Why my autoload.php of composer doesn't work?

问题

I have a project, I use Composer and i import many thing by it... i require the autoload.php in my index (the root of project) and istead Slim, Mongo, Twig work very well. But when I call a class of Respect/Validation it doens't work; if I simply use Respect/Validation the error is:

Class 'Respect\Validation\Validator' not found in (path of file when i need it).

if I try to require also here the autoload.php the errors are:

**Warning**: require_once(vendor/autoload.php): failed to open stream: No such file or directory in (path of file when i need it)

**Fatal error**: require_once(): Failed opening required 'vendor/autoload.php' (include_path='.;C:\xampp\php\PEAR') in (path of file when i need it)

回答1:

If you are using a file (file.php) in a particular directory like this:

/app/controller/validation

and your vendor directory is in the base path of the project, you need to include the relative path to vendor directory:

../../../vendor/autoload.php

回答2:

Try using php composer dump-autoload. It may fix that problem.

回答3:

I did this. i checked the file and permissions as always but everything looks ok. Then I open autoload.php and see ... oh! we have __DIR__ ofcourse.

I was doing this

require '../../vendor.autoload.php';

Changed to

require __DIR__.'../../vendor.autoload.php';

Not politically correct but got me by the frustrating waste of time for the moment.

ofcourse there are better alternatives to __DIR__ like using a BASE Path etc. But this worked for me.

回答4:

I had the same issue with xampp. I installed composer and used:

composer create-project --stability=dev --prefer-dist yiisoft/yii2-app-basic D:\xampp\htdocs\newapp

My issue solved now.

回答5:

I had the same problem and i solved it by using the last version of laravel, just try this code to create your project:

composer create-project laravel/laravel exampleProject --prefer-dist

this always uses the last version.

回答6:

I solved simple re-run composer update from the project Root. (my case was on Magento2, but the error and the path are the same)

回答7:

In my case i simple forgot to change my working directory before running the command composer require cboden/ratchet in cmd this fixed it cd c:\path to project\ then composer require cboden/ratchet

回答8:

I solve the problem without any install or update of composer and just by moving require_once from sub class to main page.

require_once 'vendor/autoload.php';

来源：https://stackoverflow.com/questions/18312707/why-my-autoload-php-of-composer-doesnt-work