Symfony doc说：
During each request,Symfony2 will set a global template variable app
in both Twig and PHP template engines by default. The app variable is
a GlobalVariables instance which will give you access to some
application specific variables automatically:
app.security – The
security context.
app.user – The current user object.
app.request – The request object.
app.session – The session
object.
app.environment – The current environment (dev,prod,
etc).
app.debug – True if in debug mode. False otherwise.
例子：
在树枝上：{{app.request.method}}
在PHP中：echo $app-> getRequest() – > getMethod()
在树枝上：{{app.user.username}}
但对于会话对象：
在树枝上：{{app.session.varname}}
用PHP：//我不知道,你知道如何调用吗？
我试过了：$session = $app-> getSession(‘uid’);但当我尝试将其存储到数据库时,它告诉我：
Catchable Fatal Error: Object of class
SymfonyComponentHttpFoundationSession could not be converted to
string in C:wampwww…
在PHP模板方面缺乏资源,但在我的情况下,由于某些原因我无法切换.
换句话说,问题在于PHP模板的等价物：
{{app.session.varname}}？
