关于 tornado 的两个问题

[tywtyw2002]

一、tornado 如何才能stop整个请求链然后去抛出错误呢？
比如说，进入了ManageHandler的get，
get在查询数据库，数据库错误了，raise了一个database的error，
接下来error handler把这个错误给接管了，抛出一个错误页面，然后结束这个请求链。
用finish()去结束的话报错。。。。。


二、也是关于请求链终止的问题。
比如说，进入了ManageHandler的get，
但是ManageHandler要在 init的时候判断下用户的权限，如果用户的权限不够，直接抛出404页面。
class ManageHandler(BaseHandler):

def __init__(self, *argc, **argkw):
super(ManageHandler, self).__init__(*argc, **argkw)
self.private_auth()


def private_auth(self):
self.user = self.get_secure_cookie("user")
self.private = self.UserModel.get_user_level_by_name(self.user)

#not login
if self.private == -1:
return

if self.private != 4:
self.render("404.html")
self.finish()
然后这样用finish也报错
[E 140321 02:06:04 iostream:357] Uncaught exception, closing connection.
Traceback (most recent call last):
File "/Library/Python/2.7/site-packages/tornado/iostream.py", line 354, in wrapper
callback(*args)
File "/Library/Python/2.7/site-packages/tornado/stack_context.py", line 331, in wrapped
raise_exc_info(exc)
File "/Library/Python/2.7/site-packages/tornado/stack_context.py", line 302, in wrapped
ret = fn(*args, **kwargs)
File "/Library/Python/2.7/site-packages/tornado/httpserver.py", line 328, in _on_headers
self.request_callback(self._request)
File "/Library/Python/2.7/site-packages/tornado/web.py", line 1651, in __call__
handler = spec.handler_class(self, request, **spec.kwargs)
File "/Users/tyw/Workspaces/CMPUT391/trunk/app/handlers/ManageHandler.py", line 23, in __init__
self.private_auth()
File "/Users/tyw/Workspaces/CMPUT391/trunk/app/handlers/ManageHandler.py", line 36, in private_auth
self.finish()
File "/Library/Python/2.7/site-packages/tornado/web.py", line 837, in finish
self.flush(include_footers=True)
File "/Library/Python/2.7/site-packages/tornado/web.py", line 784, in flush
for transform in self._transforms:
TypeError: 'NoneType' object is not iterable
[E 140321 02:06:04 ioloop:491] Exception in callback <functools.partial object at 0x10c63e1b0>
Traceback (most recent call last):
File "/Library/Python/2.7/site-packages/tornado/ioloop.py", line 477, in _run_callback
callback()
File "/Library/Python/2.7/site-packages/tornado/stack_context.py", line 331, in wrapped
raise_exc_info(exc)
File "/Library/Python/2.7/site-packages/tornado/stack_context.py", line 302, in wrapped
ret = fn(*args, **kwargs)
File "/Library/Python/2.7/site-packages/tornado/iostream.py", line 354, in wrapper
callback(*args)
File "/Library/Python/2.7/site-packages/tornado/stack_context.py", line 331, in wrapped
raise_exc_info(exc)
File "/Library/Python/2.7/site-packages/tornado/stack_context.py", line 302, in wrapped
ret = fn(*args, **kwargs)
File "/Library/Python/2.7/site-packages/tornado/httpserver.py", line 328, in _on_headers
self.request_callback(self._request)
File "/Library/Python/2.7/site-packages/tornado/web.py", line 1651, in __call__
handler = spec.handler_class(self, request, **spec.kwargs)
File "/Users/tyw/Workspaces/CMPUT391/trunk/app/handlers/ManageHandler.py", line 23, in __init__
self.private_auth()
File "/Users/tyw/Workspaces/CMPUT391/trunk/app/handlers/ManageHandler.py", line 36, in private_auth
self.finish()
File "/Library/Python/2.7/site-packages/tornado/web.py", line 837, in finish
self.flush(include_footers=True)
File "/Library/Python/2.7/site-packages/tornado/web.py", line 784, in flush
for transform in self._transforms:
TypeError: 'NoneType' object is not iterable

[binux]

我觉得是你用法有误

一、抛异常本来就不会继续执行啊
二、在get里面调self.private_auth()，如果不成功 return 掉就好了

[tywtyw2002]

@binux 我在init里面掉是因为 有6个 get/post都用这个 private_auth()， 那些class 都继承在这个class的下面，我想这样可能方便一些。

[binux]

@tywtyw2002
那应该用
http://www.tornadoweb.org/en/stable/overview.html#id1

[tywtyw2002]

@binux User authentication 不是只判断用户是否登录了吗，没登陆的话跳到login页面。

我看了tornado自带的，没有发现他能跳到一个错误页面呀。

[binux]

@tywtyw2002
1、 login url 是可以设置的（不建议）
2、 在 get_current_user 里面 raise HTTPError(404)
3、 再写一个修饰器

[ushuz]

async才需要自己调finish
raise tornado.web.HTTPError(404)来抛出异常，看文档里面有怎么自定义错误页面

[walleL]

http://www.tornadoweb.org/en/stable/web.html#tornado.web.RequestHandler.prepare
楼主试试这个

[zeayes]

@ushuz 是这样的，async需要自己finish，否则tornado自动finish。

问题1：楼主可以用异步请求，catch住异常，再处理。

问题2：可以用装饰器处理。

[tywtyw2002]

@walleL thanks