def save_handler(sender, instance, *args, **kwargs):
model_label = sender._meta.label # noqa
channel_layer = get_channel_layer()
group_name = get_group_name(model_label)
async_to_sync(channel_layer.group_send)(
group_name,
{
"type": "model.saved",
"model": model_label,
"instance_pk": instance.pk,
"channel_name": group_name,
},
)
def receive_json(self, content: Dict[str, Any], **kwargs):
"""
Entrypoint for incoming messages from the connected client.
"""
request_id = content.get("id", None)
if request_id is None:
return # Can't send error message without request ID, so just return.
message_type = content.get("type", None)
if message_type == "subscribe":
model_label = content.get("model")
if model_label is None:
self.send_error(request_id, 400, "No model specified.")
return
if model_label not in self.registry:
self.send_error(
request_id,
404,
f"Model {model_label} not registered for realtime updates.",
)
return
view_action = content.get("action", None)
if view_action is None or view_action not in ["list", "retrieve"]:
self.send_error(
request_id,
400,
"`action` must be present and the value must be either `list` or `retrieve`.",
)
lookup_value = content.get("lookup_by", None)
view_kwargs = content.get("view_kwargs", dict())
query_params = content.get("query_params", dict())
view = self.registry[model_label].from_scope(
view_action, self.scope, view_kwargs, query_params)
model = view.get_model_class()
# Check to make sure client has permissions to make this subscription.
has_permission = True
for permission in view.get_permissions():
has_permission = has_permission and permission.has_permission(
view.request, view)
# Retrieve actions must check has_object_permission as well.
if view.action == "retrieve":
try:
instance = view.get_queryset().get(
**{view.lookup_field: lookup_value})
except model.DoesNotExist:
self.send_error(request_id, 404, "Instance not found.")
return
for permission in view.get_permissions():
has_permission = (has_permission
and permission.has_object_permission(
view.request, view, instance))
if not has_permission:
self.send_error(
request_id,
403,
f"Unauthorized to subscribe to {model_label} for action {view_action}",
)
return
# If we've reached this point, then the client can subscribe.
group_name = get_group_name(model_label)
print(f"[REST-LIVE] got subscription to {group_name}")
self.subscriptions.setdefault(group_name, []).append(request_id)
self.kwargs[request_id] = view_kwargs
self.params[request_id] = query_params
self.actions[request_id] = view_action
self.visible_instance_pks[request_id] = set([
instance1["pk"]
for instance1 in view.get_queryset().all().values("pk")
])
# Add subscribe to updates from channel layer: this is the "actual" subscription action.
async_to_sync(self.channel_layer.group_add)(group_name,
self.channel_name)
self.groups.append(group_name)
elif message_type == "unsubscribe":
# Get the group name given the request_id
try:
# List comprehension is empty if the provided request_id doesn't show up for this consumer
group_name = [
k for k, v in self.subscriptions.items() if request_id in v
][0]
except IndexError:
self.send_error(
request_id,
404,
"Attempted to unsubscribe for request ID before subscribing.",
)
return
del self.actions[request_id]
del self.kwargs[request_id]
del self.visible_instance_pks[request_id]
self.subscriptions[group_name].remove(request_id)
self.groups.remove(
group_name) # Removes the first occurance of this group name.
if (
group_name not in self.groups
): # If there are no more occurances, unsubscribe to the channel layer.
async_to_sync(self.channel_layer.group_discard)(
group_name, self.channel_name)
# Delete the key in the dictionary if no more subscriptions.
if len(self.subscriptions[group_name]) == 0:
del self.subscriptions[group_name]
else:
self.send_error(request_id, 400,
f"unknown message type `{message_type}`.")
def receive_json(self, content: Dict[str, Any], **kwargs):
"""
Entrypoint for incoming messages from the connected client.
"""
request_id = content.get("id", None)
if request_id is None:
return # Can't send error message without request ID, so just return.
message_type = content.get("type", None)
if message_type == "subscribe":
model_label = content.get("model")
if model_label is None:
self.send_error(request_id, 400, "No model specified.")
return
if model_label not in self.registry:
self.send_error(
request_id,
404,
f"Model {model_label} not registered for realtime updates.",
)
return
view_action = content.get("action", None)
if view_action is None or view_action not in ["list", "retrieve"]:
self.send_error(
request_id,
400,
"`action` must be present and the value must be either `list` or `retrieve`.",
)
lookup_value = content.get("lookup_by", None)
view_kwargs = content.get("view_kwargs", dict())
query_params = content.get("query_params", dict())
view = self.registry[model_label].from_scope(
view_action, self.scope, view_kwargs, query_params)
# Check to make sure client has permissions to make this subscription.
has_permission = True
for permission in view.get_permissions():
has_permission = has_permission and permission.has_permission(
view.request, view)
# Retrieve actions use get_object() to check object permissions as well.
if view.action == "retrieve":
view.kwargs.setdefault(view.lookup_field, lookup_value)
try:
view.get_object()
except Http404:
self.send_error(
request_id,
404,
"Instance not found. Make sure 'lookup_by' is set to a valid ID",
)
return
except (NotAuthenticated, PermissionDenied):
has_permission = False
if not has_permission:
self.send_error(
request_id,
403,
f"Unauthorized to subscribe to {model_label} for action {view_action}",
)
return
# If we've reached this point, then the client can subscribe.
group_name = get_group_name(model_label)
print(f"[REST-LIVE] got subscription to {group_name}")
self.subscriptions.setdefault(group_name, []).append(
Subscription(
request_id,
action=view_action,
view_kwargs=view_kwargs,
query_params=query_params,
pks_to_lookup_in_queryset=dict({
inst["pk"]: inst[view.lookup_field]
for inst in view.get_queryset().all().values(
"pk", view.lookup_field)
}),
))
# Add subscribe to updates from channel layer: this is the "actual" subscription action.
async_to_sync(self.channel_layer.group_add)(group_name,
self.channel_name)
self.groups.append(group_name)
elif message_type == "unsubscribe":
# Get the group name given the request_id
try:
# List comprehension is empty if the provided request_id doesn't show up for this consumer
group_name = [
k for k, v in self.subscriptions.items()
if request_id in [s.request_id for s in v]
][0]
except IndexError:
self.send_error(
request_id,
404,
"Attempted to unsubscribe for request ID before subscribing.",
)
return
self.subscriptions[group_name] = [
sub for sub in self.subscriptions[group_name]
if sub.request_id != request_id
]
self.groups.remove(
group_name) # Removes the first occurrence of this group name.
if (
group_name not in self.groups
): # If there are no more occurrences, unsubscribe to the channel layer.
async_to_sync(self.channel_layer.group_discard)(
group_name, self.channel_name)
# Delete the key in the dictionary if no more subscriptions.
if len(self.subscriptions[group_name]) == 0:
del self.subscriptions[group_name]
else:
self.send_error(request_id, 400,
f"unknown message type `{message_type}`.")