97 lines
3.8 KiB
Python
97 lines
3.8 KiB
Python
import copy
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from threading import local
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from django.db.models.signals import pre_delete, post_save
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from django.dispatch import receiver
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from django.http.response import HttpResponseServerError
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from orchestra.utils.python import OrderedSet
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from .backends import ServiceBackend
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from .helpers import message_user
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from .models import BackendLog
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from .models import BackendOperation as Operation
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@receiver(post_save)
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def post_save_collector(sender, *args, **kwargs):
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if sender != BackendLog:
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OperationsMiddleware.collect(Operation.SAVE, **kwargs)
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@receiver(pre_delete)
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def pre_delete_collector(sender, *args, **kwargs):
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if sender != BackendLog:
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OperationsMiddleware.collect(Operation.DELETE, **kwargs)
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class OperationsMiddleware(object):
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"""
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Stores all the operations derived from save and delete signals and executes them
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at the end of the request/response cycle
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"""
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# Thread local is used because request object is not available on model signals
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thread_locals = local()
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@classmethod
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def get_pending_operations(cls):
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# Check if an error poped up before OperationsMiddleware.process_request()
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if hasattr(cls.thread_locals, 'request'):
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request = cls.thread_locals.request
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if not hasattr(request, 'pending_operations'):
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request.pending_operations = OrderedSet()
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return request.pending_operations
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return set()
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@classmethod
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def collect(cls, action, **kwargs):
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""" Collects all pending operations derived from model signals """
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request = getattr(cls.thread_locals, 'request', None)
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if request is None:
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return
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pending_operations = cls.get_pending_operations()
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for backend in ServiceBackend.get_backends():
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instance = None
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if backend.is_main(kwargs['instance']):
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instance = kwargs['instance']
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else:
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candidate = backend.get_related(kwargs['instance'])
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if candidate:
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delete = Operation.create(backend, candidate, Operation.DELETE)
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if delete not in pending_operations:
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instance = candidate
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# related objects with backend.model trigger save()
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action = Operation.SAVE
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if instance is not None:
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# Prevent creating a deleted instance by deleting existing saves
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if action == Operation.DELETE:
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save = Operation.create(backend, instance, Operation.SAVE)
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try:
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pending_operations.remove(save)
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except KeyError:
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pass
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else:
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update_fields = kwargs.get('update_fields', None)
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if update_fields:
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append = False
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for field in kwargs.get('update_fields', [None]):
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if field not in backend.ignore_fields:
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append = True
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break
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if not append:
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continue
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instance = copy.copy(instance)
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pending_operations.add(Operation.create(backend, instance, action))
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def process_request(self, request):
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""" Store request on a thread local variable """
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type(self).thread_locals.request = request
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def process_response(self, request, response):
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""" Processes pending backend operations """
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if not isinstance(response, HttpResponseServerError):
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operations = type(self).get_pending_operations()
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if operations:
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logs = Operation.execute(operations)
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if logs:
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message_user(request, logs)
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return response
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