How to use the py4web.core.Fixture function in py4web

class Fixture:
    def on_request(self):
        pass  # called when a request arrives

    def on_error(self):
        pass  # called when a request errors

    def on_success(self):
        pass  # called when a request is successful

    def transform(self, output):  # transforms the output, for example to apply template
        return output


class Translator(pluralize.Translator, Fixture):
    def on_request(self):
        self.select(request.headers.get("Accept-Language", "en"))

    def on_success(self):
        response.headers["Content-Language"] = self.local.tag


class DAL(pydal.DAL, Fixture):
    def on_request(self):
        threadsafevariable.ThreadSafeVariable.restore(ICECUBE)

    def on_error(self):
        self.rollback()

    def on_success(self):
        self.commit()

def on_success(self):
        pass  # called when a request is successful

    def transform(self, output):  # transforms the output, for example to apply template
        return output


class Translator(pluralize.Translator, Fixture):
    def on_request(self):
        self.select(request.headers.get("Accept-Language", "en"))

    def on_success(self):
        response.headers["Content-Language"] = self.local.tag


class DAL(pydal.DAL, Fixture):
    def on_request(self):
        threadsafevariable.ThreadSafeVariable.restore(ICECUBE)

    def on_error(self):
        self.rollback()

    def on_success(self):
        self.commit()


# make sure some variables in pydal are thread safe
for _ in ["readable", "writable", "default", "update", "requires"]:
    setattr(pydal.DAL.Field, _, threadsafevariable.ThreadSafeVariable())

# this global object will be used to store their state to restore it for every http request
ICECUBE = {}

self.commit()


# make sure some variables in pydal are thread safe
for _ in ["readable", "writable", "default", "update", "requires"]:
    setattr(pydal.DAL.Field, _, threadsafevariable.ThreadSafeVariable())

# this global object will be used to store their state to restore it for every http request
ICECUBE = {}

#########################################################################################
# The Template Rendered Fixture
#########################################################################################


class Template(Fixture):

    cache = Cache(100)

    def __init__(self, filename, path=None, delimiters="[[ ]]"):
        self.filename = filename
        self.path = path
        self.delimiters = delimiters

    @staticmethod
    def reader(filename):
        """Cached file reader, only reads template if it has changed"""

        def raw_read():
            with open(filename, encoding="utf8") as stream:
                return stream.read()

import datetime
import hashlib
import urllib
import uuid

from py4web import redirect, request, response, abort, URL, action
from py4web.core import Fixture, Template
from pydal.validators import IS_EMAIL, CRYPT, IS_NOT_EMPTY, IS_NOT_IN_DB


class AuthEnforcer(Fixture):

    """
    Base fixtures that checks if a condition is met
    if not redirects to a different pages or returns HTTP 403
    """

    def __init__(self, auth, condition=None):
        self.__prerequisites__ = [auth]
        self.auth = auth
        self.condition = condition

    def abort_or_rediect(self, page):
        """
        return HTTP 403 if content_type is applicaitons/json
        else redirects to page"""
        if request.content_type == "application/json":

output = yatl.render(
            Template.reader(filename),
            path=path,
            context=context,
            delimiters=self.delimiters,
            reader=Template.reader,
        )
        return output


#########################################################################################
# The Session Fixture
#########################################################################################


class Session(Fixture):

    # All apps share the same default secret if not specified. important for _dashboard reload
    SECRET = None

    def __init__(
        self,
        secret=None,
        expiration=None,
        algorithm="HS256",
        storage=None,
        same_site="Lax",
    ):
        """
        secret is the shared key used to encrypt the session (using algorithm)
        expiration is in seconds
        (optional) storage must have a get(key) and set(key,value,expiration) methods

from py4web.core import Reloader, dumps, ErrorStorage, Session, Fixture
from pydal.validators import CRYPT
from yatl.helpers import BEAUTIFY
from .utils import *

MODE = os.environ.get("PY4WEB_DASHBOARD_MODE", "none")
FOLDER = os.environ["PY4WEB_APPS_FOLDER"]
APP_FOLDER = os.path.dirname(__file__)
T_FOLDER = os.path.join(APP_FOLDER, "translations")
T = Translator(T_FOLDER)
error_storage = ErrorStorage()
db = error_storage.db
session = Session()


class Logged(Fixture):
    def __init__(self, session):
        self.__prerequisites__ = [session]
        self.session = session

    def on_request(self):
        user = self.session.get("user")
        if not user or not user.get("id"):
            abort(403)


session_secured = action.uses(Logged(session))

if MODE in ("demo", "readonly", "full"):

    @action("index")
    @action.uses("index.html", session, T)

else redirects to page"""
        if request.content_type == "application/json":
            abort(403)
        redirect(URL(self.auth.route, page))

    def on_request(self):
        """check that we have a user in the session and
        the condition is met"""
        user = self.auth.session.get("user")
        if not user or not user.get("id"):
            self.abort_or_rediect("login")
        if callable(self.condition) and not self.condition(user):
            self.abort_or_rediect("not-authorized")


class Auth(Fixture):

    messages = {
        "verify_email": {
            "subject": "Confirm email",
            "body": "Welcome {first_name}, click {link} to confirm your email",
        },
        "reset_password": {
            "subject": "Password reset",
            "body": "Hello {first_name}, click {link} to change password",
        },
        "unsubscribe": {
            "subject": "Unsubscribe confirmation",
            "body": "By {first_name}, you have been erased from our system",
        },
    }