Override field data within the XBlock runtime

Resolves an issue preventing students in self-paced courses from seeing all available discussion modules. ECOM-3733.

cms/envs/aws.py

@@ -283,6 +283,17 @@ else:
 DATABASES = AUTH_TOKENS['DATABASES']
 
 MODULESTORE = convert_module_store_setting_if_needed(AUTH_TOKENS.get('MODULESTORE', MODULESTORE))
+
+MODULESTORE_FIELD_OVERRIDE_PROVIDERS = ENV_TOKENS.get(
+    'MODULESTORE_FIELD_OVERRIDE_PROVIDERS',
+    MODULESTORE_FIELD_OVERRIDE_PROVIDERS
+)
+
+XBLOCK_FIELD_DATA_WRAPPERS = ENV_TOKENS.get(
+    'XBLOCK_FIELD_DATA_WRAPPERS',
+    XBLOCK_FIELD_DATA_WRAPPERS
+)
+
 CONTENTSTORE = AUTH_TOKENS['CONTENTSTORE']
 DOC_STORE_CONFIG = AUTH_TOKENS['DOC_STORE_CONFIG']
 # Datadog for events!

cms/envs/common.py

@@ -383,6 +383,9 @@ XBLOCK_MIXINS = (
 
 XBLOCK_SELECT_FUNCTION = prefer_xmodules
 
+# Paths to wrapper methods which should be applied to every XBlock's FieldData.
+XBLOCK_FIELD_DATA_WRAPPERS = ()
+
 ############################ Modulestore Configuration ################################
 MODULESTORE_BRANCH = 'draft-preferred'
 
@@ -417,6 +420,10 @@ MODULESTORE = {
     }
 }
 
+# Modulestore-level field override providers. These field override providers don't
+# require student context.
+MODULESTORE_FIELD_OVERRIDE_PROVIDERS = ()
+
 #################### Python sandbox ############################################
 
 CODE_JAIL = {

common/lib/xmodule/xmodule/modulestore/__init__.py

@@ -1160,7 +1160,7 @@ class ModuleStoreReadBase(BulkOperationsMixin, ModuleStoreRead):
         contentstore=None,
         doc_store_config=None,  # ignore if passed up
         metadata_inheritance_cache_subsystem=None, request_cache=None,
-        xblock_mixins=(), xblock_select=None, disabled_xblock_types=(),  # pylint: disable=bad-continuation
+        xblock_mixins=(), xblock_select=None, xblock_field_data_wrappers=(), disabled_xblock_types=(),  # pylint: disable=bad-continuation
         # temporary parms to enable backward compatibility. remove once all envs migrated
         db=None, collection=None, host=None, port=None, tz_aware=True, user=None, password=None,
         # allow lower level init args to pass harmlessly
@@ -1177,6 +1177,7 @@ class ModuleStoreReadBase(BulkOperationsMixin, ModuleStoreRead):
         self.request_cache = request_cache
         self.xblock_mixins = xblock_mixins
         self.xblock_select = xblock_select
+        self.xblock_field_data_wrappers = xblock_field_data_wrappers
         self.disabled_xblock_types = disabled_xblock_types
         self.contentstore = contentstore
 

common/lib/xmodule/xmodule/modulestore/django.py

@@ -120,11 +120,25 @@ def load_function(path):
     """
     Load a function by name.
 
-    path is a string of the form "path.to.module.function"
-    returns the imported python object `function` from `path.to.module`
+    Arguments:
+        path: String of the form 'path.to.module.function'. Strings of the form
+            'path.to.module:Class.function' are also valid.
+
+    Returns:
+        The imported object 'function'.
     """
-    module_path, _, name = path.rpartition('.')
-    return getattr(import_module(module_path), name)
+    if ':' in path:
+        module_path, _, method_path = path.rpartition(':')
+        module = import_module(module_path)
+
+        class_name, method_name = method_path.split('.')
+        _class = getattr(module, class_name)
+        function = getattr(_class, method_name)
+    else:
+        module_path, _, name = path.rpartition('.')
+        function = getattr(import_module(module_path), name)
+
+    return function
 
 
 def create_modulestore_instance(
@@ -179,12 +193,15 @@ def create_modulestore_instance(
     else:
         disabled_xblock_types = ()
 
+    xblock_field_data_wrappers = [load_function(path) for path in settings.XBLOCK_FIELD_DATA_WRAPPERS]
+
     return class_(
         contentstore=content_store,
         metadata_inheritance_cache_subsystem=metadata_inheritance_cache,
         request_cache=request_cache,
         xblock_mixins=getattr(settings, 'XBLOCK_MIXINS', ()),
         xblock_select=getattr(settings, 'XBLOCK_SELECT_FUNCTION', None),
+        xblock_field_data_wrappers=xblock_field_data_wrappers,
         disabled_xblock_types=disabled_xblock_types,
         doc_store_config=doc_store_config,
         i18n_service=i18n_service or ModuleI18nService(),

common/lib/xmodule/xmodule/modulestore/inheritance.py

@@ -218,6 +218,17 @@ class InheritanceMixin(XBlockMixin):
         default=False
     )
 
+    self_paced = Boolean(
+        display_name=_('Self Paced'),
+        help=_(
+            'Set this to "true" to mark this course as self-paced. Self-paced courses do not have '
+            'due dates for assignments, and students can progress through the course at any rate before '
+            'the course ends.'
+        ),
+        default=False,
+        scope=Scope.settings
+    )
+
 
 def compute_inherited_metadata(descriptor):
     """Given a descriptor, traverse all of its descendants and do metadata

common/lib/xmodule/xmodule/modulestore/mongo/base.py

@@ -12,27 +12,24 @@ structure:
 }
 """
 
-import pymongo
-import sys
-import logging
 import copy
+from datetime import datetime
+from importlib import import_module
+import logging
+import pymongo
 import re
+import sys
 from uuid import uuid4
 
 from bson.son import SON
-from datetime import datetime
+from contracts import contract, new_contract
 from fs.osfs import OSFS
 from mongodb_proxy import autoretry_read
-from path import Path as path
-from pytz import UTC
-from contracts import contract, new_contract
-
-from importlib import import_module
 from opaque_keys.edx.keys import UsageKey, CourseKey, AssetKey
-from opaque_keys.edx.locations import Location, BlockUsageLocator
-from opaque_keys.edx.locations import SlashSeparatedCourseKey
+from opaque_keys.edx.locations import Location, BlockUsageLocator, SlashSeparatedCourseKey
 from opaque_keys.edx.locator import CourseLocator, LibraryLocator
-
+from path import Path as path
+from pytz import UTC
 from xblock.core import XBlock
 from xblock.exceptions import InvalidScopeError
 from xblock.fields import Scope, ScopeIds, Reference, ReferenceList, ReferenceValueDict
@@ -54,6 +51,7 @@ from xmodule.modulestore.xml import CourseLocationManager
 from xmodule.modulestore.store_utilities import DETACHED_XBLOCK_TYPES
 from xmodule.services import SettingsService
 
+
 log = logging.getLogger(__name__)
 
 new_contract('CourseKey', CourseKey)
@@ -318,6 +316,9 @@ class CachingDescriptorSystem(MakoDescriptorSystem, EditInfoRuntimeMixin):
                         ).replace(tzinfo=UTC)
                     module._edit_info['published_by'] = raw_metadata.get('published_by')
 
+                for wrapper in self.modulestore.xblock_field_data_wrappers:
+                    module._field_data = wrapper(module, module._field_data)  # pylint: disable=protected-access
+
                 # decache any computed pending field settings
                 module.save()
                 return module

common/lib/xmodule/xmodule/modulestore/split_mongo/caching_descriptor_system.py

 import sys
 import logging
+
 from contracts import contract, new_contract
 from fs.osfs import OSFS
 from lazy import lazy
@@ -7,6 +8,7 @@ from xblock.runtime import KvsFieldData, KeyValueStore
 from xblock.fields import ScopeIds
 from xblock.core import XBlock
 from opaque_keys.edx.locator import BlockUsageLocator, LocalId, CourseLocator, LibraryLocator, DefinitionLocator
+
 from xmodule.library_tools import LibraryToolsService
 from xmodule.mako_module import MakoDescriptorSystem
 from xmodule.error_module import ErrorDescriptor
@@ -263,6 +265,10 @@ class CachingDescriptorSystem(MakoDescriptorSystem, EditInfoRuntimeMixin):
         module.update_version = edit_info.update_version
         module.source_version = edit_info.source_version
         module.definition_locator = DefinitionLocator(block_key.type, definition_id)
+
+        for wrapper in self.modulestore.xblock_field_data_wrappers:
+            module._field_data = wrapper(module, module._field_data)  # pylint: disable=protected-access
+
         # decache any pending field settings
         module.save()
 

lms/djangoapps/courseware/field_overrides.py

@@ -14,17 +14,20 @@ package and is used to wrap the `authored_data` when constructing an
 `LmsFieldData`.  This means overrides will be in effect for all scopes covered
 by `authored_data`, e.g. course content and settings stored in Mongo.
 """
-import threading
-
 from abc import ABCMeta, abstractmethod
 from contextlib import contextmanager
+import threading
+
 from django.conf import settings
-from request_cache.middleware import RequestCache
 from xblock.field_data import FieldData
+
+from request_cache.middleware import RequestCache
 from xmodule.modulestore.inheritance import InheritanceMixin
 
+
 NOTSET = object()
-ENABLED_OVERRIDE_PROVIDERS_KEY = "courseware.field_overrides.enabled_providers.{course_id}"
+ENABLED_OVERRIDE_PROVIDERS_KEY = u'courseware.field_overrides.enabled_providers.{course_id}'
+ENABLED_MODULESTORE_OVERRIDE_PROVIDERS_KEY = u'courseware.modulestore_field_overrides.enabled_providers.{course_id}'
 
 
 def resolve_dotted(name):
@@ -46,6 +49,88 @@ def resolve_dotted(name):
     return target
 
 
+def _lineage(block):
+    """
+    Returns an iterator over all ancestors of the given block, starting with
+    its immediate parent and ending at the root of the block tree.
+    """
+    parent = block.get_parent()
+    while parent:
+        yield parent
+        parent = parent.get_parent()
+
+
+class _OverridesDisabled(threading.local):
+    """
+    A thread local used to manage state of overrides being disabled or not.
+    """
+    disabled = ()
+
+
+_OVERRIDES_DISABLED = _OverridesDisabled()
+
+
+@contextmanager
+def disable_overrides():
+    """
+    A context manager which disables field overrides inside the context of a
+    `with` statement, allowing code to get at the `original` value of a field.
+    """
+    prev = _OVERRIDES_DISABLED.disabled
+    _OVERRIDES_DISABLED.disabled += (True,)
+    yield
+    _OVERRIDES_DISABLED.disabled = prev
+
+
+def overrides_disabled():
+    """
+    Checks to see whether overrides are disabled in the current context.
+    Returns a boolean value.  See `disable_overrides`.
+    """
+    return bool(_OVERRIDES_DISABLED.disabled)
+
+
+class FieldOverrideProvider(object):
+    """
+    Abstract class which defines the interface that a `FieldOverrideProvider`
+    must provide.  In general, providers should derive from this class, but
+    it's not strictly necessary as long as they correctly implement this
+    interface.
+
+    A `FieldOverrideProvider` implementation is only responsible for looking up
+    field overrides. To set overrides, there will be a domain specific API for
+    the concrete override implementation being used.
+    """
+    __metaclass__ = ABCMeta
+
+    def __init__(self, user):
+        self.user = user
+
+    @abstractmethod
+    def get(self, block, name, default):  # pragma no cover
+        """
+        Look for an override value for the field named `name` in `block`.
+        Returns the overridden value or `default` if no override is found.
+        """
+        raise NotImplementedError
+
+    @abstractmethod
+    def enabled_for(self, course):  # pragma no cover
+        """
+        Return True if this provider should be enabled for a given course,
+        and False otherwise.
+
+        Concrete implementations are responsible for implementing this method.
+
+        Arguments:
+          course (CourseModule or None)
+
+        Returns:
+          bool
+        """
+        return False
+
+
 class OverrideFieldData(FieldData):
     """
     A :class:`~xblock.field_data.FieldData` which wraps another `FieldData`
@@ -171,83 +256,54 @@ class OverrideFieldData(FieldData):
         return self.fallback.default(block, name)
 
 
-class _OverridesDisabled(threading.local):
-    """
-    A thread local used to manage state of overrides being disabled or not.
-    """
-    disabled = ()
-
-
-_OVERRIDES_DISABLED = _OverridesDisabled()
-
-
-@contextmanager
-def disable_overrides():
-    """
-    A context manager which disables field overrides inside the context of a
-    `with` statement, allowing code to get at the `original` value of a field.
-    """
-    prev = _OVERRIDES_DISABLED.disabled
-    _OVERRIDES_DISABLED.disabled += (True,)
-    yield
-    _OVERRIDES_DISABLED.disabled = prev
-
-
-def overrides_disabled():
-    """
-    Checks to see whether overrides are disabled in the current context.
-    Returns a boolean value.  See `disable_overrides`.
-    """
-    return bool(_OVERRIDES_DISABLED.disabled)
+class OverrideModulestoreFieldData(OverrideFieldData):
+    """Apply field data overrides at the modulestore level. No student context required."""
 
+    @classmethod
+    def wrap(cls, block, field_data):  # pylint: disable=arguments-differ
+        """
+        Returns an instance of FieldData wrapped by FieldOverrideProviders which
+        extend read-only functionality. If no MODULESTORE_FIELD_OVERRIDE_PROVIDERS
+        are configured, an unwrapped FieldData instance is returned.
 
-class FieldOverrideProvider(object):
-    """
-    Abstract class which defines the interface that a `FieldOverrideProvider`
-    must provide.  In general, providers should derive from this class, but
-    it's not strictly necessary as long as they correctly implement this
-    interface.
+        Arguments:
+            block: An XBlock
+            field_data: An instance of FieldData to be wrapped
+        """
+        if cls.provider_classes is None:
+            cls.provider_classes = [
+                resolve_dotted(name) for name in settings.MODULESTORE_FIELD_OVERRIDE_PROVIDERS
+            ]
 
-    A `FieldOverrideProvider` implementation is only responsible for looking up
-    field overrides. To set overrides, there will be a domain specific API for
-    the concrete override implementation being used.
-    """
-    __metaclass__ = ABCMeta
+        enabled_providers = cls._providers_for_block(block)
+        if enabled_providers:
+            return cls(field_data, enabled_providers)
 
-    def __init__(self, user):
-        self.user = user
+        return field_data
 
-    @abstractmethod
-    def get(self, block, name, default):  # pragma no cover
-        """
-        Look for an override value for the field named `name` in `block`.
-        Returns the overridden value or `default` if no override is found.
+    @classmethod
+    def _providers_for_block(cls, block):
         """
-        raise NotImplementedError
+        Computes a list of enabled providers based on the given XBlock.
+        The result is cached per request to avoid the overhead incurred
+        by filtering override providers hundreds of times.
 
-    @abstractmethod
-    def enabled_for(self, course):  # pragma no cover
+        Arguments:
+            block: An XBlock
         """
-        Return True if this provider should be enabled for a given course,
-        and False otherwise.
-
-        Concrete implementations are responsible for implementing this method.
+        course_id = unicode(block.location.course_key)
+        cache_key = ENABLED_MODULESTORE_OVERRIDE_PROVIDERS_KEY.format(course_id=course_id)
 
-        Arguments:
-          course (CourseModule or None)
+        request_cache = RequestCache.get_request_cache()
+        enabled_providers = request_cache.data.get(cache_key)
 
-        Returns:
-          bool
-        """
-        return False
+        if enabled_providers is None:
+            enabled_providers = [
+                provider_class for provider_class in cls.provider_classes if provider_class.enabled_for(block)
+            ]
+            request_cache.data[cache_key] = enabled_providers
 
+        return enabled_providers
 
-def _lineage(block):
-    """
-    Returns an iterator over all ancestors of the given block, starting with
-    its immediate parent and ending at the root of the block tree.
-    """
-    parent = block.get_parent()
-    while parent:
-        yield parent
-        parent = parent.get_parent()
+    def __init__(self, fallback, providers):
+        super(OverrideModulestoreFieldData, self).__init__(None, fallback, providers)

lms/djangoapps/courseware/self_paced_overrides.py

@@ -20,9 +20,10 @@ class SelfPacedDateOverrideProvider(FieldOverrideProvider):
         # Remove release dates for course content
         if name == 'start' and block.category != 'course':
             return None
+
         return default
 
     @classmethod
-    def enabled_for(cls, course):
+    def enabled_for(cls, block):
         """This provider is enabled for self-paced courses only."""
-        return course is not None and course.self_paced and SelfPacedConfiguration.current().enabled
+        return block is not None and block.self_paced and SelfPacedConfiguration.current().enabled

lms/djangoapps/courseware/tests/test_field_overrides.py

 """
 Tests for `field_overrides` module.
 """
+# pylint: disable=missing-docstring
 import unittest
 from nose.plugins.attrib import attr
 
@@ -10,16 +11,39 @@ from xmodule.modulestore.tests.factories import CourseFactory
 from xmodule.modulestore.tests.django_utils import SharedModuleStoreTestCase
 
 from ..field_overrides import (
+    resolve_dotted,
     disable_overrides,
     FieldOverrideProvider,
     OverrideFieldData,
-    resolve_dotted,
+    OverrideModulestoreFieldData,
 )
 
 
 TESTUSER = "testuser"
 
 
+class TestOverrideProvider(FieldOverrideProvider):
+    """
+    A concrete implementation of `FieldOverrideProvider` for testing.
+    """
+    def get(self, block, name, default):
+        if self.user:
+            assert self.user is TESTUSER
+
+        assert block == 'block'
+
+        if name == 'foo':
+            return 'fu'
+        elif name == 'oh':
+            return 'man'
+
+        return default
+
+    @classmethod
+    def enabled_for(cls, course):
+        return True
+
+
 @attr('shard_1')
 @override_settings(FIELD_OVERRIDE_PROVIDERS=(
     'courseware.tests.test_field_overrides.TestOverrideProvider',))
@@ -101,6 +125,31 @@ class OverrideFieldDataTests(SharedModuleStoreTestCase):
 
 
 @attr('shard_1')
+@override_settings(
+    MODULESTORE_FIELD_OVERRIDE_PROVIDERS=['courseware.tests.test_field_overrides.TestOverrideProvider']
+)
+class OverrideModulestoreFieldDataTests(OverrideFieldDataTests):
+    def setUp(self):
+        super(OverrideModulestoreFieldDataTests, self).setUp()
+        OverrideModulestoreFieldData.provider_classes = None
+
+    def tearDown(self):
+        super(OverrideModulestoreFieldDataTests, self).tearDown()
+        OverrideModulestoreFieldData.provider_classes = None
+
+    def make_one(self):
+        return OverrideModulestoreFieldData.wrap(self.course, DictFieldData({
+            'foo': 'bar',
+            'bees': 'knees',
+        }))
+
+    @override_settings(MODULESTORE_FIELD_OVERRIDE_PROVIDERS=[])
+    def test_no_overrides_configured(self):
+        data = self.make_one()
+        self.assertIsInstance(data, DictFieldData)
+
+
+@attr('shard_1')
 class ResolveDottedTests(unittest.TestCase):
     """
     Tests for `resolve_dotted`.
@@ -121,24 +170,6 @@ class ResolveDottedTests(unittest.TestCase):
         )
 
 
-class TestOverrideProvider(FieldOverrideProvider):
-    """
-    A concrete implementation of `FieldOverrideProvider` for testing.
-    """
-    def get(self, block, name, default):
-        assert self.user is TESTUSER
-        assert block == 'block'
-        if name == 'foo':
-            return 'fu'
-        if name == 'oh':
-            return 'man'
-        return default
-
-    @classmethod
-    def enabled_for(cls, course):
-        return True
-
-
 def inject_field_overrides(blocks, course, user):
     """
     Apparently the test harness doesn't use LmsFieldStorage, and I'm

lms/djangoapps/courseware/tests/test_self_paced_overrides.py

-"""
-Tests for self-paced course due date overrides.
-"""
-
+"""Tests for self-paced course due date overrides."""
+# pylint: disable=missing-docstring
 import datetime
 import pytz
 
@@ -11,17 +9,17 @@ from mock import patch
 
 from courseware.tests.factories import BetaTesterFactory
 from courseware.access import has_access
-
 from lms.djangoapps.ccx.tests.test_overrides import inject_field_overrides
-from lms.djangoapps.courseware.field_overrides import OverrideFieldData
+from lms.djangoapps.django_comment_client.utils import get_accessible_discussion_modules
+from lms.djangoapps.courseware.field_overrides import OverrideFieldData, OverrideModulestoreFieldData
 from openedx.core.djangoapps.self_paced.models import SelfPacedConfiguration
-
 from xmodule.modulestore.tests.django_utils import ModuleStoreTestCase
 from xmodule.modulestore.tests.factories import CourseFactory, ItemFactory
 
 
 @override_settings(
-    FIELD_OVERRIDE_PROVIDERS=('courseware.self_paced_overrides.SelfPacedDateOverrideProvider',)
+    XBLOCK_FIELD_DATA_WRAPPERS=['lms.djangoapps.courseware.field_overrides:OverrideModulestoreFieldData.wrap'],
+    MODULESTORE_FIELD_OVERRIDE_PROVIDERS=['courseware.self_paced_overrides.SelfPacedDateOverrideProvider'],
 )
 class SelfPacedDateOverrideTest(ModuleStoreTestCase):
     """
@@ -29,14 +27,19 @@ class SelfPacedDateOverrideTest(ModuleStoreTestCase):
     """
 
     def setUp(self):
-        SelfPacedConfiguration(enabled=True).save()
         super(SelfPacedDateOverrideTest, self).setUp()
-        self.due_date = datetime.datetime(2015, 5, 26, 8, 30, 00).replace(tzinfo=tzutc())
+
+        SelfPacedConfiguration(enabled=True).save()
+
         self.non_staff_user, __ = self.create_non_staff_user()
+        self.now = datetime.datetime.now(pytz.UTC).replace(microsecond=0)
+        self.future = self.now + datetime.timedelta(days=30)
 
     def tearDown(self):
         super(SelfPacedDateOverrideTest, self).tearDown()
+
         OverrideFieldData.provider_classes = None
+        OverrideModulestoreFieldData.provider_classes = None
 
     def setup_course(self, **course_kwargs):
         """Set up a course with provided course attributes.
@@ -45,22 +48,39 @@ class SelfPacedDateOverrideTest(ModuleStoreTestCase):
         overrides are correctly applied for both blocks.
         """
         course = CourseFactory.create(**course_kwargs)
-        section = ItemFactory.create(parent=course, due=self.due_date)
+        section = ItemFactory.create(parent=course, due=self.now)
         inject_field_overrides((course, section), course, self.user)
         return (course, section)
 
-    def test_instructor_paced(self):
+    def create_discussion_modules(self, parent):
+        # Create a released discussion module
+        ItemFactory.create(
+            parent=parent,
+            category='discussion',
+            display_name='released',
+            start=self.now,
+        )
+
+        # Create a scheduled discussion module
+        ItemFactory.create(
+            parent=parent,
+            category='discussion',
+            display_name='scheduled',
+            start=self.future,
+        )
+
+    def test_instructor_paced_due_date(self):
         __, ip_section = self.setup_course(display_name="Instructor Paced Course", self_paced=False)
-        self.assertEqual(self.due_date, ip_section.due)
+        self.assertEqual(ip_section.due, self.now)
 
-    def test_self_paced(self):
+    def test_self_paced_due_date(self):
         __, sp_section = self.setup_course(display_name="Self-Paced Course", self_paced=True)
         self.assertIsNone(sp_section.due)
 
-    def test_self_paced_disabled(self):
+    def test_self_paced_disabled_due_date(self):
         SelfPacedConfiguration(enabled=False).save()
         __, sp_section = self.setup_course(display_name="Self-Paced Course", self_paced=True)
-        self.assertEqual(self.due_date, sp_section.due)
+        self.assertEqual(sp_section.due, self.now)
 
     @patch.dict('courseware.access.settings.FEATURES', {'DISABLE_START_DATES': False})
     def test_course_access_to_beta_users(self):
@@ -89,3 +109,34 @@ class SelfPacedDateOverrideTest(ModuleStoreTestCase):
         # Verify beta tester can access the course as well as the course sections
         self.assertTrue(has_access(beta_tester, 'load', self_paced_course))
         self.assertTrue(has_access(beta_tester, 'load', self_paced_section, self_paced_course.id))
+
+    @patch.dict('courseware.access.settings.FEATURES', {'DISABLE_START_DATES': False})
+    def test_instructor_paced_discussion_module_visibility(self):
+        """
+        Verify that discussion modules scheduled for release in the future are
+        not visible to students in an instructor-paced course.
+        """
+        course, section = self.setup_course(start=self.now, self_paced=False)
+        self.create_discussion_modules(section)
+
+        # Only the released module should be visible when the course is instructor-paced.
+        modules = get_accessible_discussion_modules(course, self.non_staff_user)
+        self.assertTrue(
+            all(module.display_name == 'released' for module in modules)
+        )
+
+    @patch.dict('courseware.access.settings.FEATURES', {'DISABLE_START_DATES': False})
+    def test_self_paced_discussion_module_visibility(self):
+        """
+        Regression test. Verify that discussion modules scheduled for release
+        in the future are visible to students in a self-paced course.
+        """
+        course, section = self.setup_course(start=self.now, self_paced=True)
+        self.create_discussion_modules(section)
+
+        # The scheduled module should be visible when the course is self-paced.
+        modules = get_accessible_discussion_modules(course, self.non_staff_user)
+        self.assertEqual(len(modules), 2)
+        self.assertTrue(
+            any(module.display_name == 'scheduled' for module in modules)
+        )

lms/envs/aws.py

@@ -389,7 +389,7 @@ if FEATURES.get('ENABLE_CORS_HEADERS') or FEATURES.get('ENABLE_CROSS_DOMAIN_CSRF
     CROSS_DOMAIN_CSRF_COOKIE_DOMAIN = ENV_TOKENS.get('CROSS_DOMAIN_CSRF_COOKIE_DOMAIN')
 
 
-# Field overrides.  To use the IDDE feature, add
+# Field overrides. To use the IDDE feature, add
 # 'courseware.student_field_overrides.IndividualStudentOverrideProvider'.
 FIELD_OVERRIDE_PROVIDERS = tuple(ENV_TOKENS.get('FIELD_OVERRIDE_PROVIDERS', []))
 
@@ -406,6 +406,16 @@ if 'DJFS' in AUTH_TOKENS and AUTH_TOKENS['DJFS'] is not None:
 ############### Module Store Items ##########
 HOSTNAME_MODULESTORE_DEFAULT_MAPPINGS = ENV_TOKENS.get('HOSTNAME_MODULESTORE_DEFAULT_MAPPINGS', {})
 
+MODULESTORE_FIELD_OVERRIDE_PROVIDERS = ENV_TOKENS.get(
+    'MODULESTORE_FIELD_OVERRIDE_PROVIDERS',
+    MODULESTORE_FIELD_OVERRIDE_PROVIDERS
+)
+
+XBLOCK_FIELD_DATA_WRAPPERS = ENV_TOKENS.get(
+    'XBLOCK_FIELD_DATA_WRAPPERS',
+    XBLOCK_FIELD_DATA_WRAPPERS
+)
+
 ############### Mixed Related(Secure/Not-Secure) Items ##########
 LMS_SEGMENT_KEY = AUTH_TOKENS.get('SEGMENT_KEY')
 
@@ -693,7 +703,11 @@ if FEATURES.get('INDIVIDUAL_DUE_DATES'):
     )
 
 ##### Self-Paced Course Due Dates #####
-FIELD_OVERRIDE_PROVIDERS += (
+XBLOCK_FIELD_DATA_WRAPPERS += (
+    'lms.djangoapps.courseware.field_overrides:OverrideModulestoreFieldData.wrap',
+)
+
+MODULESTORE_FIELD_OVERRIDE_PROVIDERS += (
     'courseware.self_paced_overrides.SelfPacedDateOverrideProvider',
 )
 

lms/envs/common.py

@@ -694,6 +694,9 @@ XBLOCK_MIXINS = (LmsBlockMixin, InheritanceMixin, XModuleMixin, EditInfoMixin)
 # Allow any XBlock in the LMS
 XBLOCK_SELECT_FUNCTION = prefer_xmodules
 
+# Paths to wrapper methods which should be applied to every XBlock's FieldData.
+XBLOCK_FIELD_DATA_WRAPPERS = ()
+
 ############# ModuleStore Configuration ##########
 
 MODULESTORE_BRANCH = 'published-only'
@@ -2643,6 +2646,10 @@ CHECKPOINT_PATTERN = r'(?P<checkpoint_name>[^/]+)'
 # this setting.
 FIELD_OVERRIDE_PROVIDERS = ()
 
+# Modulestore-level field override providers. These field override providers don't
+# require student context.
+MODULESTORE_FIELD_OVERRIDE_PROVIDERS = ()
+
 # PROFILE IMAGE CONFIG
 # WARNING: Certain django storage backends do not support atomic
 # file overwrites (including the default, OverwriteStorage) - instead