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Make a generic django field for storing OpaqueKey classes

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This commit is contained in:
Calen Pennington
2014-12-02 13:54:51 -05:00
parent 0bce5569e2
commit ccbff2dafc
1 changed files with 43 additions and 58 deletions
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101
common/djangoapps/xmodule_django/models.py
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@@ -1,3 +1,5 @@
import warnings
from django.db import models
from django.core.exceptions import ValidationError
from opaque_keys.edx.locations import SlashSeparatedCourseKey, Location
@@ -5,8 +7,6 @@ from opaque_keys.edx.keys import CourseKey, UsageKey
from opaque_keys.edx.locator import Locator
from south.modelsinspector import add_introspection_rules
add_introspection_rules([], ["^xmodule_django\.models\.CourseKeyField"])
add_introspection_rules([], ["^xmodule_django\.models\.LocationKeyField"])
class NoneToEmptyManager(models.Manager):
@@ -67,32 +67,50 @@ def _strip_value(value, lookup='exact'):
return stripped_value
class CourseKeyField(models.CharField):
description = "A CourseKey object, saved to the DB in the form of a string"
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, CourseKey))
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 CourseKey.from_string(value)
return self.KEY_CLASS.from_string(value)
else:
return value
def get_prep_lookup(self, lookup, value):
if lookup == 'isnull':
raise TypeError('Use CourseKeyField.Empty rather than None to query for a missing CourseKeyField')
raise TypeError('Use {0}.Empty rather than None to query for a missing {0}'.format(self.__class__.__name__))
return super(CourseKeyField, self).get_prep_lookup(
return super(OpaqueKeyField, self).get_prep_lookup(
lookup,
# strip key before comparing
_strip_value(value, lookup)
@@ -102,7 +120,7 @@ class CourseKeyField(models.CharField):
if value is self.Empty or value is None:
return '' # CharFields should use '' as their empty value, rather than None
assert isinstance(value, CourseKey)
assert isinstance(value, self.KEY_CLASS)
return unicode(_strip_value(value))
def validate(self, value, model_instance):
@@ -111,66 +129,33 @@ class CourseKeyField(models.CharField):
if not self.blank and value is self.Empty:
raise ValidationError(self.error_messages['blank'])
else:
return super(CourseKeyField, self).validate(value, model_instance)
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(CourseKeyField, self).run_validators(value)
return super(OpaqueKeyField, self).run_validators(value)
class LocationKeyField(models.CharField):
class CourseKeyField(OpaqueKeyField):
description = "A CourseKey object, saved to the DB in the form of a string"
KEY_CLASS = CourseKey
class UsageKeyField(OpaqueKeyField):
description = "A Location object, saved to the DB in the form of a string"
KEY_CLASS = UsageKey
__metaclass__ = models.SubfieldBase
Empty = object()
class LocationKeyField(UsageKeyField):
def __init__(self, *args, **kwargs):
warnings.warn("LocationKeyField is deprecated. Please use UsageKeyField instead.", stacklevel=2)
super(LocationKeyField, self).__init__(*args, **kwargs)
def to_python(self, value):
if value is self.Empty or value is None:
return value
assert isinstance(value, (basestring, UsageKey))
if value == '':
return None
if isinstance(value, basestring):
return Location.from_deprecated_string(value)
else:
return value
def get_prep_lookup(self, lookup, value):
if lookup == 'isnull':
raise TypeError('Use LocationKeyField.Empty rather than None to query for a missing LocationKeyField')
# remove version and branch info before comparing keys
return super(LocationKeyField, self).get_prep_lookup(
lookup,
# strip key before comparing
_strip_value(value, lookup)
)
def get_prep_value(self, value):
if value is self.Empty:
return ''
assert isinstance(value, UsageKey)
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(LocationKeyField, 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(LocationKeyField, self).run_validators(value)
add_introspection_rules([], ["^xmodule_django\.models\.CourseKeyField"])
add_introspection_rules([], ["^xmodule_django\.models\.LocationKeyField"])
add_introspection_rules([], ["^xmodule_django\.models\.UsageKeyField"])