Create Simple Codeigniter library - php

Question

For my current project i decided to create a library for some common functionalities.
Ex : Login_check,get_current_user etc.
With my little knowledge i created a simple one but unfortunately its not working.
Here my library :
FileName : Pro.php and located in application/libraries
class Pro{
public function __construct()
{
parent::_construct();
$CI =& get_instance();
$CI->load->helper('url');
$CI->load->library('session');
$CI->load->database();
}
function show_hello_world()
{
$text = "Hello World";
return $text;
}
}
?>
And i tried to load it on my controller :
<?php
class Admin extends CI_Controller
{
function __construct()
{
parent::__construct();
$this->load->database();
$this->load->library(array('session'));
$this->load->library("Pro");
}
function index()
{
echo($this->Pro->show_hello_world());
}
}
?>
I cant see any erros there...but i am getting a blank page.
Whats wrong with me ??
Thank you .
Edit : I got this error :
Call to a member function show_hello_world() on a non-object in C:\wamp\www\Project\application\controllers\admin.php on line 13

Answer 1

One thing I notice: remove the parent::__construct() from your library constructor, because it's not extending anything so has no parent to call.
Also, enable error reporting by setting the environment to "development" in index.php, and you might also want to raise the logging threshold to 4 in config/config.php so you log errors.
Try this simple test-case:
file Pro.php in application/libraries:
class Pro {
function show_hello_world()
{
return 'Hello World';
}
}
Controller admin.php in application/controllers
class Admin extends CI_Controller
{
function index()
{
$this->load->library('pro');
echo $this->pro->show_hello_world();
}
}

Answer 2

while your class name is capitalized, all your references to the library when loading it and using it should be lower case. you also do not need the constructor, as the other commenter mentioned.
so instead of:
echo($this->Pro->show_hello_world());
you should have:
echo($this->pro->show_hello_world());

Answer 3

I prefer the standard php autoloader approach, with this you dont need to change your classes at all, you can use your standard classes without modifications
say for instance you class is class 'Custom_Example_Example2' and is stored in libraries
in sub folders you can add this autoloader in the master index.php
make sure it is added below the defined APPPATH constant
//autoload custom classes
function __autoload($className) {
if (strlen(strstr($className, 'Custom_')) > 0 ||
strlen(strstr($className, 'Other1_')) > 0 ||
strlen(strstr($className, 'Other2_')) > 0) {
$exp = explode('_', $className);
$file = APPPATH.'libraries';
if(!empty($exp)) {
foreach($exp as $segment) {
$file .= '/'.strtolower($segment);
}
}
$file .= '.php';
require_once $file;
//debug
//echo $file.'<br />';
}
}
This will look for class calls matching the 'Custom_' prefix
and reroute them to the relative location in this case
you only need to define the base prefix not the sub folders / classes
these will be auto detected by this code
APPPATH.'libraries/custom/example/example2.php'
You can call it in the controller the standard php way
$class = new Custom_Example_Example2;
or
$class = new custom_example_example2();
You can modify the script to your liking currently it expects all folders and filenames in the library to be lowercase but you can remove the strtolower() function to allow multiple casing.
you can change the require once to echo to test the output by uncommenting this line and refresh the page, make sure you have a class init / test in the controller or model to run the test
echo $file.'<br />';
Thanks
Daniel

Answer 4

In Pro.php
class Pro{
protected $CI;
public function __construct() {
$this->CI = & get_instance();
}
public function showHelloWorld(){
return "Hello World";
}
}
In your controller
class Staff extends CI_Controller {
public function __construct() {
parent::__construct();
$this->load->database();
$this->load->helper(array('url_helper', 'url'));
$this->load->library("pro");
}
public function index() {
echo $this->pro->showHelloWorld();die;
}
}
Just do these things you can access your custom library in codeignitor.