How to stop execution after self.redirect

问题

How to stop execution after self.redirect in request initilization?

The method redirect does not stop/halt script execution. My initilizer method is called but the process continues into method AnswerHandler.get() but self.user is None because user is not logged.

class BaseRequestHandler(webapp.RequestHandler):
    def __init__(self):
        self.user = None

    def initialize(self, request=None, response=None):
        super(BaseRequestHandler,self).initialize(request, response)

        user = users.get_current_user()

        if not user:
            return self.redirect(users.create_login_url(request.uri))

        self.user = user

class AnswerHandler(BaseRequestHandler):

    def get(self):
        answer = Answer.next_answer_by_user(self.user)
        self.write_template({"answer" : answer})

Tanks!

回答1:

I would go with this solution:

class BaseRequestHandler(webapp.RequestHandler):
    def __init__(self):
        self.user = None

    def setAuthUser(self):
        user = users.get_current_user()
        if not user:
            self.redirect(users.create_login_url(request.uri))
            return False
        self.user = user
        return True

class AnswerHandler(BaseRequestHandler):
    def get(self):
        if not self.setAuthUser():
            return
        answer = Answer.next_answer_by_user(self.user)
        self.write_template({"answer" : answer})

I understand that you would like to work around having to have 2 lines of code in every handler.

If you really want that, your other option would be:

class BaseRequestHandler(webapp.RequestHandler):
    def __init__(self):
        self.user = None

    def get(self):
        self.user = users.get_current_user()
        if not self.user:
          self.redirect(users.create_login_url(request.uri))
          return
        self.doGet()

    def doGet(self):
        raise Exception("doGet() needs to be implemented by a subclass.")

class AnswerHandler(BaseRequestHandler):
    def doGet(self):
        answer = Answer.next_answer_by_user(self.user)
        self.write_template({"answer" : answer})

回答2:

With webapp2, there is an optional abort parameter:

redirect(uri, permanent=False, abort=False, code=None, body=None)

Taken from the api here

回答3:

I accomplished this by using the abort() method and using a custom exception handler, thus trapping the exception

来源：https://stackoverflow.com/questions/9231880/how-to-stop-execution-after-self-redirect