updating from PHP 7.4 to 8.1: call to a member function () on null

wkilc · August 12, 2022

Hello.

Despite being at this for a while, I am in reality a grade-school teacher and a PHP novice.

I have a third-party PHP form mail script that I purchased years back. The company is in the Ukraine and appears to no longer be in business. (God Bless.)

Anyway, the script always appeared to work perfectly with PHP 7.4. I set my site to 8.1 to test it out... saw a few minor warnings that even I could pretty easily remedy. However, there's one that has me stumped.

Fatal error: Uncaught Error: Call to a member function setContent() on null in /home/www/www/fp/classes/outputer.class.php:53 Stack trace: #0 /home/www/www/fp/classes/outputer.class.php(92): Outputer->output('<!DOCTYPE HTML ...') #1 /home/www/fp/ptd.php(93): Outputer->showDefaultPage() #2 {main} thrown in /home/www/www/fp/classes/outputer.class.php on line 53

I believe that this is the part of the form that processes form data and then outputs it to a HTML page template to show the results of the submission.

Line 53:

$this->response->setContent($content);

Line 93:

$this->output($content);

The code surrounding line 53:

function output($content, $isError = false){
    	    if ($isError){
    	    	$request = $this->getRequestData();
    	    	$this->response->setOuputOffset($request['fpp_output']);
    	    }    
            $this->response->setContent($content);
            $this->response->printOut();
		}
    	function redirect($url){
            if (function_exists('ob_start')){
            	ob_start();
            	ob_clean();
            }
            
            header('Location: ' . $url);
            exit();
    	}
    	
		/**
		 * Shows default page

I've been researching this and I realize this is likely a result of a value of "null" coming up... but everything I've tried to remedy doesn't help.

Again, rolling site back to 7.4 and everything works as it should, no errors or warnings.

Many thanks for any guidance you can provide.

Edited August 12, 2022 by wkilc

ginerjm · August 12, 2022

Whatever has created the reference to $this has not set it to something of that class. That's what the message is telling you. Basically $this or $this->response does not exist.

wkilc · August 12, 2022

Thank you. My problem is I have don't know how to remedy that.

I tried:

$this->response=new response();

That removes in fact removes the error, but then the form data won't get outputted to the HTML template.

mac_gyver · August 12, 2022

i suspect the code has a method with the same name as the class, where the initialization is/was occurring. such a method no longer gets called automatically when an instance of the class is created. you must specifically supply a __construct() method.

wkilc · August 12, 2022

Thank you. Forgive me for asking, but could you possibly show me where in my code to add construct() so I could try it out?

Or have I not posted enough to go there?

mac_gyver · August 12, 2022

it would take having the entire class definition to determine if this is the cause.

ginerjm · August 12, 2022

The new version of php requires a class definition to use a different method of creating/initializing/instantiating a class. The old way was to use the class name in a call to create a 'new' class which executed a method by that name. Now you must use a method named '__construct' to create a new one. You will have to look at your class definition for the method using the class's name and rename that as __construct.

wkilc · August 12, 2022

Thank you. Like this?

__construct() {

$this->response->setContent($content));

}

Here's the rest of the outputter file:

    	function Outputer(){
    		global $response;
    		
    	    $this->response = $response;
    	    $this->setType(ACTION_TYPE_OUTPUTER);
    	    return true;
    	}
    	
    	/**
    	 * Does contents output
    	 *
    	 * @param string $content
    	 * @return void
    	 */
    	function output($content, $isError = false){
    	    if ($isError){
    	    	$request = $this->getRequestData();
    	    	$this->response->setOuputOffset($request['fpp_output']);
    	    }    
            $this->response->setContent($content);
            $this->response->printOut();
		}
    	function redirect($url){
            if (function_exists('ob_start')){
            	ob_start();
            	ob_clean();
            }
            
            header('Location: ' . $url);
            exit();
    	}
    	
		/**
		 * Shows default page
     	 *
     	 * @return void
     	 */
    	function showDefaultPage(){
    		global $lang;
    		$lang		= new Lang();
    		
    		$content  = '';
    		$content .= '<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.01 Transitional//EN"'."\n";
   			$content .= '"http://www.w3.org/TR/html4/loose.dtd">'."\n";
    		$content .= '<html>';
			$content .= '<head>';
			$content .= '<title>' . $lang->getValue('default_page_title') . '</title>';
			$content .= '</head>';
			$content .= '<body bgcolor="#FFFFFF" text="#000000" link="navy" vlink="navy" alink="red" style="font-family: verdana, arial, sans-serif; font-size: 8;">';
			$content .= '<center><table border="0" cellpadding="0" cellspacing="0" width="600" style="font-family: verdana, arial, sans-serif; font-size: 12;">';
  			$content .= '<tr><td>';
        	$content .= '<p align="center">' . $lang->getValue('default_page_content') . '</p>';
        	$content .= '<p align="center">' . $lang->getValue('default_page_footer') . '</td>';
  			$content .= '</tr>';
			$content .= '</table>';
			$content .= '</center>';
			$content .= '</body>';
			$content .= '</html>';
    	    $this->output($content);
    	}    	
    }

ginerjm · August 12, 2022

Your construct is using a variable that is not defined with an argument in the method's header. Was the original just like that?

wkilc · August 12, 2022

I don't know enough to follow these suggestions. I am sorry.

In the main index.php file for this script, it has:

    /**
     * Path definitions
     */
    define('PLUGINS_DIR',    './plugins/');
    define('CLASSES_DIR',    './classes/');
    define('CONFIG_FILE',    './ptd_config.php');
    define('ATTACHMENT_DIR', './attachments/');
    define('LANGUAGE_DIR',	 './lang/');
    define('TMP_DIR',	 	 './tmp/');
    
    /**
     * Default language definition
     */
    define('DEFAULT_LANG',	 'en');
    
    /**
     * Loading common classes
     */
    require_once(PLUGINS_DIR . 'common.php');
    require_once(CLASSES_DIR . 'error.class.php');
    require_once(CLASSES_DIR . 'file.class.php');
    require_once(CLASSES_DIR . 'config.class.php');
    require_once(CLASSES_DIR . 'lang.class.php');
    require_once(CLASSES_DIR . 'request.class.php');
    require_once(CLASSES_DIR . 'response.class.php');
    require_once(CLASSES_DIR . 'action.class.php');
    require_once(CLASSES_DIR . 'validator.class.php');
    require_once(CLASSES_DIR . 'executor.class.php');
    require_once(CLASSES_DIR . 'outputer.class.php');
    require_once(CLASSES_DIR . 'parser.class.php');
    require_once(CLASSES_DIR . 'formerror.class.php');

    /**
     * Main classes construction
     */
    $lang		= new Lang();
    $config		= new Config();
    $formError	= new FormError();
    $request	= new Request();
    $response	= new Response();


    if (isset($_POST['fpp_reset'])) {
    	$request->data['fpp_form'] = trim($_POST['fpp_form']);
    	$request->data['fpp_output'] = 1;
    }
    
    /**
     * Checking writable dirs
     */
    if (!is_writable(ATTACHMENT_DIR)){
    	$e = new Error($lang->getValue('err_dir_not_writable', ATTACHMENT_DIR));
    }
	if (!is_writable(TMP_DIR)){
    	$e = new Error($lang->getValue('err_dir_not_writable', TMP_DIR));
    }

Is this where the changes need to be made?

kicken · August 12, 2022

Change this

function Outputer(){

To this

function __construct(){

See if that fixes the issue.

wkilc · August 13, 2022

Thank so much! That does indeed squash the error... but now with PHP 8, the form outputs simply:

default_page_content

default_page_footer

rather than the HTML form template that loads when processing with PHP 7.4.

kicken · August 13, 2022

There may be other classes that need the same fix, but aren't broken enough to cause an error. Look in the other PHP files for classes which have a function with the same name as the class, for example:

class MyFancyClass {
    function MyFancyClass(){
        //stuff
    }
}

Then rename the method to __construct like you did before so the code would become:

class MyFancyClass {
    function __construct(){
        //stuff
    }
}

If you can't find any or fixing the remaining ones doesn't resolve the problem then you may have some other compatibility issue.

That the code has this particular issue indicates is was probably written around the PHP 4 / early PHP 5 days. Much has changed since then, so you'll likely have to do one of

Spend time learning and fixing the issues or
Hire someone to fix the scripts for you or
Find a newer up to date script that does the same thing.

mac_gyver · August 13, 2022

it's also possible that the method in question is being explicitly called from somewhere within the code, given that it returns a value. there would be a fatal error, which could be hidden in the 'view source' of the output or may be hidden due to php's error_reporting/display_errors settings.

if this is the case, you would need to keep the original outputter() method definition, then have the new __construct() method call the outputter() method.

wkilc · August 13, 2022

Thank you.

I took ginerjm's advice from his signature and enabled ALL errors and found that while it worked in PHP 7.4 there were deprecated issues... I will start there.

Deprecated: Non-static method Action::isAvailable() should not be called statically...

Deprecated: Non-static method Action::Factory() should not be called statically...

...both appear 7 or 8 times, always point to the same line.

The former:

if (Action::isAvailable($var['name'])) {

This is the latter one:

$action = Action::Factory($action_data['name']);

I actually hired a Freelancer to try to fix the scripts a few days ago but we were not able to. Although, from what I've learned from this thread, along with all those new warnings from 7.4 and I think we'd have a better chance if we have another go at it.

Edited August 13, 2022 by wkilc

mac_gyver · August 13, 2022

it you post all this code on github, less any private settings, someone can have a look at it.

things that were previously Deprecated and have been removed in php8 will be producing errors, though if the code is running to the point of producing output, they are at least non-fatal errors. if the code itself is setting the error related settings, anything you do to set them, might be overwritten.

this looks like a typical misuse of OOP and from the small amount of actual posted logic, the author(s) misunderstood some of how php even works (the output buffering code in the redirect method does absolutely nothing.) this is a form to email application. are you using multiple user languages? are you using file attachments? it doesn't actually take a lot of code to validate a form submission and send an email.

Edited August 13, 2022 by mac_gyver

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updating from PHP 7.4 to 8.1: call to a member function () on null

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