Form Validation Class using PHP 5.3

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Posted on : 18-06-2010 | By : Brett | In : PHP, Programming

Currently, I am working on a minimal MVC framework for a somewhat ambitious project. I chose to host this website using the latest and greatest: PHP-FPM on nginx running PHP 5.3. After realizing that I needed a form validation library, I came up with one that is fairly easy to use and somewhat extensible. This is the first time I have been able to use Closures in PHP code so maybe I am just a little bit geeky-giddy.

The Code

My only real criteria when I began writing is that I wanted to use method chaining so I could “stack up” rules on a given post variable. Here is what I ended up with:

?View Code PHP
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<?php class FormValidator {
 
    private $messages = array();
    private $errors = array();
    private $rules = array();
    private $fields = array();
    private $functions = array();
    private $haspostdata = FALSE;
 
    public function  __construct() {
        $this->haspostdata = ( $_SERVER['REQUEST_METHOD'] === 'POST' ) ? TRUE : FALSE;
    }
 
 
    /*** ADD NEW RULE FUNCTIONS BELOW THIS LINE ***/
 
    /**
     * email
     * @param string $message
     * @return FormValidator
     */
 
    public function email($message='')
    {
        $message = ( empty ($message) ) ? '%s is an invalid email address.' : $message;
        $this->set_rule(__FUNCTION__, function($email) {
            return ( filter_var($email, FILTER_VALIDATE_EMAIL) === FALSE ) ? FALSE : TRUE;
        }, $message);
        return $this;
    }
    /**
     * required
     * @param string $message
     * @return FormValidator
     */
 
    public function required($message='')
    {
        $message = ( empty ($message) ) ? '%s is required.' : $message;
        $this->set_rule(__FUNCTION__, function($string) {
            return ( empty ($string) ) ? FALSE : TRUE;
        }, $message);
        return $this;
    }
 
    /**
     * numbersonly
     * @param string $message
     * @return FormValidator
     */
    public function numeric($message='')
    {
        $message = ( empty ($message) ) ? '%s must consist of numbers only.' : $message;
        $this->set_rule(__FUNCTION__, function($string) {
            return ( preg_match('/^[-]?[0-9.]+$/', $string) ) ? TRUE : FALSE;
        }, $message);
        return $this;
    }
 
    /**
     *
     * @param int $len
     * @param string $message
     * @return FormValidator 
     */
    public function minlength($minlen, $message='')
    {
        $message = ( empty ($message) ) ? '%s must be at least ' . $minlen . ' characters or longer.' : $message;
        $this->set_rule(__FUNCTION__, function($string) use ($minlen) {
            return ( strlen(trim($string)) < $minlen ) ? FALSE : TRUE;
        }, $message);
        return $this;
    }
 
    /**
     *
     * @param int $len
     * @param string $message
     * @return FormValidator
     */
    public function maxlength($maxlen, $message='')
    {
        $message = ( empty ($message) ) ? '%s must be no longer than ' . $maxlen . ' characters.' : $message;
        $this->set_rule(__FUNCTION__, function($string) use ($maxlen) {
            return ( strlen(trim($string)) > $maxlen ) ? FALSE : TRUE;
        }, $message);
        return $this;
    }
 
    /**
     *
     * @param int $len
     * @param string $message
     * @return FormValidator
     */
    public function length($len, $message='')
    {
        $message = ( empty ($message) ) ? '%s must be exactly ' . $len . ' characters in length.' : $message;
        $this->set_rule(__FUNCTION__, function($string) use ($len) {
            return ( strlen(trim($string)) == $len ) ? TRUE : FALSE;
        }, $message);
        return $this;
    }
 
    /**
     *
     * @param string $field
     * @param string $label
     * @param string $message
     * @return FormValidator
     */
    public function matches($field, $label, $message='')
    {
        $message = ( empty ($message) ) ? '%s must match ' . $label . '.' : $message;
 
        $matchvalue = $this->getval($field);
 
        $this->set_rule(__FUNCTION__, function($string) use ($matchvalue) {
            return ( (string)$matchvalue == (string)$string ) ? TRUE : FALSE;
        }, $message);
        return $this;
    }
 
    /*** ADD NEW RULE FUNCTIONS ABOVE THIS LINE ***/
 
    /**
     * callback
     * @param string $name
     * @param mixed $function
     * @param string $message
     * @return FormValidator
     */
 
    public function callback($name, $function, $message='')
    {
        if ( is_callable($function) ) {
            // set rule and function
            $this->set_rule($name, $function, $message);
        } elseif ( is_string($function) && preg_match($function, 'callback') !== FALSE ) {
            // we can parse this as a regexp. set rule function accordingly.
            $this->set_rule($name, function($value) use ($function) {                
                return ( preg_match($function, $value) ) ? TRUE : FALSE;
            }, $message);
        } else {
            // just set a rule function to check equality.
            $this->set_rule($name, function($value) use ( $function) {
                return ( (string)$value === (string)$function ) ? TRUE : FALSE;
            }, $message);
        }
        return $this;
    }
 
    /**
     * validate
     * @param string $key
     * @param string $label
     * @return bool
     */
 
    public function validate($key, $label='')
    {
        // do not attempt to validate when no post data is present
        if ( $this->haspostdata ) {
            // set up field name for error message
            if ( !empty ($label) ) {
                $this->fields[$key] = $label;
            }
            // try each rule function
            foreach ($this->rules as $rule => $is_true) {
                if ( $is_true ) {
                    $function = $this->functions[$rule];
                    if ( is_callable($function) ) {
                        if ( $function($this->getval($key)) === FALSE ) {
                            $this->register_error($rule, $key);
                            // reset rules
                            $this->rules = array();
                            return FALSE;
                        }
                    }
                }
            }
            // reset rules
            $this->rules = array();
        }
    }
 
    /**
     * has_errors
     * @return bool
     */
 
    public function has_errors()
    {
        return ( count($this->errors) > 0 ) ? TRUE : FALSE;
    }
 
    /**
     * set_error_message
     * @param string $rule
     * @param string $message
     */
 
    public function set_error_message($rule, $message) {
        $this->messages[$rule] = $message;
    }
 
    /**
     * get_error
     * @param string $field
     * @return string
     */
 
    public function get_error($field)
    {
        return $this->errors[$field];
    }
 
    /**
     * get_all_errors
     * @return array
     */
 
    public function get_all_errors()
    {
        return $this->errors;
    }
 
 
    /**
     * getval
     * @param string $key
     * @return mixed
     */
 
    private function getval($key)
    {
        return ( isset ($_POST[$key]) ) ? $_POST[$key] : FALSE;
    }
 
    /**
     * register_error
     * @param string $rule
     * @param string $key
     */
 
    private function register_error($rule, $key)
    {
        $message = $this->messages[$rule];
        $field = $this->fields[$key];
 
        if ( empty ($message) )
            $message = '%s has an error.';
 
        if ( empty ($field) )
            $field = "Field with the name of '$key'";
 
        $this->errors[$key] = sprintf($message, $field);
    }
 
    /**
     * set_rule
     * @param string $rule
     * @param closure $function
     * @param string $message
     */
 
    private function set_rule($rule, $function, $message='')
    {
         // do not attempt to validate when no post data is present
        if ( $this->haspostdata ) {
            if ( ! array_key_exists($rule, $this->rules) ) {
                $this->rules[$rule] = TRUE;
                if ( ! array_key_exists($rule, $this->functions) && is_callable($function) ) {
                    $this->functions[$rule] = $function;
                }
                if ( !empty ($message) ) {
                    $this->messages[$rule] = $message;
                }
            }
        }
    }
 
}
?>

Please note: This only works for forms submitted with POST. However, it can be easily modified to work with GET also.

Usage

Now, let’s say that I have a form and I want to validate an email field and set up a password. The password must be at least 10 characters and the password confirmation field must match the password field. On top of that, I have a simple captcha where I just ask the user to add two integers that equal 10. With my class, I only need to write the following code:

?View Code PHP
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$formval = new FormValidator();
 
$formval->required()->email()->validate('email', 'Email Address');
$formval->required()->minlength(10)->validate('password', 'Password');
$formval->required()->matches('password', 'Password')->validate('password2', 'Password Confirmation');
 
$formval->required()->callback('captcha', function($value) {
    return ( preg_match('/^\d\s*\+\s*\d$/', trim($value)) && eval ($value) == 10 ) ? TRUE: FALSE;
}, '%s does not add up to 10!')->validate('captcha', 'Captcha');
 
if ( $formval->has_errors() ) {
   print_r($formval->get_all_errors());   
} else {
    // submit the form!
}

Pretty simple!

I have not started using this class heavily ( I just finished it) so let’s call it alpha code for now.

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