basehandler.py

# *-* coding: UTF-8 *-*

# shortened version of https://raw.github.com/coto/gae-boilerplate/master/boilerplate/lib/basehandler.py

# standard library imports
import logging
# related third party imports
import webapp2
from webapp2_extras import jinja2
from webapp2_extras import sessions
# local application/library specific imports
import models
from google.appengine.api import users
import socket
from urlparse import urlparse


def jinja2_factory(app):
    j = jinja2.Jinja2(app)
    j.environment.filters.update({
        # Set filters.
        # ...
    })
    j.environment.globals.update({
        # Set global variables.
        'uri_for': webapp2.uri_for,
        'getattr': getattr,
        'session': BaseHandler.session,
    })
    j.environment.tests.update({
        # Set test.
        # ...
    })
    return j


class ViewClass:
    """
        ViewClass to insert variables into the template.

        ViewClass is used in BaseHandler to promote variables automatically that can be used
        in jinja2 templates.
        Use case in a BaseHandler Class:
            self.view.var1 = "hello"
            self.view.array = [1, 2, 3]
            self.view.dict = dict(a="abc", b="bcd")
        Can be accessed in the template by just using the variables liek {{var1}} or {{dict.b}}
    """
    pass


class BaseHandler(webapp2.RequestHandler):
    """
        BaseHandler for all requests

        Holds the auth and session properties so they
        are reachable for all requests
    """

    def __init__(self, request, response):
        """ Override the initialiser in order to set the language.
        """
        self.initialize(request, response)
        self.view = ViewClass()

    def dispatch(self):
        """
            Get a session store for this request.
        """
        self.session_store = sessions.get_store(request=self.request)

        try:
            # Dispatch the request.
            webapp2.RequestHandler.dispatch(self)
        finally:
            # Save all sessions.
            self.session_store.save_sessions(self.response)

    @webapp2.cached_property
    def session_store(self):
        return sessions.get_store(request=self.request)

    @webapp2.cached_property
    def session(self):
        # Returns a session using the default cookie key.
        return self.session_store.get_session()

    @webapp2.cached_property
    def auth_config(self):
        """ Dict to hold urls for login/logout """
        return {
            #'login_url': users.create_login_url(self.request.url),
            'login_url': users.create_login_url('/login-return'),
            'logout_url': users.create_logout_url('/')
        }

    @webapp2.cached_property
    def user(self):
        return users.get_current_user()

    @webapp2.cached_property
    def user_id(self):
        return str(self.user.user_id()) if self.user else None

    @webapp2.cached_property
    def email(self):
        return self.user.email() if self.user else None

    @webapp2.cached_property
    def nickname(self):
        return self.user.nickname() if self.user else None

    @webapp2.cached_property
    def is_user_admin(self):
        return users.is_current_user_admin()

    @webapp2.cached_property
    def messages(self):
        return self.session.get_flashes(key='_messages')

    def add_message(self, message, level=None):
        self.session.add_flash(message, level, key='_messages')

    @webapp2.cached_property
    def jinja2(self):
        return jinja2.get_jinja2(factory=jinja2_factory, app=self.app)

    def render_template(self, filename, **kwargs):

        referer = self.request.referer
        referer_domain = None
        if referer != None:
            parsed_uri = urlparse(referer)
            referer_domain = '{uri.scheme}://{uri.netloc}/'.format(uri=parsed_uri)

        # make all self.view variables available in jinja2 templates
        if hasattr(self, 'view'):
            kwargs.update(self.view.__dict__)

        # set or overwrite special vars for jinja templates
        kwargs.update({
            'user': self.user,
            'user_id': self.user_id,
            'email': self.email,
            'nickname': self.nickname,
            'is_user_admin': self.is_user_admin,
            'url': self.request.url,
            'path': self.request.path,
            'query_string': self.request.query_string,
            'session': self.session,
            'referer': referer,# None or refereing URL
            'referer_domain': referer_domain,
            'server': socket.getfqdn(),
        })
        kwargs.update(self.auth_config)
        if self.messages:
            kwargs['messages'] = self.messages

        self.response.headers.add_header('X-UA-Compatible', 'IE=Edge,chrome=1')
        self.response.write(self.jinja2.render_template(filename, **kwargs))