Moyed Ansari
Neither of you really answer my question, I know FMSC has benifits which is why I'm trying to follow it and I'm not interested in if the internal workings of cake are not optimal either. — James J

Nunser Nunser · Accepted Answer · 2013-06-19T14:32:18

The best FMSC way is to, as you say, write the function in the model. But!! Don't do it in the AppModel, that's bad practice. Why would you put code related to two (at most) models in the AppModel?? Every model would inherit that function, that doesn't make much sense. Let's say you have a "Menu model" or an "User model", it isn't logical that they inherit a totalExpenses function, right? I understand that you want to have the function available in every controller and view if the need rises, but that's not the way to do it.

Step by step (actually, just two steps):

1) In the ExpenseClaim model, write a new function that will calculate the total of expenses

class ExpenseClaim extends AppModel {
      /* definitions and validations here*/

      public function totalExpenses($id) {
          return $this->Expenses->find('count', array('conditions'=>
                                                   array('expense_claim_id' => $id)));
      }
}

So, in the ExpenseClaimsController you can call this function with

$total = $this->ExpenseClaims->totalExpenses($the_id);

2) Now, it's logical to have the function that counts the total in the expenses claim model, and therefore available in the respective controller, but you said you wanted to use it in pages/admin_index, and let's imagine pages has absolutely no connection with the claim model. Well, then you can either do

ClassRegistry::init("ExpenseClaims")->totalExpenses($the_id);

or

$this->loadModel("ExpenseClaims");
$this->ExpenseClaims->totalExpenses($the_id);

(both in the controller) and you'll have that value available without putting that function in the AppModel.

(Btw, the code I wrote should work, but you need to fine tune the controllers and models names or close a parenthesis here and there, I haven't tested it).

Now, that's general best practice. Works in most cases, with more complicated functions. But for your case in specific, you may want to take a look at cake's counterCache, it keeps count of stuff without you having to do much.

CakePHP Fat models and skinny controllers - appModel

1 Answers