""" SQLite3 backend for django. Works with either the pysqlite2 module or the sqlite3 module in the standard library. """ from __future__ import unicode_literals import datetime import decimal import warnings import re from django.conf import settings from django.db import utils from django.db.backends import (utils as backend_utils, BaseDatabaseFeatures, BaseDatabaseOperations, BaseDatabaseWrapper, BaseDatabaseValidation) from django.db.backends.sqlite3.client import DatabaseClient from django.db.backends.sqlite3.creation import DatabaseCreation from django.db.backends.sqlite3.introspection import DatabaseIntrospection from django.db.backends.sqlite3.schema import DatabaseSchemaEditor from django.db.models import fields from django.db.models.sql import aggregates from django.utils.dateparse import parse_date, parse_datetime, parse_time from django.utils.encoding import force_text from django.utils.functional import cached_property from django.utils.safestring import SafeBytes from django.utils import six from django.utils import timezone try: try: from pysqlite2 import dbapi2 as Database except ImportError: from sqlite3 import dbapi2 as Database except ImportError as exc: from django.core.exceptions import ImproperlyConfigured raise ImproperlyConfigured("Error loading either pysqlite2 or sqlite3 modules (tried in that order): %s" % exc) try: import pytz except ImportError: pytz = None DatabaseError = Database.DatabaseError IntegrityError = Database.IntegrityError def parse_datetime_with_timezone_support(value): dt = parse_datetime(value) # Confirm that dt is naive before overwriting its tzinfo. if dt is not None and settings.USE_TZ and timezone.is_naive(dt): dt = dt.replace(tzinfo=timezone.utc) return dt def adapt_datetime_with_timezone_support(value): # Equivalent to DateTimeField.get_db_prep_value. Used only by raw SQL. if settings.USE_TZ: if timezone.is_naive(value): warnings.warn("SQLite received a naive datetime (%s)" " while time zone support is active." % value, RuntimeWarning) default_timezone = timezone.get_default_timezone() value = timezone.make_aware(value, default_timezone) value = value.astimezone(timezone.utc).replace(tzinfo=None) return value.isoformat(str(" ")) def decoder(conv_func): """ The Python sqlite3 interface returns always byte strings. This function converts the received value to a regular string before passing it to the receiver function. """ return lambda s: conv_func(s.decode('utf-8')) Database.register_converter(str("bool"), decoder(lambda s: s == '1')) Database.register_converter(str("time"), decoder(parse_time)) Database.register_converter(str("date"), decoder(parse_date)) Database.register_converter(str("datetime"), decoder(parse_datetime_with_timezone_support)) Database.register_converter(str("timestamp"), decoder(parse_datetime_with_timezone_support)) Database.register_converter(str("TIMESTAMP"), decoder(parse_datetime_with_timezone_support)) Database.register_converter(str("decimal"), decoder(backend_utils.typecast_decimal)) Database.register_adapter(datetime.datetime, adapt_datetime_with_timezone_support) Database.register_adapter(decimal.Decimal, backend_utils.rev_typecast_decimal) if six.PY2: Database.register_adapter(str, lambda s: s.decode('utf-8')) Database.register_adapter(SafeBytes, lambda s: s.decode('utf-8')) class DatabaseFeatures(BaseDatabaseFeatures): # SQLite cannot handle us only partially reading from a cursor's result set # and then writing the same rows to the database in another cursor. This # setting ensures we always read result sets fully into memory all in one # go. can_use_chunked_reads = False test_db_allows_multiple_connections = False supports_unspecified_pk = True supports_timezones = False supports_1000_query_parameters = False supports_mixed_date_datetime_comparisons = False has_bulk_insert = True can_combine_inserts_with_and_without_auto_increment_pk = False supports_foreign_keys = False supports_check_constraints = False autocommits_when_autocommit_is_off = True atomic_transactions = False supports_paramstyle_pyformat = False supports_sequence_reset = False @cached_property def uses_savepoints(self): return Database.sqlite_version_info >= (3, 6, 8) @cached_property def supports_stddev(self): """Confirm support for STDDEV and related stats functions SQLite supports STDDEV as an extension package; so connection.ops.check_aggregate_support() can't unilaterally rule out support for STDDEV. We need to manually check whether the call works. """ cursor = self.connection.cursor() cursor.execute('CREATE TABLE STDDEV_TEST (X INT)') try: cursor.execute('SELECT STDDEV(*) FROM STDDEV_TEST') has_support = True except utils.DatabaseError: has_support = False cursor.execute('DROP TABLE STDDEV_TEST') return has_support @cached_property def has_zoneinfo_database(self): return pytz is not None class DatabaseOperations(BaseDatabaseOperations): def bulk_batch_size(self, fields, objs): """ SQLite has a compile-time default (SQLITE_LIMIT_VARIABLE_NUMBER) of 999 variables per query. If there is just single field to insert, then we can hit another limit, SQLITE_MAX_COMPOUND_SELECT which defaults to 500. """ limit = 999 if len(fields) > 1 else 500 return (limit // len(fields)) if len(fields) > 0 else len(objs) def check_aggregate_support(self, aggregate): bad_fields = (fields.DateField, fields.DateTimeField, fields.TimeField) bad_aggregates = (aggregates.Sum, aggregates.Avg, aggregates.Variance, aggregates.StdDev) if (isinstance(aggregate.source, bad_fields) and isinstance(aggregate, bad_aggregates)): raise NotImplementedError( 'You cannot use Sum, Avg, StdDev and Variance aggregations ' 'on date/time fields in sqlite3 ' 'since date/time is saved as text.') def date_extract_sql(self, lookup_type, field_name): # sqlite doesn't support extract, so we fake it with the user-defined # function django_date_extract that's registered in connect(). Note that # single quotes are used because this is a string (and could otherwise # cause a collision with a field name). return "django_date_extract('%s', %s)" % (lookup_type.lower(), field_name) def date_interval_sql(self, sql, connector, timedelta): # It would be more straightforward if we could use the sqlite strftime # function, but it does not allow for keeping six digits of fractional # second information, nor does it allow for formatting date and datetime # values differently. So instead we register our own function that # formats the datetime combined with the delta in a manner suitable # for comparisons. return 'django_format_dtdelta(%s, "%s", "%d", "%d", "%d")' % (sql, connector, timedelta.days, timedelta.seconds, timedelta.microseconds) def date_trunc_sql(self, lookup_type, field_name): # sqlite doesn't support DATE_TRUNC, so we fake it with a user-defined # function django_date_trunc that's registered in connect(). Note that # single quotes are used because this is a string (and could otherwise # cause a collision with a field name). return "django_date_trunc('%s', %s)" % (lookup_type.lower(), field_name) def datetime_extract_sql(self, lookup_type, field_name, tzname): # Same comment as in date_extract_sql. if settings.USE_TZ: if pytz is None: from django.core.exceptions import ImproperlyConfigured raise ImproperlyConfigured("This query requires pytz, " "but it isn't installed.") return "django_datetime_extract('%s', %s, %%s)" % ( lookup_type.lower(), field_name), [tzname] def datetime_trunc_sql(self, lookup_type, field_name, tzname): # Same comment as in date_trunc_sql. if settings.USE_TZ: if pytz is None: from django.core.exceptions import ImproperlyConfigured raise ImproperlyConfigured("This query requires pytz, " "but it isn't installed.") return "django_datetime_trunc('%s', %s, %%s)" % ( lookup_type.lower(), field_name), [tzname] def drop_foreignkey_sql(self): return "" def pk_default_value(self): return "NULL" def quote_name(self, name): if name.startswith('"') and name.endswith('"'): return name # Quoting once is enough. return '"%s"' % name def quote_parameter(self, value): # Inner import to allow nice failure for backend if not present import _sqlite3 try: value = _sqlite3.adapt(value) except _sqlite3.ProgrammingError: pass # Manual emulation of SQLite parameter quoting if isinstance(value, six.integer_types): return str(value) elif isinstance(value, six.string_types): return six.text_type(value) elif isinstance(value, type(True)): return str(int(value)) elif value is None: return "NULL" else: raise ValueError("Cannot quote parameter value %r" % value) def no_limit_value(self): return -1 def sql_flush(self, style, tables, sequences, allow_cascade=False): # NB: The generated SQL below is specific to SQLite # Note: The DELETE FROM... SQL generated below works for SQLite databases # because constraints don't exist sql = ['%s %s %s;' % ( style.SQL_KEYWORD('DELETE'), style.SQL_KEYWORD('FROM'), style.SQL_FIELD(self.quote_name(table)) ) for table in tables] # Note: No requirement for reset of auto-incremented indices (cf. other # sql_flush() implementations). Just return SQL at this point return sql def value_to_db_datetime(self, value): if value is None: return None # SQLite doesn't support tz-aware datetimes if timezone.is_aware(value): if settings.USE_TZ: value = value.astimezone(timezone.utc).replace(tzinfo=None) else: raise ValueError("SQLite backend does not support timezone-aware datetimes when USE_TZ is False.") return six.text_type(value) def value_to_db_time(self, value): if value is None: return None # SQLite doesn't support tz-aware datetimes if timezone.is_aware(value): raise ValueError("SQLite backend does not support timezone-aware times.") return six.text_type(value) def convert_values(self, value, field): """SQLite returns floats when it should be returning decimals, and gets dates and datetimes wrong. For consistency with other backends, coerce when required. """ if value is None: return None internal_type = field.get_internal_type() if internal_type == 'DecimalField': return backend_utils.typecast_decimal(field.format_number(value)) elif internal_type and internal_type.endswith('IntegerField') or internal_type == 'AutoField': return int(value) elif internal_type == 'DateField': return parse_date(value) elif internal_type == 'DateTimeField': return parse_datetime_with_timezone_support(value) elif internal_type == 'TimeField': return parse_time(value) # No field, or the field isn't known to be a decimal or integer return value def bulk_insert_sql(self, fields, num_values): res = [] res.append("SELECT %s" % ", ".join( "%%s AS %s" % self.quote_name(f.column) for f in fields )) res.extend(["UNION ALL SELECT %s" % ", ".join(["%s"] * len(fields))] * (num_values - 1)) return " ".join(res) class DatabaseWrapper(BaseDatabaseWrapper): vendor = 'sqlite' # SQLite requires LIKE statements to include an ESCAPE clause if the value # being escaped has a percent or underscore in it. # See http://www.sqlite.org/lang_expr.html for an explanation. operators = { 'exact': '= %s', 'iexact': "LIKE %s ESCAPE '\\'", 'contains': "LIKE %s ESCAPE '\\'", 'icontains': "LIKE %s ESCAPE '\\'", 'regex': 'REGEXP %s', 'iregex': "REGEXP '(?i)' || %s", 'gt': '> %s', 'gte': '>= %s', 'lt': '< %s', 'lte': '<= %s', 'startswith': "LIKE %s ESCAPE '\\'", 'endswith': "LIKE %s ESCAPE '\\'", 'istartswith': "LIKE %s ESCAPE '\\'", 'iendswith': "LIKE %s ESCAPE '\\'", } Database = Database def __init__(self, *args, **kwargs): super(DatabaseWrapper, self).__init__(*args, **kwargs) self.features = DatabaseFeatures(self) self.ops = DatabaseOperations(self) self.client = DatabaseClient(self) self.creation = DatabaseCreation(self) self.introspection = DatabaseIntrospection(self) self.validation = BaseDatabaseValidation(self) def get_connection_params(self): settings_dict = self.settings_dict if not settings_dict['NAME']: from django.core.exceptions import ImproperlyConfigured raise ImproperlyConfigured( "settings.DATABASES is improperly configured. " "Please supply the NAME value.") kwargs = { 'database': settings_dict['NAME'], 'detect_types': Database.PARSE_DECLTYPES | Database.PARSE_COLNAMES, } kwargs.update(settings_dict['OPTIONS']) # Always allow the underlying SQLite connection to be shareable # between multiple threads. The safe-guarding will be handled at a # higher level by the `BaseDatabaseWrapper.allow_thread_sharing` # property. This is necessary as the shareability is disabled by # default in pysqlite and it cannot be changed once a connection is # opened. if 'check_same_thread' in kwargs and kwargs['check_same_thread']: warnings.warn( 'The `check_same_thread` option was provided and set to ' 'True. It will be overridden with False. Use the ' '`DatabaseWrapper.allow_thread_sharing` property instead ' 'for controlling thread shareability.', RuntimeWarning ) kwargs.update({'check_same_thread': False}) return kwargs def get_new_connection(self, conn_params): conn = Database.connect(**conn_params) conn.create_function("django_date_extract", 2, _sqlite_date_extract) conn.create_function("django_date_trunc", 2, _sqlite_date_trunc) conn.create_function("django_datetime_extract", 3, _sqlite_datetime_extract) conn.create_function("django_datetime_trunc", 3, _sqlite_datetime_trunc) conn.create_function("regexp", 2, _sqlite_regexp) conn.create_function("django_format_dtdelta", 5, _sqlite_format_dtdelta) return conn def init_connection_state(self): pass def create_cursor(self): return self.connection.cursor(factory=SQLiteCursorWrapper) def close(self): self.validate_thread_sharing() # If database is in memory, closing the connection destroys the # database. To prevent accidental data loss, ignore close requests on # an in-memory db. if self.settings_dict['NAME'] != ":memory:": BaseDatabaseWrapper.close(self) def _savepoint_allowed(self): # When 'isolation_level' is not None, sqlite3 commits before each # savepoint; it's a bug. When it is None, savepoints don't make sense # because autocommit is enabled. The only exception is inside atomic # blocks. To work around that bug, on SQLite, atomic starts a # transaction explicitly rather than simply disable autocommit. return self.in_atomic_block def _set_autocommit(self, autocommit): if autocommit: level = None else: # sqlite3's internal default is ''. It's different from None. # See Modules/_sqlite/connection.c. level = '' # 'isolation_level' is a misleading API. # SQLite always runs at the SERIALIZABLE isolation level. self.connection.isolation_level = level def check_constraints(self, table_names=None): """ Checks 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. Raises an IntegrityError on the first invalid foreign key reference encountered (if any) and provides detailed information about the invalid reference in the error message. Backends can override this method if they can more directly apply constraint checking (e.g. via "SET CONSTRAINTS ALL IMMEDIATE") """ cursor = self.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): return True def _start_transaction_under_autocommit(self): """ Start a transaction explicitly in autocommit mode. Staying in autocommit mode works around a bug of sqlite3 that breaks savepoints when autocommit is disabled. """ self.cursor().execute("BEGIN") def schema_editor(self, *args, **kwargs): "Returns a new instance of this backend's SchemaEditor" return DatabaseSchemaEditor(self, *args, **kwargs) FORMAT_QMARK_REGEX = re.compile(r'(?