Add a django-rest-framework APIView that supports reading/writing the current value of a configuration model

common/djangoapps/config_models/models.py

@@ -93,6 +93,8 @@ class ConfigurationModel(models.Model):
         """
         Clear the cached value when saving a new configuration entry
         """
+        # Always create a new entry, instead of updating an existing model
+        self.pk = None
         super(ConfigurationModel, self).save(*args, **kwargs)
         cache.delete(self.cache_key_name(*[getattr(self, key) for key in self.KEY_FIELDS]))
         if self.KEY_FIELDS:

common/djangoapps/config_models/tests.py

@@ -7,10 +7,13 @@ import ddt
 from django.contrib.auth.models import User
 from django.db import models
 from django.test import TestCase
+from rest_framework.test import APIRequestFactory
+
 from freezegun import freeze_time
 
-from mock import patch
+from mock import patch, Mock
 from config_models.models import ConfigurationModel
+from config_models.views import ConfigurationModelCurrentAPIView
 
 
 class ExampleConfig(ConfigurationModel):
@@ -92,6 +95,14 @@ class ConfigurationModelTests(TestCase):
         self.assertEqual(rows[1].string_field, 'first')
         self.assertEqual(rows[1].is_active, False)
 
+    def test_always_insert(self, mock_cache):
+        config = ExampleConfig(changed_by=self.user, string_field='first')
+        config.save()
+        config.string_field = 'second'
+        config.save()
+
+        self.assertEquals(2, ExampleConfig.objects.all().count())
+
 
 class ExampleKeyedConfig(ConfigurationModel):
     """
@@ -282,3 +293,81 @@ class KeyedConfigurationModelTests(TestCase):
         fake_result = [('a', 'b'), ('c', 'd')]
         mock_cache.get.return_value = fake_result
         self.assertEquals(ExampleKeyedConfig.key_values(), fake_result)
+
+
+@ddt.ddt
+class ConfigurationModelAPITests(TestCase):
+    def setUp(self):
+        self.factory = APIRequestFactory()
+        self.user = User.objects.create_user(
+            username='test_user',
+            email='test_user@example.com',
+            password='test_pass',
+        )
+        self.user.is_superuser = True
+        self.user.save()
+
+        self.current_view = ConfigurationModelCurrentAPIView.as_view(model=ExampleConfig)
+
+        # Disable caching while testing the API
+        patcher = patch('config_models.models.cache', Mock(get=Mock(return_value=None)))
+        patcher.start()
+        self.addCleanup(patcher.stop)
+
+    def test_insert(self):
+        self.assertEquals("", ExampleConfig.current().string_field)
+
+        request = self.factory.post('/config/ExampleConfig', {"string_field": "string_value"})
+        request.user = self.user
+        response = self.current_view(request)
+
+        self.assertEquals("string_value", ExampleConfig.current().string_field)
+        self.assertEquals(self.user, ExampleConfig.current().changed_by)
+
+    def test_multiple_inserts(self):
+        for i in xrange(3):
+            self.assertEquals(i, ExampleConfig.objects.all().count())
+
+            request = self.factory.post('/config/ExampleConfig', {"string_field": str(i)})
+            request.user = self.user
+            response = self.current_view(request)
+            self.assertEquals(201, response.status_code)
+
+            self.assertEquals(i+1, ExampleConfig.objects.all().count())
+            self.assertEquals(str(i), ExampleConfig.current().string_field)
+
+    def test_get_current(self):
+        request = self.factory.get('/config/ExampleConfig')
+        request.user = self.user
+        response = self.current_view(request)
+        self.assertEquals('', response.data['string_field'])
+        self.assertEquals(10, response.data['int_field'])
+        self.assertEquals(None, response.data['changed_by'])
+        self.assertEquals(False, response.data['enabled'])
+        self.assertEquals(None, response.data['change_date'])
+
+        ExampleConfig(string_field='string_value', int_field=20).save()
+
+        response = self.current_view(request)
+        self.assertEquals('string_value', response.data['string_field'])
+        self.assertEquals(20, response.data['int_field'])
+
+    @ddt.data(
+        ('get', [], 200),
+        ('post', [{'string_field': 'string_value', 'int_field': 10}], 201),
+    )
+    @ddt.unpack
+    def test_permissions(self, method, args, status_code):
+        request = getattr(self.factory, method)('/config/ExampleConfig', *args)
+
+        request.user = User.objects.create_user(
+            username='no-perms',
+            email='no-perms@example.com',
+            password='no-perms',
+        )
+        response = self.current_view(request)
+        self.assertEquals(403, response.status_code)
+
+        request.user = self.user
+        response = self.current_view(request)
+        self.assertEquals(status_code, response.status_code)

common/djangoapps/config_models/views.py

@@ -0,0 +1,44 @@
+from rest_framework.generics import CreateAPIView, RetrieveAPIView
+from rest_framework.permissions import DjangoModelPermissions
+from rest_framework.authentication import SessionAuthentication
+from rest_framework.serializers import ModelSerializer
+
+
+class ReadableOnlyByAuthors(DjangoModelPermissions):
+    perms_map = DjangoModelPermissions.perms_map.copy()
+    perms_map['GET'] = perms_map['OPTIONS'] = perms_map['HEAD'] = perms_map['POST']
+
+
+class ConfigurationModelCurrentAPIView(CreateAPIView, RetrieveAPIView):
+    """
+    This view allows an authenticated user with the appropriate model permissions
+    to read and write the current configuration for the specified `model`.
+
+    Like other APIViews, you can use this by using a url pattern similar to the following::
+
+        url(r'config/example_config$', ConfigurationModelCurrentAPIView.as_view(model=ExampleConfig))
+    """
+    authentication_classes = (SessionAuthentication,)
+    permission_classes = (ReadableOnlyByAuthors,)
+    model = None
+
+    def get_queryset(self):
+        return self.model.objects.all()
+
+    def get_object(self):
+        # Return the currently active configuration
+        return self.model.current()
+
+    def get_serializer_class(self):
+        if self.serializer_class is None:
+            class AutoConfigModelSerializer(ModelSerializer):
+                class Meta:
+                    model = self.model
+
+            self.serializer_class = AutoConfigModelSerializer
+
+        return self.serializer_class
+
+    def perform_create(self, serializer):
+        # Set the requesting user as the one who is updating the configuration
+        serializer.save(changed_by = self.request.user)