1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
|
#!/usr/bin/python2.4
#
# Copyright 2008 Google Inc.
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
# distributed under the License is distributed on an "AS IS" BASIS,
# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
# See the License for the specific language governing permissions and
# limitations under the License.
import sys
import types
from google.appengine.ext import db
from django import VERSION
from django.core.exceptions import ObjectDoesNotExist
from django.db.models.fields import Field
from django.db.models.options import Options
from django.db.models.loading import register_models, get_model
class ModelManager(object):
"""Replacement for the default Django model manager."""
def __init__(self, owner):
self.owner = owner
def __getattr__(self, name):
"""Pass all attribute requests through to the real model"""
return getattr(self.owner, name)
class ModelOptions(object):
"""Replacement for the default Django options class.
This class sits at ._meta of each model. The primary information supplied by
this class that needs to be stubbed out is the list of fields on the model.
"""
def __init__(self, cls):
self.object_name = cls.__name__
self.module_name = self.object_name.lower()
model_module = sys.modules[cls.__module__]
self.app_label = model_module.__name__.split('.')[-2]
self.abstract = False
class pk:
"""Stub the primary key to always be 'key_name'"""
name = "key_name"
def __str__(self):
return "%s.%s" % (self.app_label, self.module_name)
@property
def many_to_many(self):
"""The datastore does not support many to many relationships."""
return []
class Relation(object):
def __init__(self, to):
self.field_name = "key_name"
def PropertyWrapper(prop):
"""Wrapper for db.Property to make it look like a Django model Property"""
if isinstance(prop, db.Reference):
prop.rel = Relation(prop.reference_class)
else:
prop.rel = None
prop.serialize = True
return prop
class PropertiedClassWithDjango(db.PropertiedClass):
"""Metaclass for the combined Django + App Engine model class.
This metaclass inherits from db.PropertiedClass in the appengine library.
This metaclass has two additional purposes:
1) Register each model class created with Django (the parent class will take
care of registering it with the appengine libraries).
2) Add the (minimum number) of attributes and methods to make Django believe
the class is a normal Django model.
The resulting classes are still not generally useful as Django classes and
are intended to be used by Django only in limited situations such as loading
and dumping fixtures.
"""
def __new__(cls, name, bases, attrs):
"""Creates a combined appengine and Django model.
The resulting model will be known to both the appengine libraries and
Django.
"""
if name == 'BaseModel':
# This metaclass only acts on subclasses of BaseModel.
return super(PropertiedClassWithDjango, cls).__new__(cls, name,
bases, attrs)
new_class = super(PropertiedClassWithDjango, cls).__new__(cls, name,
bases, attrs)
new_class._meta = ModelOptions(new_class)
new_class.objects = ModelManager(new_class)
new_class._default_manager = new_class.objects
new_class.DoesNotExist = types.ClassType('DoesNotExist',
(ObjectDoesNotExist,), {})
m = get_model(new_class._meta.app_label, name, False)
if m:
return m
register_models(new_class._meta.app_label, new_class)
return get_model(new_class._meta.app_label, name, False)
def __init__(cls, name, bases, attrs):
"""Initialises the list of Django properties.
This method takes care of wrapping the properties created by the superclass
so that they look like Django properties and installing them into the
._meta object of the class so that Django can find them at the appropriate
time.
"""
super(PropertiedClassWithDjango, cls).__init__(name, bases, attrs)
if name == 'BaseModel':
# This metaclass only acts on subclasses of BaseModel.
return
fields = [PropertyWrapper(p) for p in cls._properties.values()]
cls._meta.local_fields = fields
class BaseModel(db.Model):
"""Combined appengine and Django model.
All models used in the application should derive from this class.
"""
__metaclass__ = PropertiedClassWithDjango
def __eq__(self, other):
if not isinstance(other, self.__class__):
return False
return self._get_pk_val() == other._get_pk_val()
def __ne__(self, other):
return not self.__eq__(other)
def _get_pk_val(self):
"""Return the string representation of the model's key"""
return unicode(self.key())
def __repr__(self):
"""Create a string that can be used to construct an equivalent object.
e.g. eval(repr(obj)) == obj
"""
# First, creates a dictionary of property names and values. Note that
# property values, not property objects, has to be passed in to constructor.
def _MakeReprTuple(prop_name):
prop = getattr(self.__class__, prop_name)
return (prop_name, prop.get_value_for_datastore(self))
d = dict([_MakeReprTuple(prop_name) for prop_name in self.properties()])
return "%s(**%s)" % (self.__class__.__name__, repr(d))
class RegistrationTestModel(BaseModel):
"""Used to check registration with Django is working correctly.
Django 0.96 only recognises models defined within an applications models
module when get_models() is called so this definition must be here rather
than within the associated test (tests/model_test.py).
"""
pass
|
