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Fixed #12734. Deferred fields will now be properly converted to python when accessed. Thanks, Alex Gaynor. 

git-svn-id: http://code.djangoproject.com/svn/django/trunk@12579 bcc190cf-cafb-0310-a4f2-bffc1f526a37
This commit is contained in:
Joseph Kocherhans 2010-02-24 19:06:59 +00:00
parent 16fe73d918
commit ff963358d7
5 changed files with 117 additions and 49 deletions
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20
django/db/models/query_utils.py
View File

@ -183,11 +183,29 @@ class DeferredAttribute(object):
Retrieves and caches the value from the datastore on the first lookup.
Returns the cached value.
"""
from django.db.models.fields import FieldDoesNotExist
assert instance is not None
cls = self.model_ref()
data = instance.__dict__
if data.get(self.field_name, self) is self:
data[self.field_name] = cls._base_manager.filter(pk=instance.pk).values_list(self.field_name, flat=True).using(instance._state.db).get()
# self.field_name is the attname of the field, but only() takes the
# actual name, so we need to translate it here.
try:
cls._meta.get_field_by_name(self.field_name)
name = self.field_name
except FieldDoesNotExist:
name = [f.name for f in cls._meta.fields
if f.attname == self.field_name][0]
# We use only() instead of values() here because we want the
# various data coersion methods (to_python(), etc.) to be called
# here.
val = getattr(
cls._base_manager.filter(pk=instance.pk).only(name).using(
instance._state.db).get(),
self.field_name
)
data[self.field_name] = val
return data[self.field_name]
def __set__(self, instance, value):

71
tests/modeltests/field_subclassing/fields.py Normal file
View File

@ -0,0 +1,71 @@
from django.core.exceptions import FieldError
from django.db import models
from django.utils import simplejson as json
from django.utils.encoding import force_unicode
class Small(object):
"""
A simple class to show that non-trivial Python objects can be used as
attributes.
"""
def __init__(self, first, second):
self.first, self.second = first, second
def __unicode__(self):
return u'%s%s' % (force_unicode(self.first), force_unicode(self.second))
def __str__(self):
return unicode(self).encode('utf-8')
class SmallField(models.Field):
"""
Turns the "Small" class into a Django field. Because of the similarities
with normal character fields and the fact that Small.__unicode__ does
something sensible, we don't need to implement a lot here.
"""
__metaclass__ = models.SubfieldBase
def __init__(self, *args, **kwargs):
kwargs['max_length'] = 2
super(SmallField, self).__init__(*args, **kwargs)
def get_internal_type(self):
return 'CharField'
def to_python(self, value):
if isinstance(value, Small):
return value
return Small(value[0], value[1])
def get_db_prep_save(self, value):
return unicode(value)
def get_db_prep_lookup(self, lookup_type, value):
if lookup_type == 'exact':
return force_unicode(value)
if lookup_type == 'in':
return [force_unicode(v) for v in value]
if lookup_type == 'isnull':
return []
raise FieldError('Invalid lookup type: %r' % lookup_type)
class JSONField(models.TextField):
__metaclass__ = models.SubfieldBase
description = ("JSONField automatically serializes and desializes values to "
"and from JSON.")
def to_python(self, value):
if not value:
return None
if isinstance(value, basestring):
value = json.loads(value)
return value
def get_db_prep_save(self, value):
if value is None:
return None
return json.dumps(value)

51
tests/modeltests/field_subclassing/models.py
View File

@ -2,56 +2,12 @@
Tests for field subclassing.
"""
from django.core import serializers
from django.db import models
from django.utils.encoding import force_unicode
from django.core import serializers
from django.core.exceptions import FieldError
class Small(object):
"""
A simple class to show that non-trivial Python objects can be used as
attributes.
"""
def __init__(self, first, second):
self.first, self.second = first, second
from fields import Small, SmallField, JSONField
def __unicode__(self):
return u'%s%s' % (force_unicode(self.first), force_unicode(self.second))
def __str__(self):
return unicode(self).encode('utf-8')
class SmallField(models.Field):
"""
Turns the "Small" class into a Django field. Because of the similarities
with normal character fields and the fact that Small.__unicode__ does
something sensible, we don't need to implement a lot here.
"""
__metaclass__ = models.SubfieldBase
def __init__(self, *args, **kwargs):
kwargs['max_length'] = 2
super(SmallField, self).__init__(*args, **kwargs)
def get_internal_type(self):
return 'CharField'
def to_python(self, value):
if isinstance(value, Small):
return value
return Small(value[0], value[1])
def get_db_prep_save(self, value):
return unicode(value)
def get_db_prep_lookup(self, lookup_type, value):
if lookup_type == 'exact':
return force_unicode(value)
if lookup_type == 'in':
return [force_unicode(v) for v in value]
if lookup_type == 'isnull':
return []
raise FieldError('Invalid lookup type: %r' % lookup_type)
class MyModel(models.Model):
name = models.CharField(max_length=10)
@ -60,6 +16,9 @@ class MyModel(models.Model):
def __unicode__(self):
return force_unicode(self.name)
class DataModel(models.Model):
data = JSONField()
__test__ = {'API_TESTS': ur"""
# Creating a model with custom fields is done as per normal.
>>> s = Small(1, 2)

21
tests/modeltests/field_subclassing/tests.py Normal file
View File

@ -0,0 +1,21 @@
from django.test import TestCase
from models import DataModel
class CustomField(TestCase):
def test_defer(self):
d = DataModel.objects.create(data=[1, 2, 3])
self.assertTrue(isinstance(d.data, list))
d = DataModel.objects.get(pk=d.pk)
self.assertTrue(isinstance(d.data, list))
self.assertEqual(d.data, [1, 2, 3])
d = DataModel.objects.defer("data").get(pk=d.pk)
d.save()
d = DataModel.objects.get(pk=d.pk)
self.assertTrue(isinstance(d.data, list))
self.assertEqual(d.data, [1, 2, 3])

3
tests/regressiontests/defer_regress/models.py
View File

@ -142,8 +142,7 @@ False
[<class 'regressiontests.defer_regress.models.Child'>, <class 'regressiontests.defer_regress.models.Item'>, <class 'regressiontests.defer_regress.models.Leaf'>, <class 'regressiontests.defer_regress.models.RelatedItem'>, <class 'regressiontests.defer_regress.models.ResolveThis'>]
>>> sorted(get_models(models.get_app('defer_regress'), include_deferred=True), key=lambda obj: obj._meta.object_name)
[<class 'regressiontests.defer_regress.models.Child'>, <class 'regressiontests.defer_regress.models.Item'>, <class 'regressiontests.defer_regress.models.Item_Deferred_name'>, <class 'regressiontests.defer_regress.models.Item_Deferred_name_other_value_text'>, <class 'regressiontests.defer_regress.models.Item_Deferred_other_value_text_value'>, <class 'regressiontests.defer_regress.models.Item_Deferred_text_value'>, <class 'regressiontests.defer_regress.models.Leaf'>, <class 'regressiontests.defer_regress.models.Leaf_Deferred_name_value'>, <class 'regressiontests.defer_regress.models.Leaf_Deferred_second_child_value'>, <class 'regressiontests.defer_regress.models.Leaf_Deferred_value'>, <class 'regressiontests.defer_regress.models.RelatedItem'>, <class 'regressiontests.defer_regress.models.RelatedItem_Deferred_item_id'>, <class 'regressiontests.defer_regress.models.ResolveThis'>, <class 'regressiontests.defer_regress.models.ResolveThis_Deferred_num'>]
[<class 'regressiontests.defer_regress.models.Child'>, <class 'regressiontests.defer_regress.models.Item'>, <class 'regressiontests.defer_regress.models.Item_Deferred_name'>, <class 'regressiontests.defer_regress.models.Item_Deferred_name_other_value_text'>, <class 'regressiontests.defer_regress.models.Item_Deferred_name_other_value_value'>, <class 'regressiontests.defer_regress.models.Item_Deferred_other_value_text_value'>, <class 'regressiontests.defer_regress.models.Item_Deferred_text_value'>, <class 'regressiontests.defer_regress.models.Leaf'>, <class 'regressiontests.defer_regress.models.Leaf_Deferred_child_id_second_child_id_value'>, <class 'regressiontests.defer_regress.models.Leaf_Deferred_name_value'>, <class 'regressiontests.defer_regress.models.Leaf_Deferred_second_child_value'>, <class 'regressiontests.defer_regress.models.Leaf_Deferred_value'>, <class 'regressiontests.defer_regress.models.RelatedItem'>, <class 'regressiontests.defer_regress.models.RelatedItem_Deferred_'>, <class 'regressiontests.defer_regress.models.RelatedItem_Deferred_item_id'>, <class 'regressiontests.defer_regress.models.ResolveThis'>, <class 'regressiontests.defer_regress.models.ResolveThis_Deferred_num'>]
"""
}