Question

Sometime I have to use include_once and include it depend how the page are accessed. For example:

sales.php

include("class/pdoDatabase.php");
include("class/ClassExample.php");

$obj = new ClassExample();
$obj->getNewItem(1);

ClassExample.php

include_once("class/pdoDatabase.php");

class ClassExample {
  public function  getNewItem($id) { .. }
   public function addNew($id) { .. }
}

// Accessing this file directly via Ajax request 
if (isset($_POST['AddNew'])) {
   $obj = new ClassExample ();
   $obj->addNew($_POST['id']);
 }
}

If you access to sales.php which will then load include("class/ClassExample.php");, however I have to use include_once in the ClassExample.php because pdoDatabase.php might be already loaded in sales.php.
If you access the file directly to ClassExample.php with POST query, it mean it will have to load the file and create an object.

Problem:
Problem is when you access to ClassExample.php directly – it could not find class/pdoDatabase.php . It work fine when sales.php load class/pdoDatabase.php file

Answer 1

This is not a problem with include_once and include difference. This is a problem with relative paths. Include always uses paths relative to called php file. You have this file structure:

sales.php
[class]
 - pdoDatabase.php
 - ClassExample.php

when you call sales.php everything is ok, but when you call ClassExample.php it’s trying to find class/class/pdoDatabase.php which don’t exist.

Change include line in your ClassExample.php

include_once(dirname(__FILE__)."/pdoDatabase.php");

and use the same pattern everywhere.