basic but....

[eluser]nmweb[/eluser]
You pass values to your model, your model should have no knowledge of $_POST nor should it do something with it. Your controller should give the model the values.

(primitive state)

Code:

class Some_Model{
protected $fields=array('email');

protected $validate=array(
'field_name'=>array('rules'=>array('required','email'))
);

public function save()
{
   if($this->validate())
   {
      //db insert here with values from $this->field array
return true;
   }
return false;
}
public function validate()
{ $validate=true;
    foreach($this->fields as $field)
    {
    //iterate over rules and what not
      if(!$this->is_valid($field)
      {
       $validate=false;
      }
    }
   return $validate;
}
public function is_valid($field)
{
//get rules for field and validate it
}
public function get_errors(){}
}

In the model above you can handle form field/db field differences with some property of the object.

Now, what does the controller look like:

Code:

//controller
$model=new Some_Model;
$model->email='some wrong email';
if($model->save())
{
echo 'correct mail';
}
else
{
$model->get_errors();
}

To show how Django handles it and how I plan to handle it:

Code:

//bit of pseudo code
class Email_Form extends Form_generation_class{
   protected $form_fields=array('email);
}

$form=new Email_Form(new Some_Model);
echo $form->render();

That's it. It will generate a form based on the model with proper validation including nice error messages and javascript validation. Say you want to edit an existing record.

Code:

$form=new Email_Form(new Some_Model(10); //record number 10
echo $form->render();
if($form->save()) //validates then tries to save the model
{
}

That's it in a nutshell.