Question

What does the trim form validation rule actually do and when should I use it?

Thanks

Answer 1

It removes whitespace from the beginning and end of an input string.

You can think of validation rules as a pipeline of routines run on the input. For example :

$this->form_validation->set_rules('email', 'email', 'trim|required|valid_email');

When validating the email input CodeIgniter :

1. Removes whitespace from the beginning and end of the string
2. Checks that the resulting string is non-empty
3. Checks that it is a valid email address

The trim routine is normally run before other routines and placed at the front of the list.

You should use it when you want to ignore the starting and trailing whitespace in the input. Perhaps the user has accidentally typed a space character after an email address in a HTML form. The space character should not be taken as part of the email address and should be removed.