Use keys as strings.

notesapi/v1/models.py

 import json
 from django.db import models
 from django.core.exceptions import ValidationError
-from opaque_keys.edx.keys import CourseKey, UsageKey
-from opaque_keys.edx.locations import BlockUsageLocator, CourseLocator
-
-
-def _strip_object(key):
-    """
-    Strips branch and version info if the given key supports those attributes.
-    """
-    if hasattr(key, 'version_agnostic') and hasattr(key, 'for_branch'):
-        return key.for_branch(None).version_agnostic()
-    else:
-        return key
-
-
-def _strip_value(value, lookup='exact'):
-    """
-    Helper function to remove the branch and version information from the given value,
-    which could be a single object or a list.
-    """
-    if lookup == 'in':
-        stripped_value = [_strip_object(el) for el in value]
-    else:
-        stripped_value = _strip_object(value)
-    return stripped_value
-
-
-class OpaqueKeyField(models.CharField):
-    """
-    A django field for storing OpaqueKeys.
-
-    The baseclass will return the value from the database as a string, rather than an instance
-    of an OpaqueKey, leaving the application to determine which key subtype to parse the string
-    as.
-
-    Subclasses must specify a KEY_CLASS attribute, in which case the field will use :meth:`from_string`
-    to parse the key string, and will return an instance of KEY_CLASS.
-    """
-    description = "An OpaqueKey object, saved to the DB in the form of a string."
-
-    __metaclass__ = models.SubfieldBase
-
-    Empty = object()
-    KEY_CLASS = None
-
-    def __init__(self, *args, **kwargs):
-        if self.KEY_CLASS is None:
-            raise ValueError('Must specify KEY_CLASS in OpaqueKeyField subclasses')
-
-        super(OpaqueKeyField, self).__init__(*args, **kwargs)
-
-    def to_python(self, value):
-        if value is self.Empty or value is None:
-            return None
-
-        assert isinstance(value, (basestring, self.KEY_CLASS))
-        if value == '':
-            # handle empty string for models being created w/o fields populated
-            return None
-
-        if isinstance(value, basestring):
-            return self.KEY_CLASS.from_string(value)
-        else:
-            return value
-
-    def get_prep_lookup(self, lookup, value):
-        if lookup == 'isnull':
-            raise TypeError('Use {0}.Empty rather than None to query for a missing {0}'.format(self.__class__.__name__))
-
-        return super(OpaqueKeyField, self).get_prep_lookup(
-            lookup,
-            # strip key before comparing
-            _strip_value(value, lookup)
-        )
-
-    def get_prep_value(self, value):
-        if value is self.Empty or value is None:
-            return ''  # CharFields should use '' as their empty value, rather than None
-
-        assert isinstance(value, self.KEY_CLASS)
-        return unicode(_strip_value(value))
-
-    def validate(self, value, model_instance):
-        """Validate Empty values, otherwise defer to the parent"""
-        # raise validation error if the use of this field says it can't be blank but it is
-        if not self.blank and value is self.Empty:
-            raise ValidationError(self.error_messages['blank'])
-        else:
-            return super(OpaqueKeyField, self).validate(value, model_instance)
-
-    def run_validators(self, value):
-        """Validate Empty values, otherwise defer to the parent"""
-        if value is self.Empty:
-            return
-
-        return super(OpaqueKeyField, self).run_validators(value)
-
-
-class CourseKeyField(OpaqueKeyField):
-    """
-    A django Field that stores a CourseKey object as a string.
-    """
-    description = "A CourseKey object, saved to the DB in the form of a string"
-    KEY_CLASS = CourseKey
-
-
-class UsageKeyField(OpaqueKeyField):
-    """
-    A django Field that stores a UsageKey object as a string.
-    """
-    description = "A Location object, saved to the DB in the form of a string"
-    KEY_CLASS = UsageKey
 
 
 class Note(models.Model):
     user_id = models.CharField(max_length=255)
-    course_id = CourseKeyField(max_length=255)
-    usage_id = UsageKeyField(max_length=255)
+    course_id = models.CharField(max_length=255)
+    usage_id = models.CharField(max_length=255)
     text = models.TextField(default="")
     quote = models.TextField(default="")
     range_start = models.CharField(max_length=2048)
@@ -142,8 +31,8 @@ class Note(models.Model):
         self.quote = note.get('quote', '')
 
         try:
-            self.course_id = CourseLocator.from_string(note['course_id'])
-            self.usage_id = BlockUsageLocator.from_string(note['usage_id'])
+            self.course_id = note['course_id']
+            self.usage_id = note['usage_id']
             self.user_id = note['user']
         except KeyError as error:
             raise ValidationError('Note must have a course_id and usage_id and user_id.')
@@ -167,8 +56,8 @@ class Note(models.Model):
         return {
             'id': self.pk,
             'user': self.user_id,
-            'course_id': self.course_id.html_id(),
-            'usage_id': self.usage_id.to_deprecated_string(),
+            'course_id': self.course_id,
+            'usage_id': self.usage_id,
             'text': self.text,
             'quote': self.quote,
             'ranges': [{