Kohana ORM & MVC

Question

although I am pretty decent at PHP I am new to frameworks. started with CI last week and found myself looking at Kohana this week. I have few questions to that regard:

1. why ORM vs traditional SQL or active queries?
2. if the model must fetch data from DB , how come in ORM most of the action happens in the controller ( or so it seems ) ie ( $data=$q->where('category', '=', 'articles')->find_all();}
3. how would I do a conditional query in ORM? ( something like if (isset($_GET['category']))...etc ) if the condition is passed to the model? or should the controller do all the conditions

FYI my queries tend to have numerous joins and my limited knowledge tells me that I should have a query controller that passes queries parameters to a query model which does the query and returns results. Please let me know if my understanding is correct thank you very much

Answer 1

1. ORM is just another way to get at your data. The idea is that there are many common kind of operations, and that could be automated. And because the relations between tables can easily be translated to objects referencing eachother, ORM was created.

   It's up to you if you want to use the supplied ORM module. There are others which are also commonly used (like sprig, jelly and auto-modeler).

2. My personal opinion is to limit that kind of operations to a minimum. Very simple operations can be done this way, because it barely produces any advantages in placing them in the model, but the best way is to try to put the business logic as much in the models as possible.

   Another point is that it should be the view that gets the data from the models. That way, when you want to reuse a view, very little code has to be duplicated. But to prevent too much logic getting in your views, it's recommended to use so-called viewclasses which contain the logic for your views, and is the interface for your views to talk to.

3. There is a Validation library to make sure that all the data for your model is correct. Your models shouldn't know about $_GET and $_POST, but the data from those arrays can be passed to your models.

Answer 2

1. ORM is some kind of wrapper over the DB layer. So, you just call $user->find($id) instead of $db->query('select * from users where id='.$id) or DB::select()->from('users')->where('id', '=', $id)->limit(1)->execute(). You declare model params (table name, relations etc) and use only model methods to work with its data. You can easily change DB structure or DB engine without modifying a lot of controller code.

2. Agree with Ikke, controller should avoid model specific data like query conditions. For example, create method get_by_category($category).

3. See #2. All args you want should be passed into model method (this can be done using chaining, like $object->set_category($category)->set_time_limit(time())->limit(10)).