250 lines
8.0 KiB
Python
250 lines
8.0 KiB
Python
import hashlib
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import time
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from typing import Dict, List, Optional, Tuple
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from django.core.cache import cache as default_cache
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from django.core.exceptions import ImproperlyConfigured
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from django.http import HttpRequest
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class BaseThrottle:
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"""
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Rate throttling of requests.
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"""
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def allow_request(self, request: HttpRequest) -> bool:
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"""
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Return `True` if the request should be allowed, `False` otherwise.
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"""
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raise NotImplementedError(".allow_request() must be overridden")
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def get_ident(self, request: HttpRequest) -> Optional[str]:
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"""
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Identify the machine making the request by parsing HTTP_X_FORWARDED_FOR
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if present and number of proxies is > 0. If not use all of
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HTTP_X_FORWARDED_FOR if it is available, if not use REMOTE_ADDR.
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"""
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from ninja.conf import settings
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xff = request.META.get("HTTP_X_FORWARDED_FOR")
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remote_addr = request.META.get("REMOTE_ADDR")
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num_proxies = settings.NUM_PROXIES
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if num_proxies is not None:
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if num_proxies == 0 or xff is None:
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return remote_addr
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addrs: List[str] = xff.split(",")
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client_addr = addrs[-min(num_proxies, len(addrs))]
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return client_addr.strip()
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return "".join(xff.split()) if xff else remote_addr
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def wait(self) -> Optional[float]:
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"""
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Optionally, return a recommended number of seconds to wait before
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the next request.
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"""
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return None
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class SimpleRateThrottle(BaseThrottle):
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"""
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A simple cache implementation, that only requires `.get_cache_key()`
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to be overridden.
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The rate (requests / seconds) is set by a `rate` attribute on the Throttle
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class. The attribute is a string of the form 'number_of_requests/period'.
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Period should be one of: ('s', 'sec', 'm', 'min', 'h', 'hour', 'd', 'day')
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Previous request information used for throttling is stored in the cache.
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"""
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from ninja.conf import settings
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cache = default_cache
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timer = time.time
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cache_format = "throttle_%(scope)s_%(ident)s"
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scope: Optional[str] = None
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THROTTLE_RATES: Dict[str, Optional[str]] = settings.DEFAULT_THROTTLE_RATES
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_PERIODS = {
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"s": 1,
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"m": 60,
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"h": 60 * 60,
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"d": 60 * 60 * 24,
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"sec": 1,
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"min": 60,
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"hour": 60 * 60,
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"day": 60 * 60 * 24,
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}
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def __init__(self, rate: Optional[str] = None):
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self.rate: Optional[str]
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if rate:
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self.rate = rate
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else:
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self.rate = self.get_rate()
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self.num_requests, self.duration = self.parse_rate(self.rate)
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def get_cache_key(self, request: HttpRequest) -> Optional[str]:
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"""
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Should return a unique cache-key which can be used for throttling.
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Must be overridden.
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May return `None` if the request should not be throttled.
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"""
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raise NotImplementedError(".get_cache_key() must be overridden")
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def get_rate(self) -> Optional[str]:
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"""
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Determine the string representation of the allowed request rate.
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"""
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if not getattr(self, "scope", None):
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msg = f"You must set either `.scope` or `.rate` for '{self.__class__.__name__}' throttle"
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raise ImproperlyConfigured(msg)
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try:
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return self.THROTTLE_RATES[self.scope] # type: ignore
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except KeyError:
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msg = f"No default throttle rate set for '{self.scope}' scope"
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raise ImproperlyConfigured(msg) from None
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def parse_rate(self, rate: Optional[str]) -> Tuple[Optional[int], Optional[int]]:
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"""
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Given the request rate string, return a two tuple of:
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<allowed number of requests>, <period of time in seconds>
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"""
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if rate is None:
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return (None, None)
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try:
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count, rest = rate.split("/", 1)
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for unit in self._PERIODS:
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if rest.endswith(unit):
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multi = int(rest[: -len(unit)]) if rest[: -len(unit)] else 1
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period = self._PERIODS[unit]
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break
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else:
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multi, period = int(rest), 1
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return int(count), multi * period
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except (ValueError, IndexError):
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raise ValueError(f"Invalid rate format: {rate}") from None
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def allow_request(self, request: HttpRequest) -> bool:
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"""
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Implement the check to see if the request should be throttled.
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On success calls `throttle_success`.
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On failure calls `throttle_failure`.
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"""
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# if self.rate is None:
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# return True
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self.key = self.get_cache_key(request)
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if self.key is None:
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return True
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self.history = self.cache.get(self.key, [])
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self.now = self.timer() # type: ignore
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# Drop any requests from the history which have now passed the
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# throttle duration
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while self.history and self.history[-1] <= self.now - self.duration: # type: ignore
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self.history.pop()
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if len(self.history) >= self.num_requests: # type: ignore
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return self.throttle_failure()
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return self.throttle_success()
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def throttle_success(self) -> bool:
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"""
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Inserts the current request's timestamp along with the key
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into the cache.
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"""
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self.history.insert(0, self.now)
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self.cache.set(self.key, self.history, self.duration)
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return True
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def throttle_failure(self) -> bool:
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"""
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Called when a request to the API has failed due to throttling.
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"""
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return False
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def wait(self) -> Optional[float]:
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"""
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Returns the recommended next request time in seconds.
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"""
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if self.history:
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remaining_duration = self.duration - (self.now - self.history[-1])
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else:
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remaining_duration = self.duration
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available_requests = self.num_requests - len(self.history) + 1 # type: ignore
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if available_requests <= 0:
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return None
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return remaining_duration / float(available_requests) # type: ignore
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class AnonRateThrottle(SimpleRateThrottle):
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"""
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Limits the rate of API calls that may be made by a anonymous users.
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The IP address of the request will be used as the unique cache key.
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"""
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scope = "anon"
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def get_cache_key(self, request: HttpRequest) -> Optional[str]:
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if getattr(request, "auth", None) is not None:
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return None # Only throttle unauthenticated requests.
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return self.cache_format % {
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"scope": self.scope,
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"ident": self.get_ident(request),
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}
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class AuthRateThrottle(SimpleRateThrottle):
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"""
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Limits the rate of API calls that may be made by a given user.
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The string representation of request.auth object will be used as a unique cache key.
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If you use custom auth objects make sure to implement __str__ method.
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For anonymous requests, the IP address of the request will be used.
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"""
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scope = "auth"
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def get_cache_key(self, request: HttpRequest) -> str:
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if getattr(request, "auth", None) is not None:
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ident = hashlib.sha256(str(request.auth).encode()).hexdigest() # type: ignore
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# TODO: ^maybe auth should have an attribute that developer can overwrite
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else:
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ident = self.get_ident(request) # type: ignore
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return self.cache_format % {"scope": self.scope, "ident": ident}
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class UserRateThrottle(SimpleRateThrottle):
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"""
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Limits the rate of API calls that may be made by a given user.
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The user id will be used as a unique cache key if the user is
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authenticated. For anonymous requests, the IP address of the request will
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be used.
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"""
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scope = "user"
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def get_cache_key(self, request: HttpRequest) -> str:
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if request.user and request.user.is_authenticated:
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ident = request.user.pk
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else:
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ident = self.get_ident(request)
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return self.cache_format % {"scope": self.scope, "ident": ident}
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