345 lines
14 KiB
Python
345 lines
14 KiB
Python
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"""
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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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import re
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from django.core.exceptions import ImproperlyConfigured
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from django.db import utils
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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.functional import cached_property
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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, 3, 7):
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raise ImproperlyConfigured('mysqlclient 1.3.7 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 = 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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)
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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 utils.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 utils.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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display_name = '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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'NullBooleanField': 'bool',
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'OneToOneField': 'integer',
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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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'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 columns, MySQL doesn't:
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# - accept default values and implicitly treats these columns as nullable
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# - support a database index
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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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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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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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self.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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self.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 utils.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 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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# MariaDB isn't officially supported.
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return 'mariadb' in self.mysql_server_info.lower()
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