mirror of
https://github.com/jazzband/django-ddp.git
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62 lines
1.8 KiB
Python
62 lines
1.8 KiB
Python
"""Django DDP notification support."""
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from __future__ import absolute_import
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import collections
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import ejson
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from django.db import connections
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from django.utils.module_loading import import_string
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from dddp.api import collection_name
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from dddp.models import Subscription
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from dddp.msg import obj_change_as_msg
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class ImportCache(collections.defaultdict):
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@staticmethod
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def __missing__(key):
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return import_string(key)
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_CLS_CACHE = ImportCache()
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def send_notify(model, obj, msg, using):
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"""Dispatch PostgreSQL async NOTIFY."""
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col_name = collection_name(model)
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if col_name == 'migrations.migration':
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return # never send migration models.
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if col_name.startswith('dddp.'):
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return # don't send DDP internal models.
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sub_ids = set()
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for sub in Subscription.objects.filter(
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collections__name=col_name,
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):
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pub = _CLS_CACHE[sub.publication_class]()
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pub_queries = {
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collection_name(qs.model): qs
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for qs
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in pub.get_queries(*sub.params)
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if qs.model is model
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}
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for sub_col in sub.collections.filter(
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name=col_name,
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):
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qs = pub_queries[sub_col.name]
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col = _CLS_CACHE[sub_col.collection_class]()
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# filter qs using user_rel paths on collection
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qs = col.get_queryset(qs)
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if qs.filter(pk=obj.pk).exists():
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sub_ids.add(sub.sub_id)
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if not sub_ids:
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return # no subscribers for this object, nothing more to do.
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name, payload = obj_change_as_msg(obj, msg)
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payload['_sub_ids'] = sorted(sub_ids)
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cursor = connections[using].cursor()
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cursor.execute(
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'NOTIFY "%s", %%s' % name,
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[
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ejson.dumps(payload),
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],
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)
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