Non-static method AJAXChatFileSystem::getFileContents() should not be called statically

I am setting up Ajax-Chat in my Apache Server (2.4) with PHP 7 but I am getting this error

Deprecated: Non-static method AJAXChatFileSystem::getFileContents() should not be called statically in C:\Apache24\htdocs\services\chat\lib\class\AJAXChatTemplate.php on line 37

I tried changing function getContent() to public static function getContent() but after that it's showing:

Fatal error:Uncaught Error: Using $this when not in object context in C:\Apache24\htdocs\services\chat\lib\class\AJAXChatTemplate.php:36

class AJAXChatTemplate {

    var $ajaxChat;
    var $_regExpTemplateTags;
    var $_templateFile;
    var $_contentType;
    var $_content;
    var $_parsedContent;

    // Constructor:
    function __construct(&$ajaxChat, $templateFile, $contentType=null) {
        $this->ajaxChat = $ajaxChat;
        $this->_regExpTemplateTags = '/\[(\w+?)(?:(?:\/)|(?:\](.+?)\[\/\1))\]/se';
        $this->_templateFile = $templateFile;
        $this->_contentType = $contentType;
    }

    function getParsedContent() {
        if(!$this->_parsedContent) {
            $this->parseContent();
        }
        return $this->_parsedContent;
    }

     function getContent() {
        if(!$this->_content) {
            $this->_content = AJAXChatFileSystem::getFileContents($this->_templateFile);
        }
        return $this->_content;
    }
}

Solution

Calling a non-static method statically in PHP is deprecated behaviour since version 7.0 and raises an E_DEPRECATED warning. This means that support for this behavour works, but may (and probably will) be removed in a future version.

This behaviour raised an E_STRICT warning in PHP versions 5.*.

Changing your own AJAXChatTemplate::getContent() method to static does not work because it uses $this which only makes sense in the context of an instance of a class. Therefore it triggers a fatal error in a static context.

You are using the AJAX-Chat library—you haven't stated what version you are using but there is an issue that discusses the error you encounterd.

In line with this reported issue, a commit to recent versions of this library were made to change this a static behaviour.

To resolve your issue, you have two choices:

Continue to use the version of AJAX-Chat that you have currently installed

Just use the AJAXChatFileSystem::getFileContents() non-statically. Create an instance of the class and use that by modifying your getContent() method like so:

function getContent()
{
    if (!$this->_content) {
        $ajaxChatFileSystem = new AJAXChatFileSystem(); 
        $this->_content = $ajaxChatFileSystem->getFileContents($this->_templateFile); 
    }

    return $this->_content;
}

Upgrade to the latest version of this library and use the static method

There does not appear to be a changelog, so you should test your code wherever you use AJAX-Chat to ensure there are no breaking changes.

Technically, you have a third choice: since this is an E_DEPRECATED warning—implying that the functionality is flagged for removal at a future date—you can safely ignore this warning, for now.

E_DEPRECATED warnings (as with all notices, warnings and errors) should be disabled from display to the user in production code.

However, I do not recommend this because your logs will be full of E_DEPRECATED warnings. Moreover, as already mentioned, future versions of PHP may remove support for calling non-static methods statically.

Hope this helps :)