Fatal error: Class not found in codeigniter - php

Question

I have created a model Admin_Model under Application\core directory of code igniter. I put all basic database operations under it. When I try to extend my models who are under Application\model directory, it throws error.
Fatal error: Class 'Admin_Model' not found in <path to root>/application/models/new_model.php on line 3
Should I miss any configuration?

Answer 1

Thanks all for your efforts.
I find a solution.
By default CodeIgniter have a setting in its config file.
$config['subclass_prefix'] = 'MY_';
I just replace 'MY_' with 'Admin_' everything works fine.
$config['subclass_prefix'] = 'Admin_';
More appropriate solution is
Put class file in libraries folder
Add following code to config.php
function __autoload($classname)
{
if(strpos($classname,'CI_') == 0)
{
$file = APPPATH.'libraries/'.$classname.'.php';
if(file_exists($file))
{
#include_once($file);
}
}
}
That's All

Answer 2

This may also be helpful, if you still have problems with __autoload to use class from libraries. it's work for me, when I use class library tobe parent class at controller.
PHP 5 >= 5.1.2, PHP 7
this is mycode at application/config.php
spl_autoload_register(function ($classname){
if(strpos($classname,'CI_') == 0){
$file = APPPATH.'libraries/'.$classname.'.php';
if(file_exists($file)){
#include_once($file);
}
}
});

Answer 3

Extending Core Class
If all you need to do is add some functionality to an existing library - perhaps add a function or two - then it's overkill to replace the entire library with your version. In this case it's better to simply extend the class. Extending a class is nearly identical to replacing a class with a couple exceptions:
The class declaration must extend the parent class.
Your new class name and filename must be prefixed with MY_ (this item is configurable. See below.).
For example, to extend the native Model class you'll create a file named application/core/MY_Model.php, and declare your class with:
class MY_Model extends CI_Model {
}
Note: If you need to use a constructor in your class make sure you extend the parent constructor:
class MY_Model extends CI_Model {
function __construct()
{
parent::__construct();
}
}

Answer 4

I setup my environment on a Windows machine. Then after move to production using Ubuntu, I had the class not found error.
I discovered my files extension were PHP (capital letter). Linux is case sensitive, so the file name need to be lowercase php.