php - file_get_contents with relative path

Question

I have the following directory structure.

/var/www/base/controller/detail.php
/var/www/base/validate/edit.json
/var/www/html

Within /var/www/base/controller/detail.php, how do I use file_get_contents() with a relative path to read /var/www/base/validate/edit.json? I've tried the following:

//failed to open stream: No such file or directory (error no: 2)
$json=file_get_contents('detail.php');

//No error, but I don't want this file and was just testing
$json=file_get_contents('detail.php', FILE_USE_INCLUDE_PATH);

//failed to open stream: No such file or directory (error no: 2)
$json=file_get_contents('./validate/edit.json', FILE_USE_INCLUDE_PATH);
//failed to open stream: No such file or directory (error no: 2)
$json=file_get_contents('../validate/edit.json', FILE_USE_INCLUDE_PATH);
//failed to open stream: No such file or directory (error no: 2)
$json=file_get_contents('././validate/edit.json', FILE_USE_INCLUDE_PATH);
//failed to open stream: No such file or directory (error no: 2)
$json=file_get_contents('../../validate/edit.json', FILE_USE_INCLUDE_PATH);

//This works, but I want to use a relative path
$json=file_get_contents(dirname(dirname(__FILE__)).'/validate/edit.json');

Answer 1

Have you tried:

$json = file_get_contents(__DIR__ . '/../validate/edit.json');

__DIR__ is a useful magic constant.

For reasons why, see http://yagudaev.com/posts/resolving-php-relative-path-problem/.

When a PHP file includes another PHP file which itself includes yet another file — all being in separate directories — using relative paths to include them may raise a problem.

PHP will often report that it is unable to find the third file, but why? Well the answer lies in the fact that when including files in PHP the interpreter tries to find the file in the current working directory.

In other words, if you run the script in a directory called A and you include a script that is found in directory B, then the relative path will be resolved relative to A when executing a script found in directory B.

So, if the script inside directory B includes another file that is in a different directory, the path will still be calculated relative to A not relative to B as you might expect.