mirror of
https://github.com/encode/django-rest-framework.git
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268 lines
7.8 KiB
Python
268 lines
7.8 KiB
Python
"""
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The :mod:`permissions` module bundles a set of permission classes that are used
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for checking if a request passes a certain set of constraints. You can assign a permission
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class to your view by setting your View's :attr:`permissions` class attribute.
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"""
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from django.core.cache import cache
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from djangorestframework import status
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from djangorestframework.response import ErrorResponse
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import time
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__all__ = (
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'BasePermission',
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'FullAnonAccess',
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'IsAuthenticated',
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'IsAdminUser',
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'IsUserOrIsAnonReadOnly',
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'PerUserThrottling',
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'PerViewThrottling',
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'PerResourceThrottling'
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)
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SAFE_METHODS = ['GET', 'HEAD', 'OPTIONS']
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_403_FORBIDDEN_RESPONSE = ErrorResponse(
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status.HTTP_403_FORBIDDEN,
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{'detail': 'You do not have permission to access this resource. ' +
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'You may need to login or otherwise authenticate the request.'})
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_503_SERVICE_UNAVAILABLE = ErrorResponse(
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status.HTTP_503_SERVICE_UNAVAILABLE,
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{'detail': 'request was throttled'})
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class BasePermission(object):
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"""
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A base class from which all permission classes should inherit.
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"""
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def __init__(self, view):
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"""
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Permission classes are always passed the current view on creation.
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"""
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self.view = view
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def check_permission(self, auth):
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"""
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Should simply return, or raise an :exc:`response.ErrorResponse`.
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"""
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pass
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class FullAnonAccess(BasePermission):
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"""
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Allows full access.
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"""
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def check_permission(self, user):
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pass
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class IsAuthenticated(BasePermission):
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"""
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Allows access only to authenticated users.
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"""
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def check_permission(self, user):
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if not user.is_authenticated():
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raise _403_FORBIDDEN_RESPONSE
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class IsAdminUser(BasePermission):
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"""
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Allows access only to admin users.
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"""
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def check_permission(self, user):
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if not user.is_staff:
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raise _403_FORBIDDEN_RESPONSE
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class IsUserOrIsAnonReadOnly(BasePermission):
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"""
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The request is authenticated as a user, or is a read-only request.
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"""
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def check_permission(self, user):
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if (not user.is_authenticated() and
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self.view.method not in SAFE_METHODS):
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raise _403_FORBIDDEN_RESPONSE
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class DjangoModelPermissions(BasePermission):
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"""
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The request is authenticated using `django.contrib.auth` permissions.
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See: https://docs.djangoproject.com/en/dev/topics/auth/#permissions
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It ensures that the user is authenticated, and has the appropriate
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`add`/`change`/`delete` permissions on the model.
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This permission should only be used on views with a `ModelResource`.
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"""
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# Map methods into required permission codes.
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# Override this if you need to also provide 'read' permissions,
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# or if you want to provide custom permisson codes.
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perms_map = {
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'GET': [],
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'OPTIONS': [],
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'HEAD': [],
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'POST': ['%(app_label)s.add_%(model_name)s'],
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'PUT': ['%(app_label)s.change_%(model_name)s'],
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'PATCH': ['%(app_label)s.change_%(model_name)s'],
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'DELETE': ['%(app_label)s.delete_%(model_name)s'],
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}
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def get_required_permissions(self, method, model_cls):
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"""
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Given a model and an HTTP method, return the list of permission
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codes that the user is required to have.
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"""
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kwargs = {
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'app_label': model_cls._meta.app_label,
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'model_name': model_cls._meta.module_name
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}
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try:
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return [perm % kwargs for perm in self.perms_map[method]]
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except KeyError:
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ErrorResponse(status.HTTP_405_METHOD_NOT_ALLOWED)
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def check_permission(self, user):
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method = self.view.method
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model_cls = self.view.resource.model
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perms = self.get_required_permissions(method, model_cls)
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if not user.is_authenticated or not user.has_perms(perms):
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raise _403_FORBIDDEN_RESPONSE
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class BaseThrottle(BasePermission):
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"""
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Rate throttling of requests.
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The rate (requests / seconds) is set by a :attr:`throttle` attribute
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on the :class:`.View` class. The attribute is a string of the form 'number of
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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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attr_name = 'throttle'
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default = '0/sec'
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timer = time.time
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def get_cache_key(self):
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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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"""
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pass
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def check_permission(self, auth):
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"""
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Check the throttling.
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Return `None` or raise an :exc:`.ErrorResponse`.
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"""
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num, period = getattr(self.view, self.attr_name, self.default).split('/')
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self.num_requests = int(num)
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self.duration = {'s': 1, 'm': 60, 'h': 3600, 'd': 86400}[period[0]]
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self.auth = auth
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self.check_throttle()
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def check_throttle(self):
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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 :meth:`throttle_success`.
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On failure calls :meth:`throttle_failure`.
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"""
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self.key = self.get_cache_key()
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self.history = cache.get(self.key, [])
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self.now = self.timer()
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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:
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self.history.pop()
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if len(self.history) >= self.num_requests:
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self.throttle_failure()
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else:
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self.throttle_success()
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def throttle_success(self):
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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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cache.set(self.key, self.history, self.duration)
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header = 'status=SUCCESS; next=%s sec' % self.next()
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self.view.add_header('X-Throttle', header)
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def throttle_failure(self):
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"""
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Called when a request to the API has failed due to throttling.
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Raises a '503 service unavailable' response.
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"""
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header = 'status=FAILURE; next=%s sec' % self.next()
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self.view.add_header('X-Throttle', header)
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raise _503_SERVICE_UNAVAILABLE
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def next(self):
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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
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return '%.2f' % (remaining_duration / float(available_requests))
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class PerUserThrottling(BaseThrottle):
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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 identifier if the user is
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authenticated. For anonymous requests, the IP address of the client will
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be used.
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"""
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def get_cache_key(self):
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if self.auth.is_authenticated():
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ident = self.auth.id
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else:
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ident = self.view.request.META.get('REMOTE_ADDR', None)
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return 'throttle_user_%s' % ident
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class PerViewThrottling(BaseThrottle):
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"""
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Limits the rate of API calls that may be used on a given view.
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The class name of the view is used as a unique identifier to
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throttle against.
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"""
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def get_cache_key(self):
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return 'throttle_view_%s' % self.view.__class__.__name__
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class PerResourceThrottling(BaseThrottle):
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"""
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Limits the rate of API calls that may be used against all views on
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a given resource.
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The class name of the resource is used as a unique identifier to
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throttle against.
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"""
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def get_cache_key(self):
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return 'throttle_resource_%s' % self.view.resource.__class__.__name__
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