hi all
i have been trying to implement a plugin/hook system in my own cms creation.
i have been following a short tutorial and have managed to get it to work for one
plugin but after that i am getting.
Undefined index: errors. i believe this is because i really dont understand what is happening around the mysql SELECT query.
i dont understand how the array of results is converted to the object format that is used just after. the writer has created a function ($mysqlConnection->resultToObjects) that seems to convert the results of the SELECT * query into a nice format to work with.
im sure its not all that complicated but i just need someone to point out what is happening here and perhaps suggest some code for me to try.
thank you so much in advance.
// This bit checks if we are currently
// running inside our website. It prevents
// from overly curious people to launch
// this php file from outside of our script
if( !defined( "INPROCESS" ) ){
header("HTTP/1.0 403 Forbidden");
die();
}
// Those two are classes that I wrote
// to simplify access to mysql and other
// databases. You will have to delete those
// two lines, and write your own code
// to access mysql
require_once( 'data.class.php' );
require_once( 'data.mysql.class.php' );
// This is the parent class for all plugins
// It contains a private constructor, that
// basically makes sure we won't have any
// instances of our static classes. Making
// them completely static.
class plugin{
private function __construct(){}
}
// This is the actual plugin class.
class pluginClass{
// This will be the list of active plugins
static private $plugins = array();
// Again, we don't want any instances
// of our static class.
private function __construct(){}
static function initialize(){
// I have those variables elsewhere in
// a config.php file. you can replace
// those with your own
global $config_fullpath;
global $config_username;
global $config_password;
global $config_server;
global $config_database;
$list = array();
// Populate the list of directories to check against
if ( ($directoryHandle = opendir( $config_fullpath . '/plugins/' )) == true ) {
while (($file = readdir( $directoryHandle )) !== false) {
// Make sure we're not dealing with a file or a link to the parent directory
if( is_dir( $config_fullpath . '/plugins/' . $file ) && ($file == '.' || $file == '..') !== true )
array_push( $list, $file );
}
}
// Get the plugin list from MySQL. Note that you will have to replace
// this code with your own, since I'm using classes that I didn't
// include in this article. Fortunately, it won't be too much of a problem.
// Connect to mysql
$mysqlConnection = new mysqlConnection( $config_username, $config_password, $config_server, $config_database );
// We select all the plugins from our database
// Each plugin has it's name stored, and whether
// it is active or not (active = 0 or 1)
$mysqlConnection->prepareQuery( 'SELECT * FROM plugins' );
$results = $mysqlConnection->executeQuery();
$results = $mysqlConnection->resultToObjects( $results );
[COLOR="Red"]//this is where i am stuck. i dont understand what the resultToObjects function
//would do (above ). or how i can get the results from the database to be in the format as
// used below. ie [$result->name]= $result->active; [/COLOR]
$newResult = array();
// Create an array: 'plugin name' = 'active' (1 or 0)
foreach ( $results as $result ){
$newResult[$result->name] = $result->active;
}
// Register the active plugins
foreach( $list as $plugin ){
if($newResult[$plugin] == "1"){
pluginClass::register( $plugin );
}
}
}
// Hook the active plugins at a checkpoint.
// You will see exactly how it works later on.
static function hook( $checkpoint ){
// Cycle through all the plugins that are active
foreach(pluginClass::$plugins as $plugin){
if(!call_user_func( array( $plugin, $checkpoint ) ))
// Throw an exception if we can't hook the plugin
throw new Exception( "Cannot hook plugin ($plugin) at checkpoint ($checkpoint)" );
}
}
// Registration adds the plugin to the list of plugins, and also
// includes it's code into our runtime.
static function register( $plugin ){
global $config_fullpath;
require_once( $config_fullpath . "/plugins/$plugin/$plugin.class.php" );
array_push( pluginClass::$plugins, $plugin );
}
}
index.php
// Tell the class it is safe to run
define( "INPROCESS", true );
// My configuration file
require_once( './config.php' );
// Our plugin class
require_once( './include/plugin.class.php');
// Initialize our plugin engine
pluginClass::initialize();
// Create a new hook point called "onLoad"
// Now all the plugins that can be hooked here
// will be ran.
pluginClass::hook( "onLoad" );
A Sample Plugin
A sample plugin will reside in it's own directory inside plugins/. For example plugins/helloworld/. Then we need to go (or have a script that does it automatically. Homework for you...) to our database and add it, with its name there and active = 1. That's it, we're done with installing our plugin!
plugins/helloworld/helloworld.class.php
if( !defined( "INPROCESS" ) ){
header("HTTP/1.0 403 Forbidden");
die();
}
// We inherit the parent class plugin to make sure we will have no accidental instances of this class.
class helloworld extends plugin {
// That's right. We create a function with the name
// of our hook, and walla! We have a plugin hooked at
// onLoad.
static function onLoad(){
print 'Hello World!';
return true;
}
}
