Refactor 'value' models into shared abstract model

course_discovery/apps/course_metadata/migrations/0002_auto_20160404_1626.py

+# -*- coding: utf-8 -*-
+from __future__ import unicode_literals
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('course_metadata', '0001_initial'),
+    ]
+
+    operations = [
+        migrations.AlterModelOptions(
+            name='expectedlearningitem',
+            options={},
+        ),
+        migrations.AlterModelOptions(
+            name='syllabusitem',
+            options={},
+        ),
+    ]

course_discovery/apps/course_metadata/models.py

@@ -23,6 +23,17 @@ class AbstractNamedModel(TimeStampedModel):
         abstract = True
 
 
+class AbstractValueModel(TimeStampedModel):
+    """ Abstract base class for models with only a value field. """
+    value = models.CharField(max_length=255)
+
+    def __str__(self):
+        return self.value
+
+    class Meta(object):
+        abstract = True
+
+
 class AbstractMediaModel(TimeStampedModel):
     """ Abstract base class for media-related (e.g. image, video) models. """
     src = models.URLField(max_length=255, unique=True)
@@ -58,18 +69,14 @@ class Prerequisite(AbstractNamedModel):
     pass
 
 
-class ExpectedLearningItem(TimeStampedModel):
+class ExpectedLearningItem(AbstractValueModel):
     """ ExpectedLearningItem model. """
-    value = models.CharField(max_length=255)
-
-    def __str__(self):
-        return self.value
+    pass
 
 
-class SyllabusItem(TimeStampedModel):
+class SyllabusItem(AbstractValueModel):
     """ SyllabusItem model. """
     parent = models.ForeignKey('self', blank=True, null=True, related_name='children')
-    value = models.CharField(max_length=255)
 
 
 class Organization(TimeStampedModel):

course_discovery/apps/course_metadata/tests/test_models.py

@@ -2,7 +2,7 @@ import ddt
 from django.test import TestCase
 
 from course_discovery.apps.course_metadata.models import(
-    AbstractNamedModel, AbstractMediaModel, CourseOrganization, ExpectedLearningItem
+    AbstractNamedModel, AbstractMediaModel, AbstractValueModel, CourseOrganization
 )
 from course_discovery.apps.course_metadata.tests import factories
 
@@ -124,12 +124,15 @@ class AbstractMediaModelTests(TestCase):
         self.assertEqual(str(instance), src)
 
 
-class ExpectedLearningItemTests(TestCase):
-    """ Tests for ExpectedLearningItem. """
+class AbstractValueModelTests(TestCase):
+    """ Tests for AbstractValueModel. """
 
     def test_str(self):
         """ Verify casting an instance to a string returns a string containing the value. """
 
-        value = 'Expected learnings'
-        instance = ExpectedLearningItem(value=value)
+        class TestAbstractValueModel(AbstractValueModel):
+            pass
+
+        value = 'abc'
+        instance = TestAbstractValueModel(value=value)
         self.assertEqual(str(instance), value)