# Copyright (c) 2020, 2022, Oracle and/or its affiliates.
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#
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# This program is free software; you can redistribute it and/or modify
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# it under the terms of the GNU General Public License, version 2.0, as
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# published by the Free Software Foundation.
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#
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# This program is also distributed with certain software (including
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# but not limited to OpenSSL) that is licensed under separate terms,
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# as designated in a particular file or component or in included license
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# documentation. The authors of MySQL hereby grant you an
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# additional permission to link the program and your derivative works
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# with the separately licensed software that they have included with
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# MySQL.
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#
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# Without limiting anything contained in the foregoing, this file,
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# which is part of MySQL Connector/Python, is also subject to the
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# Universal FOSS Exception, version 1.0, a copy of which can be found at
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# http://oss.oracle.com/licenses/universal-foss-exception.
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#
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# This program is distributed in the hope that it will be useful, but
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# WITHOUT ANY WARRANTY; without even the implied warranty of
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# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.
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# See the GNU General Public License, version 2.0, for more details.
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#
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# You should have received a copy of the GNU General Public License
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# along with this program; if not, write to the Free Software Foundation, Inc.,
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# 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA
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# mypy: disable-error-code="override,attr-defined,call-arg"
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"""Database Introspection."""
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from collections import namedtuple
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from typing import TYPE_CHECKING, Any, Dict, List, Optional, Set, Tuple
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import sqlparse
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from django import VERSION as DJANGO_VERSION
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from django.db.backends.base.introspection import (
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BaseDatabaseIntrospection,
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FieldInfo as BaseFieldInfo,
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TableInfo,
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)
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from django.db.models import Index
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from django.utils.datastructures import OrderedSet
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from mysql.connector.constants import FieldType
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# from .base import CursorWrapper produces a circular import error,
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# avoiding importing CursorWrapper explicitly, using a documented
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# trick; write the imports inside if TYPE_CHECKING: so that they
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# are not executed at runtime.
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# Ref: https://buildmedia.readthedocs.org/media/pdf/mypy/stable/mypy.pdf [page 42]
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if TYPE_CHECKING:
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# CursorWraper is used exclusively for type hinting
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from mysql.connector.django.base import CursorWrapper
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# Based on my investigation, named tuples to
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# comply with mypy need to define a static list or tuple
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# for field_names (second argument). In this case, the field
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# names are created dynamically for FieldInfo which triggers
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# a mypy error. The solution is not straightforward since
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# FieldInfo attributes are Django version dependent. Code
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# refactory is needed to fix this issue.
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FieldInfo = namedtuple( # type: ignore[misc]
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"FieldInfo",
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BaseFieldInfo._fields + ("extra", "is_unsigned", "has_json_constraint"),
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)
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if DJANGO_VERSION < (3, 2, 0):
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InfoLine = namedtuple(
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"InfoLine",
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"col_name data_type max_len num_prec num_scale extra column_default "
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"is_unsigned",
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)
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else:
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InfoLine = namedtuple( # type: ignore[no-redef]
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"InfoLine",
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"col_name data_type max_len num_prec num_scale extra column_default "
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"collation is_unsigned",
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)
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class DatabaseIntrospection(BaseDatabaseIntrospection):
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"""Encapsulate backend-specific introspection utilities."""
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data_types_reverse = {
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FieldType.BLOB: "TextField",
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FieldType.DECIMAL: "DecimalField",
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FieldType.NEWDECIMAL: "DecimalField",
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FieldType.DATE: "DateField",
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FieldType.DATETIME: "DateTimeField",
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FieldType.DOUBLE: "FloatField",
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FieldType.FLOAT: "FloatField",
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FieldType.INT24: "IntegerField",
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FieldType.LONG: "IntegerField",
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FieldType.LONGLONG: "BigIntegerField",
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FieldType.SHORT: "SmallIntegerField",
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FieldType.STRING: "CharField",
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FieldType.TIME: "TimeField",
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FieldType.TIMESTAMP: "DateTimeField",
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FieldType.TINY: "IntegerField",
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FieldType.TINY_BLOB: "TextField",
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FieldType.MEDIUM_BLOB: "TextField",
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FieldType.LONG_BLOB: "TextField",
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FieldType.VAR_STRING: "CharField",
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}
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def get_field_type(self, data_type: str, description: FieldInfo) -> str:
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field_type = super().get_field_type(data_type, description) # type: ignore[arg-type]
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if "auto_increment" in description.extra:
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if field_type == "IntegerField":
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return "AutoField"
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if field_type == "BigIntegerField":
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return "BigAutoField"
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if field_type == "SmallIntegerField":
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return "SmallAutoField"
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if description.is_unsigned:
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if field_type == "BigIntegerField":
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return "PositiveBigIntegerField"
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if field_type == "IntegerField":
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return "PositiveIntegerField"
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if field_type == "SmallIntegerField":
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return "PositiveSmallIntegerField"
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# JSON data type is an alias for LONGTEXT in MariaDB, use check
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# constraints clauses to introspect JSONField.
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if description.has_json_constraint:
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return "JSONField"
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return field_type
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def get_table_list(self, cursor: "CursorWrapper") -> List[TableInfo]:
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"""Return a list of table and view names in the current database."""
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cursor.execute("SHOW FULL TABLES")
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return [
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TableInfo(row[0], {"BASE TABLE": "t", "VIEW": "v"}.get(row[1]))
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for row in cursor.fetchall()
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]
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def get_table_description(
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self, cursor: "CursorWrapper", table_name: str
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) -> List[FieldInfo]:
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"""
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Return a description of the table with the DB-API cursor.description
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interface."
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"""
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json_constraints: Dict[Any, Any] = {}
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# A default collation for the given table.
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cursor.execute(
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"""
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SELECT table_collation
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FROM information_schema.tables
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WHERE table_schema = DATABASE()
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AND table_name = %s
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""",
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[table_name],
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)
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row = cursor.fetchone()
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default_column_collation = row[0] if row else ""
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# information_schema database gives more accurate results for some figures:
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# - varchar length returned by cursor.description is an internal length,
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# not visible length (#5725)
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# - precision and scale (for decimal fields) (#5014)
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# - auto_increment is not available in cursor.description
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if DJANGO_VERSION < (3, 2, 0):
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cursor.execute(
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"""
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SELECT
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column_name, data_type, character_maximum_length,
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numeric_precision, numeric_scale, extra, column_default,
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CASE
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WHEN column_type LIKE '%% unsigned' THEN 1
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ELSE 0
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END AS is_unsigned
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FROM information_schema.columns
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WHERE table_name = %s AND table_schema = DATABASE()
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""",
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[table_name],
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)
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else:
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cursor.execute(
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"""
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SELECT
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column_name, data_type, character_maximum_length,
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numeric_precision, numeric_scale, extra, column_default,
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CASE
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WHEN collation_name = %s THEN NULL
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ELSE collation_name
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END AS collation_name,
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CASE
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WHEN column_type LIKE '%% unsigned' THEN 1
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ELSE 0
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END AS is_unsigned
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FROM information_schema.columns
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WHERE table_name = %s AND table_schema = DATABASE()
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""",
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[default_column_collation, table_name],
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)
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field_info = {line[0]: InfoLine(*line) for line in cursor.fetchall()}
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cursor.execute(
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f"SELECT * FROM {self.connection.ops.quote_name(table_name)} LIMIT 1"
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)
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def to_int(i: Any) -> Optional[int]:
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return int(i) if i is not None else i
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fields = []
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for line in cursor.description:
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info = field_info[line[0]]
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if DJANGO_VERSION < (3, 2, 0):
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fields.append(
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FieldInfo(
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*line[:3],
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to_int(info.max_len) or line[3],
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to_int(info.num_prec) or line[4],
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to_int(info.num_scale) or line[5],
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line[6],
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info.column_default,
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info.extra,
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info.is_unsigned,
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line[0] in json_constraints,
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)
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)
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else:
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fields.append(
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FieldInfo(
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*line[:3],
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to_int(info.max_len) or line[3],
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to_int(info.num_prec) or line[4],
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to_int(info.num_scale) or line[5],
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line[6],
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info.column_default,
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info.collation,
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info.extra,
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info.is_unsigned,
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line[0] in json_constraints,
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)
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)
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return fields
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def get_indexes(
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self, cursor: "CursorWrapper", table_name: str
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) -> Dict[int, Dict[str, bool]]:
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"""Return indexes from table."""
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cursor.execute(f"SHOW INDEX FROM {self.connection.ops.quote_name(table_name)}")
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# Do a two-pass search for indexes: on first pass check which indexes
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# are multicolumn, on second pass check which single-column indexes
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# are present.
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rows = list(cursor.fetchall())
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multicol_indexes = set()
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for row in rows:
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if row[3] > 1:
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multicol_indexes.add(row[2])
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indexes: Dict[int, Dict[str, bool]] = {}
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for row in rows:
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if row[2] in multicol_indexes:
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continue
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if row[4] not in indexes:
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indexes[row[4]] = {"primary_key": False, "unique": False}
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# It's possible to have the unique and PK constraints in
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# separate indexes.
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if row[2] == "PRIMARY":
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indexes[row[4]]["primary_key"] = True
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if not row[1]:
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indexes[row[4]]["unique"] = True
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return indexes
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def get_primary_key_column(
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self, cursor: "CursorWrapper", table_name: str
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) -> Optional[int]:
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"""
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Returns the name of the primary key column for the given table
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"""
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for column in self.get_indexes(cursor, table_name).items():
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if column[1]["primary_key"]:
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return column[0]
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return None
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def get_sequences(
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self, cursor: "CursorWrapper", table_name: str, table_fields: Any = ()
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) -> List[Dict[str, str]]:
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for field_info in self.get_table_description(cursor, table_name):
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if "auto_increment" in field_info.extra:
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# MySQL allows only one auto-increment column per table.
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return [{"table": table_name, "column": field_info.name}]
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return []
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def get_relations(
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self, cursor: "CursorWrapper", table_name: str
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) -> Dict[str, Tuple[str, str]]:
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"""
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Return a dictionary of {field_name: (field_name_other_table, other_table)}
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representing all relationships to the given table.
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"""
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constraints = self.get_key_columns(cursor, table_name)
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relations = {}
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for my_fieldname, other_table, other_field in constraints:
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relations[my_fieldname] = (other_field, other_table)
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return relations
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def get_key_columns(
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self, cursor: "CursorWrapper", table_name: str
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) -> List[Tuple[str, str, str]]:
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"""
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Return a list of (column_name, referenced_table_name, referenced_column_name)
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for all key columns in the given table.
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"""
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key_columns: List[Any] = []
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cursor.execute(
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"""
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SELECT column_name, referenced_table_name, referenced_column_name
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FROM information_schema.key_column_usage
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WHERE table_name = %s
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AND table_schema = DATABASE()
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AND referenced_table_name IS NOT NULL
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AND referenced_column_name IS NOT NULL""",
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[table_name],
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)
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key_columns.extend(cursor.fetchall())
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return key_columns
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def get_storage_engine(self, cursor: "CursorWrapper", table_name: str) -> str:
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"""
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Retrieve the storage engine for a given table. Return the default
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storage engine if the table doesn't exist.
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"""
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cursor.execute(
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"SELECT engine FROM information_schema.tables WHERE table_name = %s",
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[table_name],
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)
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result = cursor.fetchone()
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# pylint: disable=protected-access
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if not result:
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return self.connection.features._mysql_storage_engine
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# pylint: enable=protected-access
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return result[0]
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def _parse_constraint_columns(
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self, check_clause: Any, columns: Set[str]
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) -> OrderedSet:
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check_columns: OrderedSet = OrderedSet()
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statement = sqlparse.parse(check_clause)[0]
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tokens = (token for token in statement.flatten() if not token.is_whitespace)
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for token in tokens:
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if (
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token.ttype == sqlparse.tokens.Name
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and self.connection.ops.quote_name(token.value) == token.value
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and token.value[1:-1] in columns
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):
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check_columns.add(token.value[1:-1])
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return check_columns
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def get_constraints(
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self, cursor: "CursorWrapper", table_name: str
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) -> Dict[str, Any]:
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"""
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Retrieve any constraints or keys (unique, pk, fk, check, index) across
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one or more columns.
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"""
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constraints: Dict[str, Any] = {}
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# Get the actual constraint names and columns
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name_query = """
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SELECT kc.`constraint_name`, kc.`column_name`,
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kc.`referenced_table_name`, kc.`referenced_column_name`
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FROM information_schema.key_column_usage AS kc
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WHERE
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kc.table_schema = DATABASE() AND
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kc.table_name = %s
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ORDER BY kc.`ordinal_position`
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"""
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cursor.execute(name_query, [table_name])
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for constraint, column, ref_table, ref_column in cursor.fetchall():
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if constraint not in constraints:
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constraints[constraint] = {
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"columns": OrderedSet(),
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"primary_key": False,
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"unique": False,
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"index": False,
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"check": False,
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"foreign_key": (ref_table, ref_column) if ref_column else None,
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}
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if self.connection.features.supports_index_column_ordering:
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constraints[constraint]["orders"] = []
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constraints[constraint]["columns"].add(column)
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# Now get the constraint types
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type_query = """
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SELECT c.constraint_name, c.constraint_type
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FROM information_schema.table_constraints AS c
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WHERE
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c.table_schema = DATABASE() AND
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c.table_name = %s
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"""
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cursor.execute(type_query, [table_name])
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for constraint, kind in cursor.fetchall():
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if kind.lower() == "primary key":
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constraints[constraint]["primary_key"] = True
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constraints[constraint]["unique"] = True
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elif kind.lower() == "unique":
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constraints[constraint]["unique"] = True
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# Add check constraints.
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if self.connection.features.can_introspect_check_constraints:
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unnamed_constraints_index = 0
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columns = {
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info.name for info in self.get_table_description(cursor, table_name)
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}
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type_query = """
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SELECT cc.constraint_name, cc.check_clause
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FROM
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information_schema.check_constraints AS cc,
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information_schema.table_constraints AS tc
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WHERE
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cc.constraint_schema = DATABASE() AND
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tc.table_schema = cc.constraint_schema AND
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cc.constraint_name = tc.constraint_name AND
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tc.constraint_type = 'CHECK' AND
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tc.table_name = %s
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"""
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cursor.execute(type_query, [table_name])
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for constraint, check_clause in cursor.fetchall():
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constraint_columns = self._parse_constraint_columns(
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check_clause, columns
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)
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# Ensure uniqueness of unnamed constraints. Unnamed unique
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# and check columns constraints have the same name as
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# a column.
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if set(constraint_columns) == {constraint}:
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unnamed_constraints_index += 1
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constraint = f"__unnamed_constraint_{unnamed_constraints_index}__"
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constraints[constraint] = {
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"columns": constraint_columns,
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"primary_key": False,
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"unique": False,
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"index": False,
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"check": True,
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"foreign_key": None,
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}
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# Now add in the indexes
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cursor.execute(f"SHOW INDEX FROM {self.connection.ops.quote_name(table_name)}")
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for _, _, index, _, column, order, type_ in [
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x[:6] + (x[10],) for x in cursor.fetchall()
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]:
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if index not in constraints:
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constraints[index] = {
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"columns": OrderedSet(),
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"primary_key": False,
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"unique": False,
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"check": False,
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"foreign_key": None,
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}
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if self.connection.features.supports_index_column_ordering:
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constraints[index]["orders"] = []
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constraints[index]["index"] = True
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constraints[index]["type"] = (
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Index.suffix if type_ == "BTREE" else type_.lower()
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)
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constraints[index]["columns"].add(column)
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if self.connection.features.supports_index_column_ordering:
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constraints[index]["orders"].append("DESC" if order == "D" else "ASC")
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# Convert the sorted sets to lists
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for constraint in constraints.values():
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constraint["columns"] = list(constraint["columns"])
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return constraints
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