Create helper function to remove duplicate code

This repetitive code is especially pronounced in Stanford's fork, where
we have extended the About page to include several additional fields.

This pays down some technical debt by refactoring into a shared helper.

cms/djangoapps/models/settings/course_details.py

@@ -11,6 +11,16 @@ from models.settings import course_grading
 from xmodule.fields import Date
 from xmodule.modulestore.django import modulestore
 
+# This list represents the attribute keys for a course's 'about' info.
+# Note: The 'video' attribute is intentionally excluded as it must be
+# handled separately; its value maps to an alternate key name.
+ABOUT_ATTRIBUTES = [
+    'syllabus',
+    'short_description',
+    'overview',
+    'effort',
+]
+
 
 class CourseDetails(object):
     def __init__(self, org, course_id, run):
@@ -31,6 +41,18 @@ class CourseDetails(object):
         self.course_image_asset_path = ""  # URL of the course image
 
     @classmethod
+    def _fetch_about_attribute(cls, course_key, attribute):
+        """
+        Retrieve an attribute from a course's "about" info
+        """
+        usage_key = course_key.make_usage_key('about', attribute)
+        try:
+            value = modulestore().get_item(usage_key).data
+        except ItemNotFoundError:
+            value = None
+        return value
+
+    @classmethod
     def fetch(cls, course_key):
         """
         Fetch the course details for the given course from persistence and return a CourseDetails model.
@@ -45,36 +67,14 @@ class CourseDetails(object):
         course_details.course_image_name = descriptor.course_image
         course_details.course_image_asset_path = course_image_url(descriptor)
 
-        temploc = course_key.make_usage_key('about', 'syllabus')
-        try:
-            course_details.syllabus = modulestore().get_item(temploc).data
-        except ItemNotFoundError:
-            pass
-
-        temploc = course_key.make_usage_key('about', 'short_description')
-        try:
-            course_details.short_description = modulestore().get_item(temploc).data
-        except ItemNotFoundError:
-            pass
-
-        temploc = course_key.make_usage_key('about', 'overview')
-        try:
-            course_details.overview = modulestore().get_item(temploc).data
-        except ItemNotFoundError:
-            pass
+        for attribute in ABOUT_ATTRIBUTES:
+            value = cls._fetch_about_attribute(course_key, attribute)
+            if value is not None:
+                setattr(course_details, attribute, value)
 
-        temploc = course_key.make_usage_key('about', 'effort')
-        try:
-            course_details.effort = modulestore().get_item(temploc).data
-        except ItemNotFoundError:
-            pass
-
-        temploc = course_key.make_usage_key('about', 'video')
-        try:
-            raw_video = modulestore().get_item(temploc).data
+        raw_video = cls._fetch_about_attribute(course_key, 'video')
+        if raw_video:
             course_details.intro_video = CourseDetails.parse_video_tag(raw_video)
-        except ItemNotFoundError:
-            pass
 
         return course_details
 
@@ -160,8 +160,8 @@ class CourseDetails(object):
 
         # NOTE: below auto writes to the db w/o verifying that any of the fields actually changed
         # to make faster, could compare against db or could have client send over a list of which fields changed.
-        for about_type in ['syllabus', 'overview', 'effort', 'short_description']:
-            cls.update_about_item(course_key, about_type, jsondict[about_type], descriptor, user)
+        for attribute in ABOUT_ATTRIBUTES:
+            cls.update_about_item(course_key, attribute, jsondict[attribute], descriptor, user)
 
         recomposed_video_tag = CourseDetails.recompose_video_tag(jsondict['intro_video'])
         cls.update_about_item(course_key, 'video', recomposed_video_tag, descriptor, user)