OO approach to form validation

reeksy

I’m slowing getting used to the OO way of thinking! My recent conquest is to incorporate form validation into an OO project. Form validation is usually a repetitive task, so I want to do something about it!

To summarise before I go into too much detail; I’m unsure how to arrange my classes so that they can easily send posted form data to a form validation class.

I work with a lot of forms and therefore I want to be able to send posted form data from one class to another. Once this class validates the variables it can then return a value (to the original class) as to whether the form validation was successful or not.

Here’s a classic example:

Client class (handles login): sends the posted data to a form validation class.
Form validation class: validates data and sends it back.

I don’t want to have to constantly extend the form validation class so I’m thinking that maybe a static class is the way to go? Also I want the form validation class to be as generic as possible as it will deal with a lot of different forms.

Has anyone come across this issue before or does anyone have any ideas?

Jon.

jdorsch

There are a lot of ways to do this. How I do it is I have two validation objects, one is static and called Validate, the other is concrete and called Validator. Validate is just a whole bunch of validation methods and I keep adding to it. I keep it separate because sometimes I want to validate something quickly in code so I just call a static method.

My stuff is setup so that I have one validator for each input field, and each field is its own class, here is how I would set it up if it was outside a class.

// This is all in php5 and the class uses __get and __set
$val = new Validator() ;
$val
  ->required
  ->max_length(15)
  ->min_length(5)
  ->alphanumeric
  ->errorMsg( 'Your password sucks' ) ;

if( !$val->test( $_POST['password'] ) )
{
  echo $val->getError() ;
}

// Do a quick test using the static class that holds the tests
if( !validate::alphanumeric( $_POST['password ) ).....

I use a field collection but if you aren't using objects for form generation then you can create some sort of validation collection and add rules to it, maybe like


$val = new ValidationThingy() ;

// Add a rule for a value in the array named 'password'
$val->addRule('password')
  ->required
  ->max_length(15)
  ->min_length(5)
  ->alphanumeric
  ->errorMsg( 'Your password sucks' ) ;

// Set the array to test
$val->setVars( $_POST ) ;

// Tell the object to loop through every rule and test matching objects
// from $_POST
if( !$val->validate() )
{
  print_r($val->getErrors()) ;
}

Again, there are a lot of ways to do this, the right way depends on your style and how your existing classes are setup, so you don't have to do it this way (which some others think is nuts).

Edit: You can view the source for all of this by viewing the source of database abstraction layer at lawngnome.tigris.org (just check the source out of SVN). FYI the documentation that is on the homepage is out of date and I have only commented about half of lawngnome, but the validation part of it is rock solid.