1import operator
 2from functools import cached_property
 3
 4from plain.models import transaction
 5from plain.models.backends.base.features import BaseDatabaseFeatures
 6from plain.models.db import OperationalError
 7
 8from .base import Database
 9
10
11class DatabaseFeatures(BaseDatabaseFeatures):
12    minimum_database_version = (3, 21)
13    max_query_params = 999
14    supports_transactions = True
15    can_rollback_ddl = True
16    requires_literal_defaults = True
17    supports_temporal_subtraction = True
18    ignores_table_name_case = True
19    # Is "ALTER TABLE ... RENAME COLUMN" supported?
20    can_alter_table_rename_column = Database.sqlite_version_info >= (3, 25, 0)
21    # Is "ALTER TABLE ... DROP COLUMN" supported?
22    can_alter_table_drop_column = Database.sqlite_version_info >= (3, 35, 5)
23    supports_parentheses_in_compound = False
24    can_defer_constraint_checks = True
25    supports_over_clause = Database.sqlite_version_info >= (3, 25, 0)
26    supports_aggregate_filter_clause = Database.sqlite_version_info >= (3, 30, 1)
27    supports_order_by_nulls_modifier = Database.sqlite_version_info >= (3, 30, 0)
28    # NULLS LAST/FIRST emulation on < 3.30 requires subquery wrapping.
29    requires_compound_order_by_subquery = Database.sqlite_version_info < (3, 30)
30    order_by_nulls_first = True
31    supports_json_field_contains = False
32    supports_update_conflicts = Database.sqlite_version_info >= (3, 24, 0)
33    supports_update_conflicts_with_target = supports_update_conflicts
34
35    @cached_property
36    def supports_atomic_references_rename(self):
37        return Database.sqlite_version_info >= (3, 26, 0)
38
39    @cached_property
40    def supports_json_field(self):
41        with self.connection.cursor() as cursor:
42            try:
43                with transaction.atomic():
44                    cursor.execute('SELECT JSON(\'{"a": "b"}\')')
45            except OperationalError:
46                return False
47        return True
48
49    can_introspect_json_field = property(operator.attrgetter("supports_json_field"))
50    has_json_object_function = property(operator.attrgetter("supports_json_field"))
51
52    @cached_property
53    def can_return_columns_from_insert(self):
54        return Database.sqlite_version_info >= (3, 35)
55
56    can_return_rows_from_bulk_insert = property(
57        operator.attrgetter("can_return_columns_from_insert")
58    )