How do you know the correct path to use in a PHP require_once() statement

Question

As many do I have a config.php file in the root of a web app that I want to include in almost every other php file. So most of them have a line like:

require_on         


        

Answer 1

I use the dirname(__FILE__) thing like bobwienholt most the time, but what it could pay to do is have a base entry point that loads all your other code that defines a constant refereing to the root of the project, ie

define("ROOT",dirname(__FILE__).'/' ); 

and then later all you need to know is where the path is relative to root, ie:

require(ROOT . "/lib/tool/error.php"); 

note,

you should REALLY avoid paths with "../" at the start of them, they are not relative to the file, but relative to where you ARE and this creates broken-ass code.

 cd foo
 php bar/baz.php 
 -> some error saying it cant find the file
 cd bar 
 php baz.php 
 -> suddenly working.

Important

If you use "../" notation, it takes complete ignorance of the PHP Include Path, And ONLY considers where the person whom is running it is.

Answer 2

Since require and require_once are very similar to include and include_once, all the documentation is posted under the "include" functions doc area on php.net From that page

Files for including are first looked for in each include_path entry relative to the current working directory, and then in the directory of current script. E.g. if your include_path is libraries, current working directory is /www/, you included include/a.php and there is include "b.php" in that file, b.php is first looked in /www/libraries/ and then in /www/include/. If filename begins with ./ or ../, it is looked only in the current working directory.

Further, you can find all the current include paths by doing a "php -i" from the command line. You can edit the include path in your php.ini file, and also via ini_set(). You can also run the php_info() function in your page to get a printout of your env vars if the CLI is inconvenient.

Answer 3

The current working directory for PHP is the directory in which the called script file is located. If your files looked like this:

/A
   foo.php
   tar.php
   B/
       bar.php

If you call foo.php (ex: http://example.com/foo.php), the working directory will be /A/. If you call bar.php (ex: http://example.com/B/bar.php), the working directory will be /A/B/.

There is where it gets tricky. Let us say that foo.php is such:

<?php
require_once( 'B/bar.php' );
?>

And bar.php is:

<?php
require_once( 'tar.php');
?>

If we call foo.php, then bar.php will successfully call tar.php because tar.php and foo.php are in the same directory which happens to be the working directory. If you instead call bar.php, it will fail.

Generally you will see either in all files:

require_once( realpath( dirname( __FILE__ ) ).'/../../path/to/file.php' );

or with the config file:

// config file
define( "APP_ROOT", realpath( dirname( __FILE__ ) ).'/' );

with the rest of the files using:

require_once( APP_ROOT.'../../path/to/file.php' );

Answer 4

The only place I've seen the path evaluated from is the file that you are currently editing. I've never had any problems with it, but if you are, you might want to provide more information (PHP version, OS, etc).

Answer 5

I include this code at the top of every page:

//get basic page variables
$self=$_SERVER['PHP_SELF']; 
$thispath=dirname($_SERVER['PHP_SELF']);
$sitebasepath=$_SERVER['DOCUMENT_ROOT'];

//include the global settings, variables and includes

include_once("$sitebasepath/globals/global.include.php");

Include and require both take either a relative path or the full rooted path. I prefer working with the full path and make all my references like the inlcude statement above. This allows me to enter a general variable $sitebasepath that handles account specific information that may change from machine to machine and then simply type the path from the webroot, ie. /globals/whatever_file.php

I also use the $self variable in forms that may call themselves to handle data input.

Hope that helps.

Answer 6

Take a look at the function getcwd. http://us2.php.net/getcwd