445 lines
16 KiB
Python
445 lines
16 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.\nDid you install mysqlclient?"
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) from err
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from MySQLdb.constants import CLIENT, FIELD_TYPE
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from MySQLdb.converters import conversions
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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
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from .creation import DatabaseCreation
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from .features import DatabaseFeatures
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from .introspection import DatabaseIntrospection
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from .operations import DatabaseOperations
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from .schema import DatabaseSchemaEditor
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from .validation import DatabaseValidation
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version = Database.version_info
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if version < (1, 4, 3):
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raise ImproperlyConfigured(
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"mysqlclient 1.4.3 or newer is required; you have %s." % Database.__version__
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)
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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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"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 doesn't accept default values and implicitly treats them
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# 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",
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"blob",
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"mediumblob",
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"longblob",
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"tinytext",
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"text",
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"mediumtext",
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"longtext",
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"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_database_version(self):
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return self.mysql_version
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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["database"] = settings_dict["NAME"]
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if settings_dict["PASSWORD"]:
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kwargs["password"] = 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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% (
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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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)
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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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connection = Database.connect(**conn_params)
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# bytes encoder in mysqlclient doesn't work and was added only to
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# prevent KeyErrors in Django < 2.0. We can remove this workaround when
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# mysqlclient 2.1 becomes the minimal mysqlclient supported by Django.
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# See https://github.com/PyMySQL/mysqlclient/issues/489
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if connection.encoders.get(bytes) is bytes:
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connection.encoders.pop(bytes)
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return connection
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def init_connection_state(self):
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super().init_connection_state()
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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(
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"SET SESSION TRANSACTION ISOLATION LEVEL %s"
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% self.isolation_level.upper()
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)
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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(
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cursor, table_name
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)
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if not primary_key_column_name:
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continue
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relations = self.introspection.get_relations(cursor, table_name)
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for column_name, (
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referenced_column_name,
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referenced_table_name,
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) in relations.items():
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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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% (
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primary_key_column_name,
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column_name,
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table_name,
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referenced_table_name,
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column_name,
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referenced_column_name,
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column_name,
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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 "
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"invalid foreign key: %s.%s contains a value '%s' that "
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"does not have a corresponding value in %s.%s."
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% (
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table_name,
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bad_row[0],
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table_name,
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column_name,
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bad_row[1],
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referenced_table_name,
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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_data(self):
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with self.temporary_connection() as cursor:
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# Select some server variables and test if the time zone
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# definitions are installed. CONVERT_TZ returns NULL if 'UTC'
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# timezone isn't loaded into the mysql.time_zone table.
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cursor.execute(
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"""
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SELECT VERSION(),
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@@sql_mode,
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@@default_storage_engine,
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@@sql_auto_is_null,
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@@lower_case_table_names,
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CONVERT_TZ('2001-01-01 01:00:00', 'UTC', 'UTC') IS NOT NULL
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"""
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)
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row = cursor.fetchone()
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return {
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"version": row[0],
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"sql_mode": row[1],
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"default_storage_engine": row[2],
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"sql_auto_is_null": bool(row[3]),
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"lower_case_table_names": bool(row[4]),
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"has_zoneinfo_database": bool(row[5]),
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}
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@cached_property
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def mysql_server_info(self):
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return self.mysql_server_data["version"]
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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(
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"Unable to determine MySQL version from version string %r"
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% self.mysql_server_info
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)
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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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sql_mode = self.mysql_server_data["sql_mode"]
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return set(sql_mode.split(",") if sql_mode else ())
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