T50470: push websocket updates upon saving models

Author: knokko

README.md

@@ -15,7 +15,7 @@ Run with docker `docker compose run binder ./setup.py test` (but you may need to
 
 The tests are set up in such a way that there is no need to keep migration files. The setup procedure in `tests/__init__.py` handles the preparation of the database by directly calling some build-in Django commands.
 
-To only run a selection of the tests, use the `-s` flag like `./setup.py test -s tests.test_some_specific_test`.
+To only run a selection of the tests, use the `-s` flag like `docker compose run binder ./setup.py test -s tests.test_some_specific_test`.
 
 ## MySQL support
 

binder/models.py

@@ -9,7 +9,7 @@
 from decimal import Decimal
 
 from django import forms
-from django.db import models
+from django.db import models, transaction
 from django.db.models import Value
 from django.db.models.fields.files import FieldFile, FileField
 from django.contrib.postgres.fields import CITextField, ArrayField, DateTimeRangeField as DTRangeField
@@ -28,6 +28,7 @@
 from binder.json import jsonloads
 
 from binder.exceptions import BinderRequestError
+from binder.websocket import trigger
 
 from . import history
 
@@ -458,6 +459,8 @@ def __new__(cls, name, bases, attrs):
 
 
 class BinderModel(models.Model, metaclass=BinderModelBase):
+	push_websocket_updates_upon_save = False
+
 	def binder_concrete_fields_as_dict(self, skip_deferred_fields=False):
 		fields = {}
 		deferred_fields = self.get_deferred_fields()
@@ -614,9 +617,19 @@ class Meta:
 		ordering = ['pk']
 
 	def save(self, *args, **kwargs):
+		from binder.views import determine_model_resource_name
 		self.full_clean() # Never allow saving invalid models!
-		return super().save(*args, **kwargs)
-
+		result = super().save(*args, **kwargs)
+		if self.push_websocket_updates_upon_save:
+			transaction.on_commit(lambda: trigger(self.pk, [{ 'auto-updates': determine_model_resource_name(self.__class__.__name__)}]))
+		return result
+
+	def delete(self, *args, **kwargs):
+		from binder.views import determine_model_resource_name
+		result = super().delete(*args, **kwargs)
+		if self.push_websocket_updates_upon_save:
+			transaction.on_commit(lambda: trigger(self.pk, [{ 'auto-updates': determine_model_resource_name(self.__class__.__name__)}]))
+		return result
 
 	# This can be overridden in your model when there are special
 	# validation rules like partial indexes that may need to be

binder/permissions/views.py

@@ -190,6 +190,13 @@ def get_queryset(self, request):
 		return self.scope_view(request, queryset)
 
 
+	@classmethod
+	def get_rooms_for_user(cls, user):
+		if user.has_perm(cls.model._meta.app_label + '.view_' + cls.model.__name__.lower()):
+			return [{ 'auto-updates': cls._model_name() }]
+		else:
+			return []
+
 
 	def _require_model_perm(self, perm_type, request, pk=None):
 		"""

binder/views.py

@@ -342,6 +342,8 @@ def prefix_q_expression(value, prefix, antiprefix=None, model=None):
 			children.append((prefix + '__' + child[0], child[1]))
 	return Q(*children, _connector=value.connector, _negated=value.negated)
 
+def determine_model_resource_name(mn: str):
+	return ''.join((x + '_' if x.islower() and y.isupper() else x.lower() for x, y in zip(mn, mn[1:] + 'x')))
 
 class ModelView(View):
 	# Model this is a view for. Use None for views not tied to a particular model.
@@ -578,9 +580,7 @@ def get_field_filter(self, field_class, reset=False):
 	# Like model._meta.model_name, except it converts camelcase to underscores
 	@classmethod
 	def _model_name(cls):
-		mn = cls.model.__name__
-		return ''.join((x + '_' if x.islower() and y.isupper() else x.lower() for x, y in zip(mn, mn[1:] + 'x')))
-
+		return determine_model_resource_name(cls.model.__name__)
 
 
 	# Use this to instantiate other views you need. It returns a properly initialized view instance.

docs/websockets.md

@@ -4,8 +4,8 @@ Binder.websockets contains functions to connect with a [high-templar](https://gi
 
 ## Flow
 
-The client = a web/native/whatever frontend  
-The websocket server = a high-templar instance  
+The client = a web/native/whatever frontend
+The websocket server = a high-templar instance
 The binder app = a server created with django-binder
 
 - The client needs live updates of certain models.
@@ -24,7 +24,7 @@ The scoping of subscriptions is done through rooms. Roomnames are dictionaries.
 
 There is a chat application for a company. A manager can only view messages of a single location.
 
-The allowed_rooms of a manager of the eindhoven branch could look like 
+The allowed_rooms of a manager of the eindhoven branch could look like
 ```
 [{'location': 'Eindhoven'}]
 ```
@@ -43,9 +43,21 @@ Note: this doesn't mean a client can subscribe to room: `{'location': '*'}` and
 
 If you do really need a room with messages from all locations, just trigger twice: once in the location specific room and one in the location: * room.
 
+## Trigger on saves
+Since sending websocket updates upon saving models is something we often need, there is a 'shortcut' for this.
+If you set `push_websocket_updates_upon_save` to `True` in a model, it will automatically send websocket updates whenever it is saved or deleted.
+
+```python
+class Country(BinderModel):
+    push_websocket_updates_upon_save = True
+    name = models.CharField(unique=True, max_length=100)
+```
+For instance, whenever a `Country` is saved, it will trigger a websocket update to `auto-updates/country` with `data = country.id`.
+
+
 ## Binder setup
 
-The high-templar instance is agnostic of the authentication/datamodel/permissions. The authentication is done by the proxy to /api/bootstrap. The datamodel / permission stuff is all done through rooms and the data that gets sent through it. 
+The high-templar instance is agnostic of the authentication/datamodel/permissions. The authentication is done by the proxy to /api/bootstrap. The datamodel / permission stuff is all done through rooms and the data that gets sent through it.
 
 `binder.websocket` provides 2 helpers for communicating with high-templar.
 
@@ -74,4 +86,3 @@ The RoomController checks every descendant of the ModelView and looks for a  `@c
 ### Trigger
 
 `binder.websocket` provides a `trigger` to the high_templar instance using a POST request. The url for this request is `getattr(settings, 'HIGH_TEMPLAR_URL', 'http://localhost:8002')`. It needs `data, rooms` as args, the data which will be sent in the publish and the rooms it will be publishes to.
-

tests/test_websocket.py

@@ -1,19 +1,22 @@
-from django.test import TestCase, Client
+from django.test import TestCase, TransactionTestCase, Client
 from django.contrib.auth.models import User
 from unittest import mock
 from binder.views import JsonResponse
 from binder.websocket import trigger
 from .testapp.urls import room_controller
-from .testapp.models import Animal, Costume
+from .testapp.models import Animal, Costume, Country
 import requests
 import json
 from django.test import override_settings
 
 
 class MockUser:
-	def __init__(self, costumes):
+	def __init__(self, costumes, permission = ''):
 		self.costumes = costumes
+		self.permission = permission
 
+	def has_perm(self, permission: str):
+		return permission == self.permission
 
 def mock_post_high_templar(*args, **kwargs):
 	return JsonResponse({'ok': True})
@@ -70,6 +73,31 @@ def test_post_succeeds_when_trigger_fails(self):
 
 		self.assertIsNotNone(costume.pk)
 
+	def test_auto_update_rooms(self):
+		user = MockUser([], 'testapp.view_city')
+		rooms = room_controller.list_rooms_for_user(user)
+
+		found_it = False
+		for room in rooms:
+			if 'auto-updates' in room and room['auto-updates'] == 'city':
+				found_it = True
+		self.assertTrue(found_it)
+
+class AutoUpdateTest(TransactionTestCase):
+	@mock.patch('requests.post', side_effect=mock_post_high_templar)
+	@override_settings(HIGH_TEMPLAR_URL="http://localhost:8002")
+	def test_auto_update_trigger(self, mock):
+		country = Country.objects.create(name='YellowLand')
+		mock.assert_called_with('http://localhost:8002/trigger/', data=json.dumps({
+				'data': country.pk,
+				'rooms': [{ 'auto-updates': 'country' }]
+			}))
+		mock.reset_mock()
+		country.delete()
+		mock.assert_called_with('http://localhost:8002/trigger/', data=json.dumps({
+				'data': country.pk,
+				'rooms': [{ 'auto-updates': 'country' }]
+			}))
 
 class TriggerConnectionCloseTest(TestCase):
 	@override_settings(
@@ -92,4 +120,3 @@ def test_trigger_calls_connection_close(self, mock_connection_class):
 		trigger(data, rooms)
 
 		mock_connection.close.assert_called_once()
-

tests/testapp/models/country.py

@@ -3,4 +3,5 @@
 
 
 class Country(BinderModel):
+    push_websocket_updates_upon_save = True
     name = models.CharField(unique=True, max_length=100)