Provide access to the course_id directly on XModules/Descriptors

Fixes [BLD-456] and [LMS-1392], but making sure that we're always asking
XModules about their course_id (since the ModuleSystem has access to
that data).

common/lib/xmodule/xmodule/conditional_module.py

@@ -4,6 +4,7 @@ some xmodules by conditions.
 
 import json
 import logging
+from lazy import lazy
 from lxml import etree
 from pkg_resources import resource_string
 
@@ -97,10 +98,12 @@ class ConditionalModule(ConditionalFields, XModule):
                 return xml_value, attr_name
         raise Exception('Error in conditional module: unknown condition "%s"' % xml_attr)
 
-    def is_condition_satisfied(self):
-        self.required_modules = [self.system.get_module(descriptor) for
-                                 descriptor in self.descriptor.get_required_module_descriptors()]
+    @lazy
+    def required_modules(self):
+        return [self.system.get_module(descriptor) for
+                descriptor in self.descriptor.get_required_module_descriptors()]
 
+    def is_condition_satisfied(self):
         xml_value, attr_name = self._get_condition()
 
         if xml_value and self.required_modules:

common/lib/xmodule/xmodule/lti_module.py

@@ -181,7 +181,7 @@ class LTIModule(LTIFields, XModule):
         ]
 
         # Obtains client_key and client_secret credentials from current course:
-        course_id = self.runtime.course_id
+        course_id = self.course_id
         course_location = CourseDescriptor.id_to_location(course_id)
         course = self.descriptor.runtime.modulestore.get_item(course_location)
         client_key = client_secret = ''

common/lib/xmodule/xmodule/peer_grading_module.py

@@ -519,7 +519,7 @@ class PeerGradingModule(PeerGradingFields, XModule):
         error_text = ""
         problem_list = []
         try:
-            problem_list_json = self.peer_gs.get_problem_list(self.system.course_id, self.system.anonymous_student_id)
+            problem_list_json = self.peer_gs.get_problem_list(self.course_id, self.system.anonymous_student_id)
             problem_list_dict = problem_list_json
             success = problem_list_dict['success']
             if 'error' in problem_list_dict:
@@ -569,7 +569,7 @@ class PeerGradingModule(PeerGradingFields, XModule):
 
         ajax_url = self.ajax_url
         html = self.system.render_template('peer_grading/peer_grading.html', {
-            'course_id': self.system.course_id,
+            'course_id': self.course_id,
             'ajax_url': ajax_url,
             'success': success,
             'problem_list': good_problem_list,
@@ -603,7 +603,7 @@ class PeerGradingModule(PeerGradingFields, XModule):
         html = self.system.render_template('peer_grading/peer_grading_problem.html', {
             'view_html': '',
             'problem_location': problem_location,
-            'course_id': self.system.course_id,
+            'course_id': self.course_id,
             'ajax_url': ajax_url,
             # Checked above
             'staff_access': False,

common/lib/xmodule/xmodule/x_module.py

@@ -133,6 +133,10 @@ class XModuleMixin(XBlockMixin):
         default=None
     )
 
+    @property
+    def course_id(self):
+        return self.runtime.course_id
+
     @property
     def id(self):
         return self.location.url()
@@ -743,6 +747,7 @@ class XModuleDescriptor(XModuleMixin, HTMLSnippet, ResourceTemplates, XBlock):
                 self.xmodule_runtime.xmodule_instance = descriptor._xmodule  # pylint: disable=protected-access
         return self.xmodule_runtime.xmodule_instance
 
+    course_id = module_attr('course_id')
     displayable_items = module_attr('displayable_items')
     get_display_items = module_attr('get_display_items')
     get_icon_class = module_attr('get_icon_class')

lms/templates/conditional_module.html

 <%
-from django.core.urlresolvers import reverse
 
-# course_id = module.location.course_id
-def get_course_id(module):
-    return module.location.org +'/' + module.location.course +'/' + \
-                module.system.ajax_url.split('/')[4]
+from django.core.urlresolvers import reverse
 
 def _message(reqm, message):
     return message.format(link="<a href={url}>{url_name}</a>".format(
-        url = reverse('jump_to', kwargs=dict(course_id=get_course_id(reqm),
+        url = reverse('jump_to', kwargs=dict(course_id=reqm.course_id,
                         location=reqm.location.url())),
         url_name = reqm.display_name_with_default))
 %>