What should go in CodeIgniter models?

I've always used the model as something to more or less store and execute database queries. I have heard about the fat model, thin controller concept.

The way I setup my models right now causes a lot of junk in controllers for things like val开发者_开发问答idating forms, formatting data. Does form validation, file uploading and data formatting belong in the controller or the model?

I realize this question is subjective, which should create some good discussion rather than a concrete answer.

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Form Validation should definitely be part of the model. I generally represent each form as one model and pass it the sanitized post/get paramaters. The model can then take whatever action is necessary based on the input and use a property (optionally with a getter) to signal success or failure. In psuedo code you want it to look something like:

class Controller
{
    function action()
    {
        $input = new Input();
        $form = new FormModel($input);
        if ($errors = $form->errors())
        {
            //load the appropriate view for the errors
        }
        else
        {
            //load the appropriate view for success with an optional redirect
        }
}

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You have two main roads to go. Thin controller/fat model or fat controller/thin model. Basicly is were you put most of the interaction. I prefer to keep at the model the major portion of the code. That way, the code is available in virtually every controller and/or lib. If the code remain at controller, it's hard (but not impossible) to use it in other controllers.

Things lije validations and other common tasks should be in a lib or helper. You can produce a set of "workers" (this is the name I give to them) to do the heavy lifting. Also, CI has a LOT of ready made libs and helpers both from the CI team and the community. Mess around the wiki to find the wealth of information available.

Hope this helps Vx

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The model is what interacts with the data (most often a database). Controllers use the models to access the data.