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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_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 TypeError('Invalid lookup type: %r' % lookup_type)
class SmallerField(SmallField):
pass
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)
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