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Fixed #30062 -- Added support for unique conditional constraints.

This commit is contained in:
Paveł Tyślacki 2018-12-27 22:21:59 +03:00 committed by Tim Graham
parent 1e837c4b23
commit b69f8eb04c
8 changed files with 291 additions and 26 deletions
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50
django/db/backends/base/schema.py
View File

@ -80,6 +80,7 @@ class BaseDatabaseSchemaEditor:
sql_delete_fk = sql_delete_constraint
sql_create_index = "CREATE INDEX %(name)s ON %(table)s (%(columns)s)%(extra)s%(condition)s"
sql_create_unique_index = "CREATE UNIQUE INDEX %(name)s ON %(table)s (%(columns)s)%(condition)s"
sql_delete_index = "DROP INDEX %(name)s"
sql_create_pk = "ALTER TABLE %(table)s ADD CONSTRAINT %(name)s PRIMARY KEY (%(columns)s)"
@ -296,7 +297,7 @@ class BaseDatabaseSchemaEditor:
# Make the table
sql = self.sql_create_table % {
"table": self.quote_name(model._meta.db_table),
"definition": ", ".join((*column_sqls, *constraints)),
"definition": ", ".join(constraint for constraint in (*column_sqls, *constraints) if constraint),
}
if model._meta.db_tablespace:
tablespace_sql = self.connection.ops.tablespace_sql(model._meta.db_tablespace)
@ -339,11 +340,15 @@ class BaseDatabaseSchemaEditor:
def add_constraint(self, model, constraint):
"""Add a check constraint to a model."""
self.execute(constraint.create_sql(model, self))
sql = constraint.create_sql(model, self)
if sql:
self.execute(sql)
def remove_constraint(self, model, constraint):
"""Remove a check constraint from a model."""
self.execute(constraint.remove_sql(model, self))
sql = constraint.remove_sql(model, self)
if sql:
self.execute(sql)
def alter_unique_together(self, model, old_unique_together, new_unique_together):
"""
@ -1008,7 +1013,14 @@ class BaseDatabaseSchemaEditor:
def _delete_fk_sql(self, model, name):
return self._delete_constraint_sql(self.sql_delete_fk, model, name)
def _unique_sql(self, fields, name):
def _unique_sql(self, model, fields, name, condition=None):
if condition:
# Databases support conditional unique constraints via a unique
# index.
sql = self._create_unique_sql(model, fields, name=name, condition=condition)
if sql:
self.deferred_sql.append(sql)
return None
constraint = self.sql_unique_constraint % {
'columns': ', '.join(map(self.quote_name, fields)),
}
@ -1017,7 +1029,7 @@ class BaseDatabaseSchemaEditor:
'constraint': constraint,
}
def _create_unique_sql(self, model, columns, name=None):
def _create_unique_sql(self, model, columns, name=None, condition=None):
def create_unique_name(*args, **kwargs):
return self.quote_name(self._create_index_name(*args, **kwargs))
@ -1027,14 +1039,28 @@ class BaseDatabaseSchemaEditor:
else:
name = self.quote_name(name)
columns = Columns(table, columns, self.quote_name)
return Statement(
self.sql_create_unique,
table=table,
name=name,
columns=columns,
)
if condition:
return Statement(
self.sql_create_unique_index,
table=table,
name=name,
columns=columns,
condition=' WHERE ' + condition,
) if self.connection.features.supports_partial_indexes else None
else:
return Statement(
self.sql_create_unique,
table=table,
name=name,
columns=columns,
)
def _delete_unique_sql(self, model, name):
def _delete_unique_sql(self, model, name, condition=None):
if condition:
return (
self._delete_constraint_sql(self.sql_delete_index, model, name)
if self.connection.features.supports_partial_indexes else None
)
return self._delete_constraint_sql(self.sql_delete_unique, model, name)
def _check_sql(self, name, check):

11
django/db/backends/sqlite3/schema.py
View File

@ -4,6 +4,7 @@ from decimal import Decimal
from django.apps.registry import Apps
from django.db.backends.base.schema import BaseDatabaseSchemaEditor
from django.db.backends.ddl_references import Statement
from django.db.models import UniqueConstraint
from django.db.transaction import atomic
from django.db.utils import NotSupportedError
@ -398,7 +399,13 @@ class DatabaseSchemaEditor(BaseDatabaseSchemaEditor):
self.delete_model(old_field.remote_field.through)
def add_constraint(self, model, constraint):
self._remake_table(model)
if isinstance(constraint, UniqueConstraint) and constraint.condition:
super().add_constraint(model, constraint)
else:
self._remake_table(model)
def remove_constraint(self, model, constraint):
self._remake_table(model)
if isinstance(constraint, UniqueConstraint) and constraint.condition:
super().remove_constraint(model, constraint)
else:
self._remake_table(model)

2
django/db/models/base.py
View File

@ -1009,6 +1009,8 @@ class Model(metaclass=ModelBase):
for model_class, model_constraints in constraints:
for constraint in model_constraints:
if (isinstance(constraint, UniqueConstraint) and
# Partial unique constraints can't be validated.
constraint.condition is None and
not any(name in exclude for name in constraint.fields)):
unique_checks.append((model_class, constraint.fields))

34
django/db/models/constraints.py
View File

@ -1,3 +1,4 @@
from django.db.models.query_utils import Q
from django.db.models.sql.query import Query
__all__ = ['CheckConstraint', 'UniqueConstraint']
@ -66,34 +67,55 @@ class CheckConstraint(BaseConstraint):
class UniqueConstraint(BaseConstraint):
def __init__(self, *, fields, name):
def __init__(self, *, fields, name, condition=None):
if not fields:
raise ValueError('At least one field is required to define a unique constraint.')
if not isinstance(condition, (type(None), Q)):
raise ValueError('UniqueConstraint.condition must be a Q instance.')
self.fields = tuple(fields)
self.condition = condition
super().__init__(name)
def _get_condition_sql(self, model, schema_editor):
if self.condition is None:
return None
query = Query(model=model)
where = query.build_where(self.condition)
compiler = query.get_compiler(connection=schema_editor.connection)
sql, params = where.as_sql(compiler, schema_editor.connection)
return sql % tuple(schema_editor.quote_value(p) for p in params)
def constraint_sql(self, model, schema_editor):
fields = [model._meta.get_field(field_name).column for field_name in self.fields]
return schema_editor._unique_sql(fields, self.name)
condition = self._get_condition_sql(model, schema_editor)
return schema_editor._unique_sql(model, fields, self.name, condition=condition)
def create_sql(self, model, schema_editor):
fields = [model._meta.get_field(field_name).column for field_name in self.fields]
return schema_editor._create_unique_sql(model, fields, self.name)
condition = self._get_condition_sql(model, schema_editor)
return schema_editor._create_unique_sql(model, fields, self.name, condition=condition)
def remove_sql(self, model, schema_editor):
return schema_editor._delete_unique_sql(model, self.name)
condition = self._get_condition_sql(model, schema_editor)
return schema_editor._delete_unique_sql(model, self.name, condition=condition)
def __repr__(self):
return '<%s: fields=%r name=%r>' % (self.__class__.__name__, self.fields, self.name)
return '<%s: fields=%r name=%r%s>' % (
self.__class__.__name__, self.fields, self.name,
'' if self.condition is None else ' condition=%s' % self.condition,
)
def __eq__(self, other):
return (
isinstance(other, UniqueConstraint) and
self.name == other.name and
self.fields == other.fields
self.fields == other.fields and
self.condition == other.condition
)
def deconstruct(self):
path, args, kwargs = super().deconstruct()
kwargs['fields'] = self.fields
if self.condition:
kwargs['condition'] = self.condition
return path, args, kwargs

14
docs/ref/models/constraints.txt
View File

@ -69,3 +69,17 @@ date.
.. attribute:: UniqueConstraint.name
The name of the constraint.
``condition``
-------------
.. attribute:: UniqueConstraint.condition
A :class:`Q` object that specifies the condition you want the constraint to
enforce.
For example, ``UniqueConstraint(fields=['user'], condition=Q(status='DRAFT')``
ensures that each user only has one draft.
These conditions have the same database restrictions as
:attr:`Index.condition`.

8
tests/constraints/models.py
View File

@ -3,6 +3,7 @@ from django.db import models
class Product(models.Model):
name = models.CharField(max_length=255)
color = models.CharField(max_length=32, null=True)
price = models.IntegerField(null=True)
discounted_price = models.IntegerField(null=True)
@ -12,5 +13,10 @@ class Product(models.Model):
check=models.Q(price__gt=models.F('discounted_price')),
name='price_gt_discounted_price',
),
models.UniqueConstraint(fields=['name'], name='unique_name'),
models.UniqueConstraint(fields=['name', 'color'], name='name_color_uniq'),
models.UniqueConstraint(
fields=['name'],
name='name_without_color_uniq',
condition=models.Q(color__isnull=True),
),
]

67
tests/constraints/tests.py
View File

@ -83,7 +83,10 @@ class CheckConstraintTests(TestCase):
class UniqueConstraintTests(TestCase):
@classmethod
def setUpTestData(cls):
cls.p1 = Product.objects.create(name='p1')
cls.p1, cls.p2 = Product.objects.bulk_create([
Product(name='p1', color='red'),
Product(name='p2'),
])
def test_eq(self):
self.assertEqual(
@ -100,6 +103,29 @@ class UniqueConstraintTests(TestCase):
)
self.assertNotEqual(models.UniqueConstraint(fields=['foo', 'bar'], name='unique'), 1)
def test_eq_with_condition(self):
self.assertEqual(
models.UniqueConstraint(
fields=['foo', 'bar'], name='unique',
condition=models.Q(foo=models.F('bar'))
),
models.UniqueConstraint(
fields=['foo', 'bar'], name='unique',
condition=models.Q(foo=models.F('bar'))),
)
self.assertNotEqual(
models.UniqueConstraint(
fields=['foo', 'bar'],
name='unique',
condition=models.Q(foo=models.F('bar'))
),
models.UniqueConstraint(
fields=['foo', 'bar'],
name='unique',
condition=models.Q(foo=models.F('baz'))
),
)
def test_repr(self):
fields = ['foo', 'bar']
name = 'unique_fields'
@ -109,6 +135,18 @@ class UniqueConstraintTests(TestCase):
"<UniqueConstraint: fields=('foo', 'bar') name='unique_fields'>",
)
def test_repr_with_condition(self):
constraint = models.UniqueConstraint(
fields=['foo', 'bar'],
name='unique_fields',
condition=models.Q(foo=models.F('bar')),
)
self.assertEqual(
repr(constraint),
"<UniqueConstraint: fields=('foo', 'bar') name='unique_fields' "
"condition=(AND: ('foo', F(bar)))>",
)
def test_deconstruction(self):
fields = ['foo', 'bar']
name = 'unique_fields'
@ -118,15 +156,34 @@ class UniqueConstraintTests(TestCase):
self.assertEqual(args, ())
self.assertEqual(kwargs, {'fields': tuple(fields), 'name': name})
def test_deconstruction_with_condition(self):
fields = ['foo', 'bar']
name = 'unique_fields'
condition = models.Q(foo=models.F('bar'))
constraint = models.UniqueConstraint(fields=fields, name=name, condition=condition)
path, args, kwargs = constraint.deconstruct()
self.assertEqual(path, 'django.db.models.UniqueConstraint')
self.assertEqual(args, ())
self.assertEqual(kwargs, {'fields': tuple(fields), 'name': name, 'condition': condition})
def test_database_constraint(self):
with self.assertRaises(IntegrityError):
Product.objects.create(name=self.p1.name)
Product.objects.create(name=self.p1.name, color=self.p1.color)
def test_model_validation(self):
with self.assertRaisesMessage(ValidationError, 'Product with this Name already exists.'):
Product(name=self.p1.name).validate_unique()
with self.assertRaisesMessage(ValidationError, 'Product with this Name and Color already exists.'):
Product(name=self.p1.name, color=self.p1.color).validate_unique()
def test_model_validation_with_condition(self):
"""Partial unique constraints are ignored by Model.validate_unique()."""
Product(name=self.p1.name, color='blue').validate_unique()
Product(name=self.p2.name).validate_unique()
def test_name(self):
constraints = get_constraints(Product._meta.db_table)
expected_name = 'unique_name'
expected_name = 'name_color_uniq'
self.assertIn(expected_name, constraints)
def test_condition_must_be_q(self):
with self.assertRaisesMessage(ValueError, 'UniqueConstraint.condition must be a Q instance.'):
models.UniqueConstraint(name='uniq', fields=['name'], condition='invalid')

131
tests/migrations/test_operations.py
View File

@ -501,6 +501,51 @@ class OperationTests(OperationTestBase):
self.assertEqual(definition[1], [])
self.assertEqual(definition[2]['options']['constraints'], [check_constraint])
def test_create_model_with_partial_unique_constraint(self):
partial_unique_constraint = models.UniqueConstraint(
fields=['pink'],
condition=models.Q(weight__gt=5),
name='test_constraint_pony_pink_for_weight_gt_5_uniq',
)
operation = migrations.CreateModel(
'Pony',
[
('id', models.AutoField(primary_key=True)),
('pink', models.IntegerField(default=3)),
('weight', models.FloatField()),
],
options={'constraints': [partial_unique_constraint]},
)
# Test the state alteration
project_state = ProjectState()
new_state = project_state.clone()
operation.state_forwards('test_crmo', new_state)
self.assertEqual(len(new_state.models['test_crmo', 'pony'].options['constraints']), 1)
# Test database alteration
self.assertTableNotExists('test_crmo_pony')
with connection.schema_editor() as editor:
operation.database_forwards('test_crmo', editor, project_state, new_state)
self.assertTableExists('test_crmo_pony')
# Test constraint works
Pony = new_state.apps.get_model('test_crmo', 'Pony')
Pony.objects.create(pink=1, weight=4.0)
Pony.objects.create(pink=1, weight=4.0)
Pony.objects.create(pink=1, weight=6.0)
if connection.features.supports_partial_indexes:
with self.assertRaises(IntegrityError):
Pony.objects.create(pink=1, weight=7.0)
else:
Pony.objects.create(pink=1, weight=7.0)
# Test reversal
with connection.schema_editor() as editor:
operation.database_backwards('test_crmo', editor, new_state, project_state)
self.assertTableNotExists('test_crmo_pony')
# Test deconstruction
definition = operation.deconstruct()
self.assertEqual(definition[0], 'CreateModel')
self.assertEqual(definition[1], [])
self.assertEqual(definition[2]['options']['constraints'], [partial_unique_constraint])
def test_create_model_managers(self):
"""
The managers on a model are set.
@ -1854,6 +1899,92 @@ class OperationTests(OperationTestBase):
self.assertEqual(definition[1], [])
self.assertEqual(definition[2], {'model_name': "Pony", 'name': "test_remove_constraint_pony_pink_gt_2"})
def test_add_partial_unique_constraint(self):
project_state = self.set_up_test_model('test_addpartialuniqueconstraint')
partial_unique_constraint = models.UniqueConstraint(
fields=['pink'],
condition=models.Q(weight__gt=5),
name='test_constraint_pony_pink_for_weight_gt_5_uniq',
)
operation = migrations.AddConstraint('Pony', partial_unique_constraint)
self.assertEqual(
operation.describe(),
'Create constraint test_constraint_pony_pink_for_weight_gt_5_uniq '
'on model Pony'
)
# Test the state alteration
new_state = project_state.clone()
operation.state_forwards('test_addpartialuniqueconstraint', new_state)
self.assertEqual(len(new_state.models['test_addpartialuniqueconstraint', 'pony'].options['constraints']), 1)
Pony = new_state.apps.get_model('test_addpartialuniqueconstraint', 'Pony')
self.assertEqual(len(Pony._meta.constraints), 1)
# Test the database alteration
with connection.schema_editor() as editor:
operation.database_forwards('test_addpartialuniqueconstraint', editor, project_state, new_state)
# Test constraint works
Pony.objects.create(pink=1, weight=4.0)
Pony.objects.create(pink=1, weight=4.0)
Pony.objects.create(pink=1, weight=6.0)
if connection.features.supports_partial_indexes:
with self.assertRaises(IntegrityError), transaction.atomic():
Pony.objects.create(pink=1, weight=7.0)
else:
Pony.objects.create(pink=1, weight=7.0)
# Test reversal
with connection.schema_editor() as editor:
operation.database_backwards('test_addpartialuniqueconstraint', editor, new_state, project_state)
# Test constraint doesn't work
Pony.objects.create(pink=1, weight=7.0)
# Test deconstruction
definition = operation.deconstruct()
self.assertEqual(definition[0], 'AddConstraint')
self.assertEqual(definition[1], [])
self.assertEqual(definition[2], {'model_name': 'Pony', 'constraint': partial_unique_constraint})
def test_remove_partial_unique_constraint(self):
project_state = self.set_up_test_model('test_removepartialuniqueconstraint', constraints=[
models.UniqueConstraint(
fields=['pink'],
condition=models.Q(weight__gt=5),
name='test_constraint_pony_pink_for_weight_gt_5_uniq',
),
])
gt_operation = migrations.RemoveConstraint('Pony', 'test_constraint_pony_pink_for_weight_gt_5_uniq')
self.assertEqual(
gt_operation.describe(), 'Remove constraint test_constraint_pony_pink_for_weight_gt_5_uniq from model Pony'
)
# Test state alteration
new_state = project_state.clone()
gt_operation.state_forwards('test_removepartialuniqueconstraint', new_state)
self.assertEqual(len(new_state.models['test_removepartialuniqueconstraint', 'pony'].options['constraints']), 0)
Pony = new_state.apps.get_model('test_removepartialuniqueconstraint', 'Pony')
self.assertEqual(len(Pony._meta.constraints), 0)
# Test database alteration
with connection.schema_editor() as editor:
gt_operation.database_forwards('test_removepartialuniqueconstraint', editor, project_state, new_state)
# Test constraint doesn't work
Pony.objects.create(pink=1, weight=4.0)
Pony.objects.create(pink=1, weight=4.0)
Pony.objects.create(pink=1, weight=6.0)
Pony.objects.create(pink=1, weight=7.0).delete()
# Test reversal
with connection.schema_editor() as editor:
gt_operation.database_backwards('test_removepartialuniqueconstraint', editor, new_state, project_state)
# Test constraint works
if connection.features.supports_partial_indexes:
with self.assertRaises(IntegrityError), transaction.atomic():
Pony.objects.create(pink=1, weight=7.0)
else:
Pony.objects.create(pink=1, weight=7.0)
# Test deconstruction
definition = gt_operation.deconstruct()
self.assertEqual(definition[0], 'RemoveConstraint')
self.assertEqual(definition[1], [])
self.assertEqual(definition[2], {
'model_name': 'Pony',
'name': 'test_constraint_pony_pink_for_weight_gt_5_uniq',
})
def test_alter_model_options(self):
"""
Tests the AlterModelOptions operation.