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"""
MySQL database backend for Django.
Requires mysqlclient: https://pypi.org/project/mysqlclient/
"""
import re
from django.core.exceptions import ImproperlyConfigured
from django.db import utils
from django.db.backends import utils as backend_utils
from django.db.backends.base.base import BaseDatabaseWrapper
from django.utils.functional import cached_property
try:
import MySQLdb as Database
except ImportError as err:
raise ImproperlyConfigured(
'Error loading MySQLdb module.\n'
'Did you install mysqlclient?'
) from err
from MySQLdb.constants import CLIENT, FIELD_TYPE # isort:skip
from MySQLdb.converters import conversions # isort:skip
# Some of these import MySQLdb, so import them after checking if it's installed.
from .client import DatabaseClient # isort:skip
from .creation import DatabaseCreation # isort:skip
from .features import DatabaseFeatures # isort:skip
from .introspection import DatabaseIntrospection # isort:skip
from .operations import DatabaseOperations # isort:skip
from .schema import DatabaseSchemaEditor # isort:skip
from .validation import DatabaseValidation # isort:skip
version = Database.version_info
if version < (1, 3, 13):
raise ImproperlyConfigured('mysqlclient 1.3.13 or newer is required; you have %s.' % Database.__version__)
# MySQLdb returns TIME columns as timedelta -- they are more like timedelta in
# terms of actual behavior as they are signed and include days -- and Django
# expects time.
django_conversions = {
**conversions,
**{FIELD_TYPE.TIME: backend_utils.typecast_time},
}
# This should match the numerical portion of the version numbers (we can treat
# versions like 5.0.24 and 5.0.24a as the same).
server_version_re = re.compile(r'(\d{1,2})\.(\d{1,2})\.(\d{1,2})')
class CursorWrapper:
"""
A thin wrapper around MySQLdb's normal cursor class that catches particular
exception instances and reraises them with the correct types.
Implemented as a wrapper, rather than a subclass, so that it isn't stuck
to the particular underlying representation returned by Connection.cursor().
"""
codes_for_integrityerror = (
1048, # Column cannot be null
1690, # BIGINT UNSIGNED value is out of range
)
def __init__(self, cursor):
self.cursor = cursor
def execute(self, query, args=None):
try:
# args is None means no string interpolation
return self.cursor.execute(query, args)
except Database.OperationalError as e:
# Map some error codes to IntegrityError, since they seem to be
# misclassified and Django would prefer the more logical place.
if e.args[0] in self.codes_for_integrityerror:
raise utils.IntegrityError(*tuple(e.args))
raise
def executemany(self, query, args):
try:
return self.cursor.executemany(query, args)
except Database.OperationalError as e:
# Map some error codes to IntegrityError, since they seem to be
# misclassified and Django would prefer the more logical place.
if e.args[0] in self.codes_for_integrityerror:
raise utils.IntegrityError(*tuple(e.args))
raise
def __getattr__(self, attr):
return getattr(self.cursor, attr)
def __iter__(self):
return iter(self.cursor)
class DatabaseWrapper(BaseDatabaseWrapper):
vendor = 'mysql'
display_name = 'MySQL'
# This dictionary maps Field objects to their associated MySQL column
# types, as strings. Column-type strings can contain format strings; they'll
# be interpolated against the values of Field.__dict__ before being output.
# If a column type is set to None, it won't be included in the output.
data_types = {
'AutoField': 'integer AUTO_INCREMENT',
'BigAutoField': 'bigint AUTO_INCREMENT',
'BinaryField': 'longblob',
'BooleanField': 'bool',
'CharField': 'varchar(%(max_length)s)',
'DateField': 'date',
'DateTimeField': 'datetime(6)',
'DecimalField': 'numeric(%(max_digits)s, %(decimal_places)s)',
'DurationField': 'bigint',
'FileField': 'varchar(%(max_length)s)',
'FilePathField': 'varchar(%(max_length)s)',
'FloatField': 'double precision',
'IntegerField': 'integer',
'BigIntegerField': 'bigint',
'IPAddressField': 'char(15)',
'GenericIPAddressField': 'char(39)',
'NullBooleanField': 'bool',
'OneToOneField': 'integer',
'PositiveIntegerField': 'integer UNSIGNED',
'PositiveSmallIntegerField': 'smallint UNSIGNED',
'SlugField': 'varchar(%(max_length)s)',
'SmallIntegerField': 'smallint',
'TextField': 'longtext',
'TimeField': 'time(6)',
'UUIDField': 'char(32)',
}
# For these columns, MySQL doesn't:
# - accept default values and implicitly treats these columns as nullable
# - support a database index
_limited_data_types = (
'tinyblob', 'blob', 'mediumblob', 'longblob', 'tinytext', 'text',
'mediumtext', 'longtext', 'json',
)
operators = {
'exact': '= %s',
'iexact': 'LIKE %s',
'contains': 'LIKE BINARY %s',
'icontains': 'LIKE %s',
'gt': '> %s',
'gte': '>= %s',
'lt': '< %s',
'lte': '<= %s',
'startswith': 'LIKE BINARY %s',
'endswith': 'LIKE BINARY %s',
'istartswith': 'LIKE %s',
'iendswith': 'LIKE %s',
}
# The patterns below are used to generate SQL pattern lookup clauses when
# the right-hand side of the lookup isn't a raw string (it might be an expression
# or the result of a bilateral transformation).
# In those cases, special characters for LIKE operators (e.g. \, *, _) should be
# escaped on database side.
#
# Note: we use str.format() here for readability as '%' is used as a wildcard for
# the LIKE operator.
pattern_esc = r"REPLACE(REPLACE(REPLACE({}, '\\', '\\\\'), '%%', '\%%'), '_', '\_')"
pattern_ops = {
'contains': "LIKE BINARY CONCAT('%%', {}, '%%')",
'icontains': "LIKE CONCAT('%%', {}, '%%')",
'startswith': "LIKE BINARY CONCAT({}, '%%')",
'istartswith': "LIKE CONCAT({}, '%%')",
'endswith': "LIKE BINARY CONCAT('%%', {})",
'iendswith': "LIKE CONCAT('%%', {})",
}
isolation_levels = {
'read uncommitted',
'read committed',
'repeatable read',
'serializable',
}
Database = Database
SchemaEditorClass = DatabaseSchemaEditor
# Classes instantiated in __init__().
client_class = DatabaseClient
creation_class = DatabaseCreation
features_class = DatabaseFeatures
introspection_class = DatabaseIntrospection
ops_class = DatabaseOperations
validation_class = DatabaseValidation
def get_connection_params(self):
kwargs = {
'conv': django_conversions,
'charset': 'utf8',
}
settings_dict = self.settings_dict
if settings_dict['USER']:
kwargs['user'] = settings_dict['USER']
if settings_dict['NAME']:
kwargs['db'] = settings_dict['NAME']
if settings_dict['PASSWORD']:
kwargs['passwd'] = settings_dict['PASSWORD']
if settings_dict['HOST'].startswith('/'):
kwargs['unix_socket'] = settings_dict['HOST']
elif settings_dict['HOST']:
kwargs['host'] = settings_dict['HOST']
if settings_dict['PORT']:
kwargs['port'] = int(settings_dict['PORT'])
# We need the number of potentially affected rows after an
# "UPDATE", not the number of changed rows.
kwargs['client_flag'] = CLIENT.FOUND_ROWS
# Validate the transaction isolation level, if specified.
options = settings_dict['OPTIONS'].copy()
isolation_level = options.pop('isolation_level', 'read committed')
if isolation_level:
isolation_level = isolation_level.lower()
if isolation_level not in self.isolation_levels:
raise ImproperlyConfigured(
"Invalid transaction isolation level '%s' specified.\n"
"Use one of %s, or None." % (
isolation_level,
', '.join("'%s'" % s for s in sorted(self.isolation_levels))
))
self.isolation_level = isolation_level
kwargs.update(options)
return kwargs
def get_new_connection(self, conn_params):
return Database.connect(**conn_params)
def init_connection_state(self):
assignments = []
if self.features.is_sql_auto_is_null_enabled:
# SQL_AUTO_IS_NULL controls whether an AUTO_INCREMENT column on
# a recently inserted row will return when the field is tested
# for NULL. Disabling this brings this aspect of MySQL in line
# with SQL standards.
assignments.append('SET SQL_AUTO_IS_NULL = 0')
if self.isolation_level:
assignments.append('SET SESSION TRANSACTION ISOLATION LEVEL %s' % self.isolation_level.upper())
if assignments:
with self.cursor() as cursor:
cursor.execute('; '.join(assignments))
def create_cursor(self, name=None):
cursor = self.connection.cursor()
return CursorWrapper(cursor)
def _rollback(self):
try:
BaseDatabaseWrapper._rollback(self)
except Database.NotSupportedError:
pass
def _set_autocommit(self, autocommit):
with self.wrap_database_errors:
self.connection.autocommit(autocommit)
def disable_constraint_checking(self):
"""
Disable foreign key checks, primarily for use in adding rows with
forward references. Always return True to indicate constraint checks
need to be re-enabled.
"""
self.cursor().execute('SET foreign_key_checks=0')
return True
def enable_constraint_checking(self):
"""
Re-enable foreign key checks after they have been disabled.
"""
# Override needs_rollback in case constraint_checks_disabled is
# nested inside transaction.atomic.
self.needs_rollback, needs_rollback = False, self.needs_rollback
try:
self.cursor().execute('SET foreign_key_checks=1')
finally:
self.needs_rollback = needs_rollback
def check_constraints(self, table_names=None):
"""
Check each table name in `table_names` for rows with invalid foreign
key references. This method is intended to be used in conjunction with
`disable_constraint_checking()` and `enable_constraint_checking()`, to
determine if rows with invalid references were entered while constraint
checks were off.
"""
with self.cursor() as cursor:
if table_names is None:
table_names = self.introspection.table_names(cursor)
for table_name in table_names:
primary_key_column_name = self.introspection.get_primary_key_column(cursor, table_name)
if not primary_key_column_name:
continue
key_columns = self.introspection.get_key_columns(cursor, table_name)
for column_name, referenced_table_name, referenced_column_name in key_columns:
cursor.execute(
"""
SELECT REFERRING.`%s`, REFERRING.`%s` FROM `%s` as REFERRING
LEFT JOIN `%s` as REFERRED
ON (REFERRING.`%s` = REFERRED.`%s`)
WHERE REFERRING.`%s` IS NOT NULL AND REFERRED.`%s` IS NULL
""" % (
primary_key_column_name, column_name, table_name,
referenced_table_name, column_name, referenced_column_name,
column_name, referenced_column_name,
)
)
for bad_row in cursor.fetchall():
raise utils.IntegrityError(
"The row in table '%s' with primary key '%s' has an invalid "
"foreign key: %s.%s contains a value '%s' that does not "
"have a corresponding value in %s.%s."
% (
table_name, bad_row[0], table_name, column_name,
bad_row[1], referenced_table_name, referenced_column_name,
)
)
def is_usable(self):
try:
self.connection.ping()
except Database.Error:
return False
else:
return True
@cached_property
def mysql_server_info(self):
with self.temporary_connection() as cursor:
cursor.execute('SELECT VERSION()')
return cursor.fetchone()[0]
@cached_property
def mysql_version(self):
match = server_version_re.match(self.mysql_server_info)
if not match:
raise Exception('Unable to determine MySQL version from version string %r' % self.mysql_server_info)
return tuple(int(x) for x in match.groups())
@cached_property
def mysql_is_mariadb(self):
# MariaDB isn't officially supported.
return 'mariadb' in self.mysql_server_info.lower()