Symfony/Silex + Facebook SDK:会话开始冲突

Question

如何在不更改原始源代码的情况下解决session_start冲突？Symfony组件或Silex如何检查会话是否已存在？

Notice: A session had already been started - ignoring session_start() in
myapp/vendor/symfony/http-foundation/Symfony/Component/HttpFoundation/Session/Storage/NativeSessionStorage.php on line 146

编辑:这是index.php的前几行

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

/**
 * from Heroku's Facebook template
 */
require_once('AppInfo.php');
require_once('utils.php');


use Symfony\Component\HttpFoundation\Request;
use Symfony\Component\HttpFoundation\Response;
use Symfony\Component\HttpKernel\HttpKernelInterface;
use Symfony\Component\Yaml\Parser;
use Silex\Provider\FormServiceProvider;
use Symfony\Component\Validator\Constraints as Assert;

/**
 * Currently using git submodule, will move to composer.json
 */
require_once('sdk/src/facebook.php');

$facebook = new Facebook(array(
  'appId'  => AppInfo::appID(),
  'secret' => AppInfo::appSecret(),
));

$app = new Silex\Application();
// ...

Answer 1

FB sdk 只有在尚未启动时才会启动会话.在启动silex会话的代码之后移动sdk初始化.

这是Symfony2用于查看用户是否有会话的功能.实质上,它检查会话cookie的存在.