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
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
|
from __future__ import unicode_literals
from django.db.models.query_utils import InvalidQuery
from django.test import TestCase
from .models import (
BigChild, Child, ChildProxy, Primary, RefreshPrimaryProxy, Secondary,
)
class AssertionMixin(object):
def assert_delayed(self, obj, num):
"""
Instances with deferred fields look the same as normal instances when
we examine attribute values. Therefore, this method returns the number
of deferred fields on returned instances.
"""
count = len(obj.get_deferred_fields())
self.assertEqual(count, num)
class DeferTests(AssertionMixin, TestCase):
@classmethod
def setUpTestData(cls):
cls.s1 = Secondary.objects.create(first="x1", second="y1")
cls.p1 = Primary.objects.create(name="p1", value="xx", related=cls.s1)
def test_defer(self):
qs = Primary.objects.all()
self.assert_delayed(qs.defer("name")[0], 1)
self.assert_delayed(qs.defer("name").get(pk=self.p1.pk), 1)
self.assert_delayed(qs.defer("related__first")[0], 0)
self.assert_delayed(qs.defer("name").defer("value")[0], 2)
def test_only(self):
qs = Primary.objects.all()
self.assert_delayed(qs.only("name")[0], 2)
self.assert_delayed(qs.only("name").get(pk=self.p1.pk), 2)
self.assert_delayed(qs.only("name").only("value")[0], 2)
self.assert_delayed(qs.only("related__first")[0], 2)
# Using 'pk' with only() should result in 3 deferred fields, namely all
# of them except the model's primary key see #15494
self.assert_delayed(qs.only("pk")[0], 3)
# You can use 'pk' with reverse foreign key lookups.
# The related_id is alawys set even if it's not fetched from the DB,
# so pk and related_id are not deferred.
self.assert_delayed(self.s1.primary_set.all().only('pk')[0], 2)
def test_defer_only_chaining(self):
qs = Primary.objects.all()
self.assert_delayed(qs.only("name", "value").defer("name")[0], 2)
self.assert_delayed(qs.defer("name").only("value", "name")[0], 2)
self.assert_delayed(qs.defer("name").only("value")[0], 2)
self.assert_delayed(qs.only("name").defer("value")[0], 2)
def test_defer_on_an_already_deferred_field(self):
qs = Primary.objects.all()
self.assert_delayed(qs.defer("name")[0], 1)
self.assert_delayed(qs.defer("name").defer("name")[0], 1)
def test_defer_none_to_clear_deferred_set(self):
qs = Primary.objects.all()
self.assert_delayed(qs.defer("name", "value")[0], 2)
self.assert_delayed(qs.defer(None)[0], 0)
self.assert_delayed(qs.only("name").defer(None)[0], 0)
def test_only_none_raises_error(self):
msg = 'Cannot pass None as an argument to only().'
with self.assertRaisesMessage(TypeError, msg):
Primary.objects.only(None)
def test_defer_extra(self):
qs = Primary.objects.all()
self.assert_delayed(qs.defer("name").extra(select={"a": 1})[0], 1)
self.assert_delayed(qs.extra(select={"a": 1}).defer("name")[0], 1)
def test_defer_values_does_not_defer(self):
# User values() won't defer anything (you get the full list of
# dictionaries back), but it still works.
self.assertEqual(Primary.objects.defer("name").values()[0], {
"id": self.p1.id,
"name": "p1",
"value": "xx",
"related_id": self.s1.id,
})
def test_only_values_does_not_defer(self):
self.assertEqual(Primary.objects.only("name").values()[0], {
"id": self.p1.id,
"name": "p1",
"value": "xx",
"related_id": self.s1.id,
})
def test_get(self):
# Using defer() and only() with get() is also valid.
qs = Primary.objects.all()
self.assert_delayed(qs.defer("name").get(pk=self.p1.pk), 1)
self.assert_delayed(qs.only("name").get(pk=self.p1.pk), 2)
def test_defer_with_select_related(self):
obj = Primary.objects.select_related().defer("related__first", "related__second")[0]
self.assert_delayed(obj.related, 2)
self.assert_delayed(obj, 0)
def test_only_with_select_related(self):
obj = Primary.objects.select_related().only("related__first")[0]
self.assert_delayed(obj, 2)
self.assert_delayed(obj.related, 1)
self.assertEqual(obj.related_id, self.s1.pk)
self.assertEqual(obj.name, "p1")
def test_defer_select_related_raises_invalid_query(self):
msg = (
'Field Primary.related cannot be both deferred and traversed '
'using select_related at the same time.'
)
with self.assertRaisesMessage(InvalidQuery, msg):
Primary.objects.defer("related").select_related("related")[0]
def test_only_select_related_raises_invalid_query(self):
msg = (
'Field Primary.related cannot be both deferred and traversed using '
'select_related at the same time.'
)
with self.assertRaisesMessage(InvalidQuery, msg):
Primary.objects.only("name").select_related("related")[0]
def test_defer_foreign_keys_are_deferred_and_not_traversed(self):
# select_related() overrides defer().
with self.assertNumQueries(1):
obj = Primary.objects.defer("related").select_related()[0]
self.assert_delayed(obj, 1)
self.assertEqual(obj.related.id, self.s1.pk)
def test_saving_object_with_deferred_field(self):
# Saving models with deferred fields is possible (but inefficient,
# since every field has to be retrieved first).
Primary.objects.create(name="p2", value="xy", related=self.s1)
obj = Primary.objects.defer("value").get(name="p2")
obj.name = "a new name"
obj.save()
self.assertQuerysetEqual(
Primary.objects.all(), [
"p1", "a new name",
],
lambda p: p.name,
ordered=False,
)
def test_defer_baseclass_when_subclass_has_no_added_fields(self):
# Regression for #10572 - A subclass with no extra fields can defer
# fields from the base class
Child.objects.create(name="c1", value="foo", related=self.s1)
# You can defer a field on a baseclass when the subclass has no fields
obj = Child.objects.defer("value").get(name="c1")
self.assert_delayed(obj, 1)
self.assertEqual(obj.name, "c1")
self.assertEqual(obj.value, "foo")
def test_only_baseclass_when_subclass_has_no_added_fields(self):
# You can retrieve a single column on a base class with no fields
Child.objects.create(name="c1", value="foo", related=self.s1)
obj = Child.objects.only("name").get(name="c1")
# on an inherited model, its PK is also fetched, hence '3' deferred fields.
self.assert_delayed(obj, 3)
self.assertEqual(obj.name, "c1")
self.assertEqual(obj.value, "foo")
class BigChildDeferTests(AssertionMixin, TestCase):
@classmethod
def setUpTestData(cls):
cls.s1 = Secondary.objects.create(first="x1", second="y1")
BigChild.objects.create(name="b1", value="foo", related=cls.s1, other="bar")
def test_defer_baseclass_when_subclass_has_added_field(self):
# You can defer a field on a baseclass
obj = BigChild.objects.defer("value").get(name="b1")
self.assert_delayed(obj, 1)
self.assertEqual(obj.name, "b1")
self.assertEqual(obj.value, "foo")
self.assertEqual(obj.other, "bar")
def test_defer_subclass(self):
# You can defer a field on a subclass
obj = BigChild.objects.defer("other").get(name="b1")
self.assert_delayed(obj, 1)
self.assertEqual(obj.name, "b1")
self.assertEqual(obj.value, "foo")
self.assertEqual(obj.other, "bar")
def test_defer_subclass_both(self):
# Deferring fields from both superclass and subclass works.
obj = BigChild.objects.defer("other", "value").get(name="b1")
self.assert_delayed(obj, 2)
def test_only_baseclass_when_subclass_has_added_field(self):
# You can retrieve a single field on a baseclass
obj = BigChild.objects.only("name").get(name="b1")
# when inherited model, its PK is also fetched, hence '4' deferred fields.
self.assert_delayed(obj, 4)
self.assertEqual(obj.name, "b1")
self.assertEqual(obj.value, "foo")
self.assertEqual(obj.other, "bar")
def test_only_sublcass(self):
# You can retrieve a single field on a subclass
obj = BigChild.objects.only("other").get(name="b1")
self.assert_delayed(obj, 4)
self.assertEqual(obj.name, "b1")
self.assertEqual(obj.value, "foo")
self.assertEqual(obj.other, "bar")
class TestDefer2(AssertionMixin, TestCase):
def test_defer_proxy(self):
"""
Ensure select_related together with only on a proxy model behaves
as expected. See #17876.
"""
related = Secondary.objects.create(first='x1', second='x2')
ChildProxy.objects.create(name='p1', value='xx', related=related)
children = ChildProxy.objects.all().select_related().only('id', 'name')
self.assertEqual(len(children), 1)
child = children[0]
self.assert_delayed(child, 2)
self.assertEqual(child.name, 'p1')
self.assertEqual(child.value, 'xx')
def test_defer_inheritance_pk_chaining(self):
"""
When an inherited model is fetched from the DB, its PK is also fetched.
When getting the PK of the parent model it is useful to use the already
fetched parent model PK if it happens to be available.
"""
s1 = Secondary.objects.create(first="x1", second="y1")
bc = BigChild.objects.create(name="b1", value="foo", related=s1,
other="bar")
bc_deferred = BigChild.objects.only('name').get(pk=bc.pk)
with self.assertNumQueries(0):
bc_deferred.id
self.assertEqual(bc_deferred.pk, bc_deferred.id)
def test_eq(self):
s1 = Secondary.objects.create(first="x1", second="y1")
s1_defer = Secondary.objects.only('pk').get(pk=s1.pk)
self.assertEqual(s1, s1_defer)
self.assertEqual(s1_defer, s1)
def test_refresh_not_loading_deferred_fields(self):
s = Secondary.objects.create()
rf = Primary.objects.create(name='foo', value='bar', related=s)
rf2 = Primary.objects.only('related', 'value').get()
rf.name = 'new foo'
rf.value = 'new bar'
rf.save()
with self.assertNumQueries(1):
rf2.refresh_from_db()
self.assertEqual(rf2.value, 'new bar')
with self.assertNumQueries(1):
self.assertEqual(rf2.name, 'new foo')
def test_custom_refresh_on_deferred_loading(self):
s = Secondary.objects.create()
rf = RefreshPrimaryProxy.objects.create(name='foo', value='bar', related=s)
rf2 = RefreshPrimaryProxy.objects.only('related').get()
rf.name = 'new foo'
rf.value = 'new bar'
rf.save()
with self.assertNumQueries(1):
# Customized refresh_from_db() reloads all deferred fields on
# access of any of them.
self.assertEqual(rf2.name, 'new foo')
self.assertEqual(rf2.value, 'new bar')
|
