6789ded0a6
Thanks to Adam Johnson, Carlton Gibson, Mariusz Felisiak, and Raphael Michel for mentoring this Google Summer of Code 2019 project and everyone else who helped with the patch. Special thanks to Mads Jensen, Nick Pope, and Simon Charette for extensive reviews. Co-authored-by: Mariusz Felisiak <felisiak.mariusz@gmail.com>
380 lines
15 KiB
Python
380 lines
15 KiB
Python
"""
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MySQL database backend for Django.
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Requires mysqlclient: https://pypi.org/project/mysqlclient/
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"""
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from django.core.exceptions import ImproperlyConfigured
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from django.db import IntegrityError
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from django.db.backends import utils as backend_utils
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from django.db.backends.base.base import BaseDatabaseWrapper
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from django.utils.asyncio import async_unsafe
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from django.utils.functional import cached_property
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from django.utils.regex_helper import _lazy_re_compile
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try:
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import MySQLdb as Database
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except ImportError as err:
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raise ImproperlyConfigured(
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'Error loading MySQLdb module.\n'
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'Did you install mysqlclient?'
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) from err
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from MySQLdb.constants import CLIENT, FIELD_TYPE # isort:skip
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from MySQLdb.converters import conversions # isort:skip
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# Some of these import MySQLdb, so import them after checking if it's installed.
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from .client import DatabaseClient # isort:skip
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from .creation import DatabaseCreation # isort:skip
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from .features import DatabaseFeatures # isort:skip
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from .introspection import DatabaseIntrospection # isort:skip
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from .operations import DatabaseOperations # isort:skip
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from .schema import DatabaseSchemaEditor # isort:skip
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from .validation import DatabaseValidation # isort:skip
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version = Database.version_info
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if version < (1, 4, 0):
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raise ImproperlyConfigured('mysqlclient 1.4.0 or newer is required; you have %s.' % Database.__version__)
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# MySQLdb returns TIME columns as timedelta -- they are more like timedelta in
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# terms of actual behavior as they are signed and include days -- and Django
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# expects time.
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django_conversions = {
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**conversions,
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**{FIELD_TYPE.TIME: backend_utils.typecast_time},
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}
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# This should match the numerical portion of the version numbers (we can treat
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# versions like 5.0.24 and 5.0.24a as the same).
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server_version_re = _lazy_re_compile(r'(\d{1,2})\.(\d{1,2})\.(\d{1,2})')
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class CursorWrapper:
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"""
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A thin wrapper around MySQLdb's normal cursor class that catches particular
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exception instances and reraises them with the correct types.
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Implemented as a wrapper, rather than a subclass, so that it isn't stuck
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to the particular underlying representation returned by Connection.cursor().
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"""
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codes_for_integrityerror = (
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1048, # Column cannot be null
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1690, # BIGINT UNSIGNED value is out of range
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3819, # CHECK constraint is violated
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4025, # CHECK constraint failed
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)
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def __init__(self, cursor):
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self.cursor = cursor
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def execute(self, query, args=None):
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try:
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# args is None means no string interpolation
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return self.cursor.execute(query, args)
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except Database.OperationalError as e:
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# Map some error codes to IntegrityError, since they seem to be
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# misclassified and Django would prefer the more logical place.
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if e.args[0] in self.codes_for_integrityerror:
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raise IntegrityError(*tuple(e.args))
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raise
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def executemany(self, query, args):
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try:
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return self.cursor.executemany(query, args)
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except Database.OperationalError as e:
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# Map some error codes to IntegrityError, since they seem to be
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# misclassified and Django would prefer the more logical place.
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if e.args[0] in self.codes_for_integrityerror:
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raise IntegrityError(*tuple(e.args))
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raise
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def __getattr__(self, attr):
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return getattr(self.cursor, attr)
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def __iter__(self):
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return iter(self.cursor)
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class DatabaseWrapper(BaseDatabaseWrapper):
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vendor = 'mysql'
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# This dictionary maps Field objects to their associated MySQL column
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# types, as strings. Column-type strings can contain format strings; they'll
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# be interpolated against the values of Field.__dict__ before being output.
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# If a column type is set to None, it won't be included in the output.
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data_types = {
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'AutoField': 'integer AUTO_INCREMENT',
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'BigAutoField': 'bigint AUTO_INCREMENT',
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'BinaryField': 'longblob',
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'BooleanField': 'bool',
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'CharField': 'varchar(%(max_length)s)',
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'DateField': 'date',
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'DateTimeField': 'datetime(6)',
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'DecimalField': 'numeric(%(max_digits)s, %(decimal_places)s)',
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'DurationField': 'bigint',
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'FileField': 'varchar(%(max_length)s)',
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'FilePathField': 'varchar(%(max_length)s)',
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'FloatField': 'double precision',
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'IntegerField': 'integer',
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'BigIntegerField': 'bigint',
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'IPAddressField': 'char(15)',
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'GenericIPAddressField': 'char(39)',
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'JSONField': 'json',
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'NullBooleanField': 'bool',
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'OneToOneField': 'integer',
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'PositiveBigIntegerField': 'bigint UNSIGNED',
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'PositiveIntegerField': 'integer UNSIGNED',
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'PositiveSmallIntegerField': 'smallint UNSIGNED',
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'SlugField': 'varchar(%(max_length)s)',
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'SmallAutoField': 'smallint AUTO_INCREMENT',
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'SmallIntegerField': 'smallint',
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'TextField': 'longtext',
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'TimeField': 'time(6)',
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'UUIDField': 'char(32)',
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}
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# For these data types:
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# - MySQL < 8.0.13 and MariaDB < 10.2.1 don't accept default values and
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# implicitly treat them as nullable
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# - all versions of MySQL and MariaDB don't support full width database
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# indexes
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_limited_data_types = (
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'tinyblob', 'blob', 'mediumblob', 'longblob', 'tinytext', 'text',
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'mediumtext', 'longtext', 'json',
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)
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operators = {
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'exact': '= %s',
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'iexact': 'LIKE %s',
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'contains': 'LIKE BINARY %s',
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'icontains': 'LIKE %s',
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'gt': '> %s',
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'gte': '>= %s',
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'lt': '< %s',
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'lte': '<= %s',
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'startswith': 'LIKE BINARY %s',
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'endswith': 'LIKE BINARY %s',
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'istartswith': 'LIKE %s',
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'iendswith': 'LIKE %s',
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}
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# The patterns below are used to generate SQL pattern lookup clauses when
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# the right-hand side of the lookup isn't a raw string (it might be an expression
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# or the result of a bilateral transformation).
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# In those cases, special characters for LIKE operators (e.g. \, *, _) should be
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# escaped on database side.
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#
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# Note: we use str.format() here for readability as '%' is used as a wildcard for
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# the LIKE operator.
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pattern_esc = r"REPLACE(REPLACE(REPLACE({}, '\\', '\\\\'), '%%', '\%%'), '_', '\_')"
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pattern_ops = {
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'contains': "LIKE BINARY CONCAT('%%', {}, '%%')",
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'icontains': "LIKE CONCAT('%%', {}, '%%')",
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'startswith': "LIKE BINARY CONCAT({}, '%%')",
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'istartswith': "LIKE CONCAT({}, '%%')",
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'endswith': "LIKE BINARY CONCAT('%%', {})",
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'iendswith': "LIKE CONCAT('%%', {})",
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}
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isolation_levels = {
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'read uncommitted',
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'read committed',
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'repeatable read',
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'serializable',
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}
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Database = Database
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SchemaEditorClass = DatabaseSchemaEditor
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# Classes instantiated in __init__().
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client_class = DatabaseClient
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creation_class = DatabaseCreation
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features_class = DatabaseFeatures
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introspection_class = DatabaseIntrospection
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ops_class = DatabaseOperations
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validation_class = DatabaseValidation
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def get_connection_params(self):
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kwargs = {
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'conv': django_conversions,
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'charset': 'utf8',
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}
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settings_dict = self.settings_dict
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if settings_dict['USER']:
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kwargs['user'] = settings_dict['USER']
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if settings_dict['NAME']:
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kwargs['db'] = settings_dict['NAME']
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if settings_dict['PASSWORD']:
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kwargs['passwd'] = settings_dict['PASSWORD']
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if settings_dict['HOST'].startswith('/'):
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kwargs['unix_socket'] = settings_dict['HOST']
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elif settings_dict['HOST']:
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kwargs['host'] = settings_dict['HOST']
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if settings_dict['PORT']:
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kwargs['port'] = int(settings_dict['PORT'])
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# We need the number of potentially affected rows after an
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# "UPDATE", not the number of changed rows.
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kwargs['client_flag'] = CLIENT.FOUND_ROWS
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# Validate the transaction isolation level, if specified.
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options = settings_dict['OPTIONS'].copy()
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isolation_level = options.pop('isolation_level', 'read committed')
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if isolation_level:
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isolation_level = isolation_level.lower()
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if isolation_level not in self.isolation_levels:
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raise ImproperlyConfigured(
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"Invalid transaction isolation level '%s' specified.\n"
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"Use one of %s, or None." % (
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isolation_level,
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', '.join("'%s'" % s for s in sorted(self.isolation_levels))
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))
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self.isolation_level = isolation_level
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kwargs.update(options)
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return kwargs
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@async_unsafe
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def get_new_connection(self, conn_params):
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return Database.connect(**conn_params)
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def init_connection_state(self):
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assignments = []
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if self.features.is_sql_auto_is_null_enabled:
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# SQL_AUTO_IS_NULL controls whether an AUTO_INCREMENT column on
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# a recently inserted row will return when the field is tested
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# for NULL. Disabling this brings this aspect of MySQL in line
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# with SQL standards.
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assignments.append('SET SQL_AUTO_IS_NULL = 0')
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if self.isolation_level:
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assignments.append('SET SESSION TRANSACTION ISOLATION LEVEL %s' % self.isolation_level.upper())
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if assignments:
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with self.cursor() as cursor:
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cursor.execute('; '.join(assignments))
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@async_unsafe
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def create_cursor(self, name=None):
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cursor = self.connection.cursor()
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return CursorWrapper(cursor)
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def _rollback(self):
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try:
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BaseDatabaseWrapper._rollback(self)
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except Database.NotSupportedError:
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pass
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def _set_autocommit(self, autocommit):
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with self.wrap_database_errors:
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self.connection.autocommit(autocommit)
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def disable_constraint_checking(self):
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"""
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Disable foreign key checks, primarily for use in adding rows with
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forward references. Always return True to indicate constraint checks
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need to be re-enabled.
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"""
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with self.cursor() as cursor:
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cursor.execute('SET foreign_key_checks=0')
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return True
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def enable_constraint_checking(self):
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"""
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Re-enable foreign key checks after they have been disabled.
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"""
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# Override needs_rollback in case constraint_checks_disabled is
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# nested inside transaction.atomic.
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self.needs_rollback, needs_rollback = False, self.needs_rollback
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try:
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with self.cursor() as cursor:
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cursor.execute('SET foreign_key_checks=1')
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finally:
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self.needs_rollback = needs_rollback
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def check_constraints(self, table_names=None):
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"""
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Check each table name in `table_names` for rows with invalid foreign
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key references. This method is intended to be used in conjunction with
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`disable_constraint_checking()` and `enable_constraint_checking()`, to
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determine if rows with invalid references were entered while constraint
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checks were off.
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"""
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with self.cursor() as cursor:
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if table_names is None:
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table_names = self.introspection.table_names(cursor)
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for table_name in table_names:
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primary_key_column_name = self.introspection.get_primary_key_column(cursor, table_name)
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if not primary_key_column_name:
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continue
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key_columns = self.introspection.get_key_columns(cursor, table_name)
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for column_name, referenced_table_name, referenced_column_name in key_columns:
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cursor.execute(
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"""
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SELECT REFERRING.`%s`, REFERRING.`%s` FROM `%s` as REFERRING
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LEFT JOIN `%s` as REFERRED
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ON (REFERRING.`%s` = REFERRED.`%s`)
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WHERE REFERRING.`%s` IS NOT NULL AND REFERRED.`%s` IS NULL
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""" % (
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primary_key_column_name, column_name, table_name,
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referenced_table_name, column_name, referenced_column_name,
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column_name, referenced_column_name,
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)
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)
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for bad_row in cursor.fetchall():
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raise IntegrityError(
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"The row in table '%s' with primary key '%s' has an invalid "
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"foreign key: %s.%s contains a value '%s' that does not "
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"have a corresponding value in %s.%s."
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% (
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table_name, bad_row[0], table_name, column_name,
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bad_row[1], referenced_table_name, referenced_column_name,
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)
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)
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def is_usable(self):
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try:
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self.connection.ping()
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except Database.Error:
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return False
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else:
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return True
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@cached_property
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def display_name(self):
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return 'MariaDB' if self.mysql_is_mariadb else 'MySQL'
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@cached_property
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def data_type_check_constraints(self):
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if self.features.supports_column_check_constraints:
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check_constraints = {
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'PositiveBigIntegerField': '`%(column)s` >= 0',
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'PositiveIntegerField': '`%(column)s` >= 0',
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'PositiveSmallIntegerField': '`%(column)s` >= 0',
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}
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if self.mysql_is_mariadb and self.mysql_version < (10, 4, 3):
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# MariaDB < 10.4.3 doesn't automatically use the JSON_VALID as
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# a check constraint.
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check_constraints['JSONField'] = 'JSON_VALID(`%(column)s`)'
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return check_constraints
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return {}
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@cached_property
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def mysql_server_info(self):
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with self.temporary_connection() as cursor:
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cursor.execute('SELECT VERSION()')
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return cursor.fetchone()[0]
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@cached_property
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def mysql_version(self):
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match = server_version_re.match(self.mysql_server_info)
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if not match:
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raise Exception('Unable to determine MySQL version from version string %r' % self.mysql_server_info)
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return tuple(int(x) for x in match.groups())
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@cached_property
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def mysql_is_mariadb(self):
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return 'mariadb' in self.mysql_server_info.lower()
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@cached_property
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def sql_mode(self):
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with self.cursor() as cursor:
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cursor.execute('SELECT @@sql_mode')
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sql_mode = cursor.fetchone()
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return set(sql_mode[0].split(',') if sql_mode else ())
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