1from __future__ import annotations
 2
 3import operator
 4from functools import cached_property
 5
 6from plain.models import transaction
 7from plain.models.backends.base.features import BaseDatabaseFeatures
 8from plain.models.db import OperationalError
 9
10from .base import Database
11
12
13class DatabaseFeatures(BaseDatabaseFeatures):
14    minimum_database_version = (3, 21)
15    max_query_params = 999
16    supports_transactions = True
17    can_rollback_ddl = True
18    requires_literal_defaults = True
19    supports_temporal_subtraction = True
20    ignores_table_name_case = True
21    # Is "ALTER TABLE ... RENAME COLUMN" supported?
22    can_alter_table_rename_column = Database.sqlite_version_info >= (3, 25, 0)
23    # Is "ALTER TABLE ... DROP COLUMN" supported?
24    can_alter_table_drop_column = Database.sqlite_version_info >= (3, 35, 5)
25    supports_parentheses_in_compound = False
26    can_defer_constraint_checks = True
27    supports_over_clause = Database.sqlite_version_info >= (3, 25, 0)
28    supports_aggregate_filter_clause = Database.sqlite_version_info >= (3, 30, 1)
29    supports_order_by_nulls_modifier = Database.sqlite_version_info >= (3, 30, 0)
30    # NULLS LAST/FIRST emulation on < 3.30 requires subquery wrapping.
31    requires_compound_order_by_subquery = Database.sqlite_version_info < (3, 30)
32    order_by_nulls_first = True
33    supports_json_field_contains = False
34    supports_update_conflicts = Database.sqlite_version_info >= (3, 24, 0)
35    supports_update_conflicts_with_target = supports_update_conflicts
36    supports_unlimited_charfield = True
37
38    @cached_property
39    def supports_atomic_references_rename(self) -> bool:
40        return Database.sqlite_version_info >= (3, 26, 0)
41
42    @cached_property
43    def supports_json_field(self) -> bool:
44        with self.connection.cursor() as cursor:
45            try:
46                with transaction.atomic():
47                    cursor.execute('SELECT JSON(\'{"a": "b"}\')')
48            except OperationalError:
49                return False
50        return True
51
52    can_introspect_json_field = property(operator.attrgetter("supports_json_field"))
53    has_json_object_function = property(operator.attrgetter("supports_json_field"))
54
55    @cached_property
56    def can_return_columns_from_insert(self) -> bool:
57        return Database.sqlite_version_info >= (3, 35)
58
59    can_return_rows_from_bulk_insert = property(
60        operator.attrgetter("can_return_columns_from_insert")
61    )