From cdfc9da4d9d5d0836e07e238b763df2eac1583a8 Mon Sep 17 00:00:00 2001
From: Awais <awais.qureshi@arbisoft.com>
Date: Tue, 25 Aug 2015 19:28:51 +0500
Subject: [PATCH] adding validator to make sure course exists in db before
 creating in otto.

---
 lms/djangoapps/commerce/api/v1/serializers.py | 29 +++++++++++++-
 .../commerce/api/v1/tests/test_serializers.py | 24 ++++++++++++
 .../commerce/api/v1/tests/test_views.py       | 38 +++++++++++++++++++
 3 files changed, 90 insertions(+), 1 deletion(-)
 create mode 100644 lms/djangoapps/commerce/api/v1/tests/test_serializers.py

diff --git a/lms/djangoapps/commerce/api/v1/serializers.py b/lms/djangoapps/commerce/api/v1/serializers.py
index fa8c2754f3..a904fa7238 100644
--- a/lms/djangoapps/commerce/api/v1/serializers.py
+++ b/lms/djangoapps/commerce/api/v1/serializers.py
@@ -2,11 +2,17 @@
 from datetime import datetime
 
 import pytz
+from django.utils.translation import ugettext as _
+
+from opaque_keys import InvalidKeyError
+from opaque_keys.edx.keys import CourseKey
 from rest_framework import serializers
 
 from commerce.api.v1.models import Course
 from course_modes.models import CourseMode
 
+from xmodule.modulestore.django import modulestore
+
 
 class CourseModeSerializer(serializers.ModelSerializer):
     """ CourseMode serializer. """
@@ -25,9 +31,30 @@ class CourseModeSerializer(serializers.ModelSerializer):
         fields = ('name', 'currency', 'price', 'sku', 'expires')
 
 
+def validate_course_id(course_id):
+    """
+    Check that course id is valid and exists in modulestore.
+    """
+    try:
+        course_key = CourseKey.from_string(unicode(course_id))
+    except InvalidKeyError:
+        raise serializers.ValidationError(
+            _("{course_id} is not a valid course key.").format(
+                course_id=course_id
+            )
+        )
+
+    if not modulestore().has_course(course_key):
+        raise serializers.ValidationError(
+            _('Course {course_id} does not exist.').format(
+                course_id=course_id
+            )
+        )
+
+
 class CourseSerializer(serializers.Serializer):
     """ Course serializer. """
-    id = serializers.CharField()  # pylint: disable=invalid-name
+    id = serializers.CharField(validators=[validate_course_id])  # pylint: disable=invalid-name
     name = serializers.CharField(read_only=True)
     verification_deadline = serializers.DateTimeField(blank=True)
     modes = CourseModeSerializer(many=True, allow_add_remove=True)
diff --git a/lms/djangoapps/commerce/api/v1/tests/test_serializers.py b/lms/djangoapps/commerce/api/v1/tests/test_serializers.py
new file mode 100644
index 0000000000..93bcb9aee3
--- /dev/null
+++ b/lms/djangoapps/commerce/api/v1/tests/test_serializers.py
@@ -0,0 +1,24 @@
+""" Commerce API v1 serializer tests. """
+from django.test import TestCase
+
+from commerce.api.v1.serializers import serializers, validate_course_id
+
+
+class CourseValidatorTests(TestCase):
+    """ Tests for Course Validator method. """
+
+    def test_validate_course_id_with_non_existent_course(self):
+        """ Verify a validator checking non-existent courses."""
+        course_key = 'non/existing/keyone'
+
+        error_msg = u"Course {} does not exist.".format(course_key)
+        with self.assertRaisesRegexp(serializers.ValidationError, error_msg):
+            validate_course_id(course_key)
+
+    def test_validate_course_id_with_invalid_key(self):
+        """ Verify a validator checking invalid course keys."""
+        course_key = 'invalidkey'
+
+        error_msg = u"{} is not a valid course key.".format(course_key)
+        with self.assertRaisesRegexp(serializers.ValidationError, error_msg):
+            validate_course_id(course_key)
diff --git a/lms/djangoapps/commerce/api/v1/tests/test_views.py b/lms/djangoapps/commerce/api/v1/tests/test_views.py
index 365a286b0d..eb43f7a660 100644
--- a/lms/djangoapps/commerce/api/v1/tests/test_views.py
+++ b/lms/djangoapps/commerce/api/v1/tests/test_views.py
@@ -267,3 +267,41 @@ class CourseRetrieveUpdateViewTests(CourseApiViewTestMixin, ModuleStoreTestCase)
         """ Verify the view supports creating a course when authenticated with the API header key. """
         self.client.logout()
         self.assert_can_create_course(HTTP_X_EDX_API_KEY=settings.EDX_API_KEY)
+
+    def test_create_with_non_existent_course(self):
+        """ Verify the API does not allow data to be created for courses that do not exist. """
+
+        permissions = Permission.objects.filter(name__in=('Can add course mode', 'Can change course mode'))
+        for permission in permissions:
+            self.user.user_permissions.add(permission)
+
+        expected_modes = [
+            CourseMode(
+                mode_slug=u'honor',
+                min_price=150, currency=u'USD',
+                sku=u'ABC123'
+            )
+        ]
+
+        course_key = 'non/existing/key'
+
+        course_dict = {
+            u'id': unicode(course_key),
+            u'name': unicode('Non Existing Course'),
+            u'verification_deadline': None,
+            u'modes': [self._serialize_course_mode(mode) for mode in expected_modes]
+        }
+
+        path = reverse('commerce_api:v1:courses:retrieve_update', args=[unicode(course_key)])
+
+        response = self.client.put(path, json.dumps(course_dict), content_type=JSON_CONTENT_TYPE)
+        self.assertEqual(response.status_code, 400)
+
+        expected_dict = {
+            'id': [
+                u'Course {} does not exist.'.format(
+                    course_key
+                )
+            ]
+        }
+        self.assertDictEqual(expected_dict, json.loads(response.content))