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import pickle
from unittest import SkipTest
from django.db.models import IntegerField, TextField
from django.db.models.expressions import (
Case,
Exists,
ExpressionWrapper,
F,
OuterRef,
Q,
Value,
When,
)
from django.db.models.functions import Concat
from django.db.utils import DatabaseError
from django.test import TestCase
from django_cte import With
from .models import KeyPair, Region
int_field = IntegerField()
text_field = TextField()
class TestRecursiveCTE(TestCase):
def test_recursive_cte_query(self):
def make_regions_cte(cte):
return Region.objects.filter(
# non-recursive: get root nodes
parent__isnull=True
).values(
"name",
path=F("name"),
depth=Value(0, output_field=int_field),
).union(
# recursive union: get descendants
cte.join(Region, parent=cte.col.name).values(
"name",
path=Concat(
cte.col.path, Value(" / "), F("name"),
output_field=text_field,
),
depth=cte.col.depth + Value(1, output_field=int_field),
),
all=True,
)
cte = With.recursive(make_regions_cte)
regions = (
cte.join(Region, name=cte.col.name)
.with_cte(cte)
.annotate(
path=cte.col.path,
depth=cte.col.depth,
)
.filter(depth=2)
.order_by("path")
)
print(regions.query)
data = [(r.name, r.path, r.depth) for r in regions]
self.assertEqual(data, [
('moon', 'sun / earth / moon', 2),
('deimos', 'sun / mars / deimos', 2),
('phobos', 'sun / mars / phobos', 2),
])
def test_recursive_cte_reference_in_condition(self):
def make_regions_cte(cte):
return Region.objects.filter(
parent__isnull=True
).values(
"name",
path=F("name"),
depth=Value(0, output_field=int_field),
is_planet=Value(0, output_field=int_field),
).union(
cte.join(
Region, parent=cte.col.name
).annotate(
# annotations for filter and CASE/WHEN conditions
parent_name=ExpressionWrapper(
cte.col.name,
output_field=text_field,
),
parent_depth=ExpressionWrapper(
cte.col.depth,
output_field=int_field,
),
).filter(
~Q(parent_name="mars"),
).values(
"name",
path=Concat(
cte.col.path, Value("\x01"), F("name"),
output_field=text_field,
),
depth=cte.col.depth + Value(1, output_field=int_field),
is_planet=Case(
When(parent_depth=0, then=Value(1)),
default=Value(0),
output_field=int_field,
),
),
all=True,
)
cte = With.recursive(make_regions_cte)
regions = cte.join(Region, name=cte.col.name).with_cte(cte).annotate(
path=cte.col.path,
depth=cte.col.depth,
is_planet=cte.col.is_planet,
).order_by("path")
data = [(r.path.split("\x01"), r.is_planet) for r in regions]
print(data)
self.assertEqual(data, [
(["bernard's star"], 0),
(['proxima centauri'], 0),
(['proxima centauri', 'proxima centauri b'], 1),
(['sun'], 0),
(['sun', 'earth'], 1),
(['sun', 'earth', 'moon'], 0),
(['sun', 'mars'], 1), # mars moons excluded: parent_name != 'mars'
(['sun', 'mercury'], 1),
(['sun', 'venus'], 1),
])
def test_recursive_cte_with_empty_union_part(self):
def make_regions_cte(cte):
return Region.objects.none().union(
cte.join(Region, parent=cte.col.name),
all=True,
)
cte = With.recursive(make_regions_cte)
regions = cte.join(Region, name=cte.col.name).with_cte(cte)
print(regions.query)
try:
self.assertEqual(regions.count(), 0)
except DatabaseError:
raise SkipTest(
"Expected failure: QuerySet omits `EmptyQuerySet` from "
"UNION queries resulting in invalid CTE SQL"
)
# -- recursive query "cte" does not have the form
# -- non-recursive-term UNION [ALL] recursive-term
# WITH RECURSIVE cte AS (
# SELECT "tests_region"."name", "tests_region"."parent_id"
# FROM "tests_region", "cte"
# WHERE "tests_region"."parent_id" = ("cte"."name")
# )
# SELECT COUNT(*)
# FROM "tests_region", "cte"
# WHERE "tests_region"."name" = ("cte"."name")
def test_circular_ref_error(self):
def make_bad_cte(cte):
# NOTE: not a valid recursive CTE query
return cte.join(Region, parent=cte.col.name).values(
depth=cte.col.depth + 1,
)
cte = With.recursive(make_bad_cte)
regions = cte.join(Region, name=cte.col.name).with_cte(cte)
with self.assertRaises(ValueError) as context:
print(regions.query)
self.assertIn("Circular reference:", str(context.exception))
def test_attname_should_not_mask_col_name(self):
def make_regions_cte(cte):
return Region.objects.filter(
name="moon"
).values(
"name",
"parent_id",
).union(
cte.join(Region, name=cte.col.parent_id).values(
"name",
"parent_id",
),
all=True,
)
cte = With.recursive(make_regions_cte)
regions = (
Region.objects.all()
.with_cte(cte)
.annotate(_ex=Exists(
cte.queryset()
.values(value=Value("1", output_field=int_field))
.filter(name=OuterRef("name"))
))
.filter(_ex=True)
.order_by("name")
)
print(regions.query)
data = [r.name for r in regions]
self.assertEqual(data, ['earth', 'moon', 'sun'])
def test_pickle_recursive_cte_queryset(self):
def make_regions_cte(cte):
return Region.objects.filter(
parent__isnull=True
).annotate(
depth=Value(0, output_field=int_field),
).union(
cte.join(Region, parent=cte.col.name).annotate(
depth=cte.col.depth + Value(1, output_field=int_field),
),
all=True,
)
cte = With.recursive(make_regions_cte)
regions = cte.queryset().with_cte(cte).filter(depth=2).order_by("name")
pickled_qs = pickle.loads(pickle.dumps(regions))
data = [(r.name, r.depth) for r in pickled_qs]
self.assertEqual(data, [(r.name, r.depth) for r in regions])
self.assertEqual(data, [('deimos', 2), ('moon', 2), ('phobos', 2)])
def test_alias_change_in_annotation(self):
def make_regions_cte(cte):
return Region.objects.filter(
parent__name="sun",
).annotate(
value=F('name'),
).union(
cte.join(
Region.objects.all().annotate(
value=F('name'),
),
parent_id=cte.col.name,
),
all=True,
)
cte = With.recursive(make_regions_cte)
query = cte.queryset().with_cte(cte)
exclude_leaves = With(cte.queryset().filter(
parent__name='sun',
).annotate(
value=Concat(F('name'), F('name'))
), name='value_cte')
query = query.annotate(
_exclude_leaves=Exists(
exclude_leaves.queryset().filter(
name=OuterRef("name"),
value=OuterRef("value"),
)
)
).filter(_exclude_leaves=True).with_cte(exclude_leaves)
print(query.query)
# Nothing should be returned.
self.assertFalse(query)
def test_alias_as_subquery(self):
# This test covers CTEColumnRef.relabeled_clone
def make_regions_cte(cte):
return KeyPair.objects.filter(
parent__key="level 1",
).annotate(
rank=F('value'),
).union(
cte.join(
KeyPair.objects.all().order_by(),
parent_id=cte.col.id,
).annotate(
rank=F('value'),
),
all=True,
)
cte = With.recursive(make_regions_cte)
children = cte.queryset().with_cte(cte)
xdups = With(cte.queryset().filter(
parent__key="level 1",
).annotate(
rank=F('value')
).values('id', 'rank'), name='xdups')
children = children.annotate(
_exclude=Exists(
(
xdups.queryset().filter(
id=OuterRef("id"),
rank=OuterRef("rank"),
)
)
)
).filter(_exclude=True).with_cte(xdups)
print(children.query)
query = KeyPair.objects.filter(parent__in=children)
print(query.query)
print(children.query)
self.assertEqual(query.get().key, 'level 3')
# Tests the case in which children's query was modified since it was
# used in a subquery to define `query` above.
self.assertEqual(
list(c.key for c in children),
['level 2', 'level 2']
)
def test_materialized(self):
# This test covers MATERIALIZED option in SQL query
def make_regions_cte(cte):
return KeyPair.objects.all()
cte = With.recursive(make_regions_cte, materialized=True)
query = KeyPair.objects.with_cte(cte)
print(query.query)
self.assertTrue(
str(query.query).startswith('WITH RECURSIVE "cte" AS MATERIALIZED')
)
def test_recursive_self_queryset(self):
def make_regions_cte(cte):
return Region.objects.filter(
pk="earth"
).values("pk").union(
cte.join(Region, parent=cte.col.pk).values("pk")
)
cte = With.recursive(make_regions_cte)
queryset = cte.queryset().with_cte(cte).order_by("pk")
print(queryset.query)
self.assertEqual(list(queryset), [
{'pk': 'earth'},
{'pk': 'moon'},
])
|
