def process_exception(self, request, exception):
# Don't catch exceptions when in debug mode
if settings.DEBUG:
return
# Ignore Http404s (defer to Django's built-in 404 handling)
if isinstance(exception, Http404):
return
# Handle exceptions that occur from REST API requests
if is_api_request(request):
return rest_api_server_error(request)
# Determine the type of exception. If it's a common issue, return a custom error page with instructions.
custom_template = None
if isinstance(exception, ProgrammingError):
custom_template = 'exceptions/programming_error.html'
elif isinstance(exception, ImportError):
custom_template = 'exceptions/import_error.html'
elif isinstance(exception, PermissionError):
custom_template = 'exceptions/permission_error.html'
# Return a custom error message, or fall back to Django's default 500 error handling
if custom_template:
return server_error(request, template_name=custom_template)
def __call__(self, request):
response = self.get_response(request)
if is_api_request(request):
response['API-Version'] = settings.REST_FRAMEWORK_VERSION
return response
def __call__(self, request):
# Initialize an empty list to cache objects being saved.
_thread_locals.changed_objects = []
# Assign a random unique ID to the request. This will be used to associate multiple object changes made during
# the same request.
request.id = uuid.uuid4()
# Connect our receivers to the post_save and post_delete signals.
post_save.connect(handle_changed_object,
dispatch_uid='handle_changed_object')
pre_delete.connect(handle_deleted_object,
dispatch_uid='handle_deleted_object')
# Provide a hook for purging the change cache
purge_changelog.connect(purge_objectchange_cache)
# Process the request
response = self.get_response(request)
# If the change cache is empty, there's nothing more we need to do.
if not _thread_locals.changed_objects:
return response
# Disconnect our receivers from the post_save and post_delete signals.
post_save.disconnect(handle_changed_object,
dispatch_uid='handle_changed_object')
pre_delete.disconnect(handle_deleted_object,
dispatch_uid='handle_deleted_object')
# Create records for any cached objects that were changed.
redis_failed = False
for instance, action in _thread_locals.changed_objects:
# Refresh cached custom field values
if action in [
ObjectChangeActionChoices.ACTION_CREATE,
ObjectChangeActionChoices.ACTION_UPDATE
]:
if hasattr(instance, 'cache_custom_fields'):
instance.cache_custom_fields()
# Record an ObjectChange if applicable
if hasattr(instance, 'to_objectchange'):
objectchange = instance.to_objectchange(action)
objectchange.user = request.user
objectchange.request_id = request.id
objectchange.save()
# Enqueue webhooks
try:
enqueue_webhooks(instance, request.user, request.id, action)
except RedisError as e:
if not redis_failed and not is_api_request(request):
messages.error(
request,
"There was an error processing webhooks for this request. Check that the Redis service is "
"running and reachable. The full error details were: {}"
.format(e))
redis_failed = True
# Increment metric counters
if action == ObjectChangeActionChoices.ACTION_CREATE:
model_inserts.labels(instance._meta.model_name).inc()
elif action == ObjectChangeActionChoices.ACTION_UPDATE:
model_updates.labels(instance._meta.model_name).inc()
elif action == ObjectChangeActionChoices.ACTION_DELETE:
model_deletes.labels(instance._meta.model_name).inc()
# Housekeeping: 1% chance of clearing out expired ObjectChanges. This applies only to requests which result in
# one or more changes being logged.
if settings.CHANGELOG_RETENTION and random.randint(1, 100) == 1:
cutoff = timezone.now() - timedelta(
days=settings.CHANGELOG_RETENTION)
purged_count, _ = ObjectChange.objects.filter(
time__lt=cutoff).delete()
return response
