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Jan Broer
2015-08-02 20:59:11 +02:00
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lib/sqlalchemy/dialects/sqlite/__init__.py Normal file
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# sqlite/__init__.py
# Copyright (C) 2005-2013 the SQLAlchemy authors and contributors <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
from sqlalchemy.dialects.sqlite import base, pysqlite
# default dialect
base.dialect = pysqlite.dialect
from sqlalchemy.dialects.sqlite.base import \
BLOB, BOOLEAN, CHAR, DATE, DATETIME, DECIMAL, FLOAT, INTEGER, REAL,\
NUMERIC, SMALLINT, TEXT, TIME, TIMESTAMP, VARCHAR, dialect
__all__ = (
'BLOB', 'BOOLEAN', 'CHAR', 'DATE', 'DATETIME', 'DECIMAL', 'FLOAT',
'INTEGER', 'NUMERIC', 'SMALLINT', 'TEXT', 'TIME', 'TIMESTAMP', 'VARCHAR',
'REAL', 'dialect'
)

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lib/sqlalchemy/dialects/sqlite/base.py Normal file
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# sqlite/base.py
# Copyright (C) 2005-2013 the SQLAlchemy authors and contributors <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""
.. dialect:: sqlite
:name: SQLite
Date and Time Types
-------------------
SQLite does not have built-in DATE, TIME, or DATETIME types, and pysqlite
does not provide out of the box functionality for translating values between
Python `datetime` objects and a SQLite-supported format. SQLAlchemy's own
:class:`~sqlalchemy.types.DateTime` and related types provide date formatting
and parsing functionality when SQlite is used. The implementation classes are
:class:`~.sqlite.DATETIME`, :class:`~.sqlite.DATE` and :class:`~.sqlite.TIME`.
These types represent dates and times as ISO formatted strings, which also
nicely support ordering. There's no reliance on typical "libc" internals
for these functions so historical dates are fully supported.
Auto Incrementing Behavior
--------------------------
Background on SQLite's autoincrement is at: http://sqlite.org/autoinc.html
Two things to note:
* The AUTOINCREMENT keyword is **not** required for SQLite tables to
generate primary key values automatically. AUTOINCREMENT only means that
the algorithm used to generate ROWID values should be slightly different.
* SQLite does **not** generate primary key (i.e. ROWID) values, even for
one column, if the table has a composite (i.e. multi-column) primary key.
This is regardless of the AUTOINCREMENT keyword being present or not.
To specifically render the AUTOINCREMENT keyword on the primary key
column when rendering DDL, add the flag ``sqlite_autoincrement=True``
to the Table construct::
Table('sometable', metadata,
Column('id', Integer, primary_key=True),
sqlite_autoincrement=True)
Transaction Isolation Level
---------------------------
:func:`.create_engine` accepts an ``isolation_level`` parameter which
results in the command ``PRAGMA read_uncommitted <level>`` being invoked for
every new connection. Valid values for this parameter are ``SERIALIZABLE``
and ``READ UNCOMMITTED`` corresponding to a value of 0 and 1, respectively.
See the section :ref:`pysqlite_serializable` for an important workaround
when using serializable isolation with Pysqlite.
Database Locking Behavior / Concurrency
---------------------------------------
Note that SQLite is not designed for a high level of concurrency. The
database itself, being a file, is locked completely during write operations
and within transactions, meaning exactly one connection has exclusive access
to the database during this period - all other connections will be blocked
during this time.
The Python DBAPI specification also calls for a connection model that is always
in a transaction; there is no BEGIN method, only commit and rollback. This
implies that a SQLite DBAPI driver would technically allow only serialized
access to a particular database file at all times. The pysqlite driver
attempts to ameliorate this by deferring the actual BEGIN statement until
the first DML (INSERT, UPDATE, or DELETE) is received within a
transaction. While this breaks serializable isolation, it at least delays
the exclusive locking inherent in SQLite's design.
SQLAlchemy's default mode of usage with the ORM is known
as "autocommit=False", which means the moment the :class:`.Session` begins to
be used, a transaction is begun. As the :class:`.Session` is used, the
autoflush feature, also on by default, will flush out pending changes to the
database before each query. The effect of this is that a :class:`.Session`
used in its default mode will often emit DML early on, long before the
transaction is actually committed. This again will have the effect of
serializing access to the SQLite database. If highly concurrent reads are
desired against the SQLite database, it is advised that the autoflush feature
be disabled, and potentially even that autocommit be re-enabled, which has
the effect of each SQL statement and flush committing changes immediately.
For more information on SQLite's lack of concurrency by design, please
see `Situations Where Another RDBMS May Work Better - High
Concurrency <http://www.sqlite.org/whentouse.html>`_ near the bottom of
the page.
.. _sqlite_foreign_keys:
Foreign Key Support
-------------------
SQLite supports FOREIGN KEY syntax when emitting CREATE statements for tables,
however by default these constraints have no effect on the operation
of the table.
Constraint checking on SQLite has three prerequisites:
* At least version 3.6.19 of SQLite must be in use
* The SQLite libary must be compiled *without* the SQLITE_OMIT_FOREIGN_KEY
or SQLITE_OMIT_TRIGGER symbols enabled.
* The ``PRAGMA foreign_keys = ON`` statement must be emitted on all connections
before use.
SQLAlchemy allows for the ``PRAGMA`` statement to be emitted automatically
for new connections through the usage of events::
from sqlalchemy.engine import Engine
from sqlalchemy import event
@event.listens_for(Engine, "connect")
def set_sqlite_pragma(dbapi_connection, connection_record):
cursor = dbapi_connection.cursor()
cursor.execute("PRAGMA foreign_keys=ON")
cursor.close()
.. seealso::
`SQLite Foreign Key Support <http://www.sqlite.org/foreignkeys.html>`_ -
on the SQLite web site.
:ref:`event_toplevel` - SQLAlchemy event API.
"""
import datetime
import re
from sqlalchemy import sql, exc
from sqlalchemy.engine import default, base, reflection
from sqlalchemy import types as sqltypes
from sqlalchemy import util
from sqlalchemy.sql import compiler
from sqlalchemy import processors
from sqlalchemy.types import BIGINT, BLOB, BOOLEAN, CHAR,\
DECIMAL, FLOAT, REAL, INTEGER, NUMERIC, SMALLINT, TEXT,\
TIMESTAMP, VARCHAR
class _DateTimeMixin(object):
_reg = None
_storage_format = None
def __init__(self, storage_format=None, regexp=None, **kw):
super(_DateTimeMixin, self).__init__(**kw)
if regexp is not None:
self._reg = re.compile(regexp)
if storage_format is not None:
self._storage_format = storage_format
def adapt(self, cls, **kw):
if self._storage_format:
kw["storage_format"] = self._storage_format
if self._reg:
kw["regexp"] = self._reg
return util.constructor_copy(self, cls, **kw)
class DATETIME(_DateTimeMixin, sqltypes.DateTime):
"""Represent a Python datetime object in SQLite using a string.
The default string storage format is::
"%(year)04d-%(month)02d-%(day)02d %(hour)02d:%(min)02d:%(second)02d.%(microsecond)06d"
e.g.::
2011-03-15 12:05:57.10558
The storage format can be customized to some degree using the
``storage_format`` and ``regexp`` parameters, such as::
import re
from sqlalchemy.dialects.sqlite import DATETIME
dt = DATETIME(
storage_format="%(year)04d/%(month)02d/%(day)02d %(hour)02d:%(min)02d:%(second)02d",
regexp=r"(\d+)/(\d+)/(\d+) (\d+)-(\d+)-(\d+)"
)
:param storage_format: format string which will be applied to the
dict with keys year, month, day, hour, minute, second, and microsecond.
:param regexp: regular expression which will be applied to
incoming result rows. If the regexp contains named groups, the
resulting match dict is applied to the Python datetime() constructor
as keyword arguments. Otherwise, if positional groups are used, the
the datetime() constructor is called with positional arguments via
``*map(int, match_obj.groups(0))``.
"""
_storage_format = (
"%(year)04d-%(month)02d-%(day)02d "
"%(hour)02d:%(minute)02d:%(second)02d.%(microsecond)06d"
)
def __init__(self, *args, **kwargs):
truncate_microseconds = kwargs.pop('truncate_microseconds', False)
super(DATETIME, self).__init__(*args, **kwargs)
if truncate_microseconds:
assert 'storage_format' not in kwargs, "You can specify only "\
"one of truncate_microseconds or storage_format."
assert 'regexp' not in kwargs, "You can specify only one of "\
"truncate_microseconds or regexp."
self._storage_format = (
"%(year)04d-%(month)02d-%(day)02d "
"%(hour)02d:%(minute)02d:%(second)02d"
)
def bind_processor(self, dialect):
datetime_datetime = datetime.datetime
datetime_date = datetime.date
format = self._storage_format
def process(value):
if value is None:
return None
elif isinstance(value, datetime_datetime):
return format % {
'year': value.year,
'month': value.month,
'day': value.day,
'hour': value.hour,
'minute': value.minute,
'second': value.second,
'microsecond': value.microsecond,
}
elif isinstance(value, datetime_date):
return format % {
'year': value.year,
'month': value.month,
'day': value.day,
'hour': 0,
'minute': 0,
'second': 0,
'microsecond': 0,
}
else:
raise TypeError("SQLite DateTime type only accepts Python "
"datetime and date objects as input.")
return process
def result_processor(self, dialect, coltype):
if self._reg:
return processors.str_to_datetime_processor_factory(
self._reg, datetime.datetime)
else:
return processors.str_to_datetime
class DATE(_DateTimeMixin, sqltypes.Date):
"""Represent a Python date object in SQLite using a string.
The default string storage format is::
"%(year)04d-%(month)02d-%(day)02d"
e.g.::
2011-03-15
The storage format can be customized to some degree using the
``storage_format`` and ``regexp`` parameters, such as::
import re
from sqlalchemy.dialects.sqlite import DATE
d = DATE(
storage_format="%(month)02d/%(day)02d/%(year)04d",
regexp=re.compile("(?P<month>\d+)/(?P<day>\d+)/(?P<year>\d+)")
)
:param storage_format: format string which will be applied to the
dict with keys year, month, and day.
:param regexp: regular expression which will be applied to
incoming result rows. If the regexp contains named groups, the
resulting match dict is applied to the Python date() constructor
as keyword arguments. Otherwise, if positional groups are used, the
the date() constructor is called with positional arguments via
``*map(int, match_obj.groups(0))``.
"""
_storage_format = "%(year)04d-%(month)02d-%(day)02d"
def bind_processor(self, dialect):
datetime_date = datetime.date
format = self._storage_format
def process(value):
if value is None:
return None
elif isinstance(value, datetime_date):
return format % {
'year': value.year,
'month': value.month,
'day': value.day,
}
else:
raise TypeError("SQLite Date type only accepts Python "
"date objects as input.")
return process
def result_processor(self, dialect, coltype):
if self._reg:
return processors.str_to_datetime_processor_factory(
self._reg, datetime.date)
else:
return processors.str_to_date
class TIME(_DateTimeMixin, sqltypes.Time):
"""Represent a Python time object in SQLite using a string.
The default string storage format is::
"%(hour)02d:%(minute)02d:%(second)02d.%(microsecond)06d"
e.g.::
12:05:57.10558
The storage format can be customized to some degree using the
``storage_format`` and ``regexp`` parameters, such as::
import re
from sqlalchemy.dialects.sqlite import TIME
t = TIME(
storage_format="%(hour)02d-%(minute)02d-%(second)02d-%(microsecond)06d",
regexp=re.compile("(\d+)-(\d+)-(\d+)-(?:-(\d+))?")
)
:param storage_format: format string which will be applied to the
dict with keys hour, minute, second, and microsecond.
:param regexp: regular expression which will be applied to
incoming result rows. If the regexp contains named groups, the
resulting match dict is applied to the Python time() constructor
as keyword arguments. Otherwise, if positional groups are used, the
the time() constructor is called with positional arguments via
``*map(int, match_obj.groups(0))``.
"""
_storage_format = "%(hour)02d:%(minute)02d:%(second)02d.%(microsecond)06d"
def __init__(self, *args, **kwargs):
truncate_microseconds = kwargs.pop('truncate_microseconds', False)
super(TIME, self).__init__(*args, **kwargs)
if truncate_microseconds:
assert 'storage_format' not in kwargs, "You can specify only "\
"one of truncate_microseconds or storage_format."
assert 'regexp' not in kwargs, "You can specify only one of "\
"truncate_microseconds or regexp."
self._storage_format = "%(hour)02d:%(minute)02d:%(second)02d"
def bind_processor(self, dialect):
datetime_time = datetime.time
format = self._storage_format
def process(value):
if value is None:
return None
elif isinstance(value, datetime_time):
return format % {
'hour': value.hour,
'minute': value.minute,
'second': value.second,
'microsecond': value.microsecond,
}
else:
raise TypeError("SQLite Time type only accepts Python "
"time objects as input.")
return process
def result_processor(self, dialect, coltype):
if self._reg:
return processors.str_to_datetime_processor_factory(
self._reg, datetime.time)
else:
return processors.str_to_time
colspecs = {
sqltypes.Date: DATE,
sqltypes.DateTime: DATETIME,
sqltypes.Time: TIME,
}
ischema_names = {
'BIGINT': sqltypes.BIGINT,
'BLOB': sqltypes.BLOB,
'BOOL': sqltypes.BOOLEAN,
'BOOLEAN': sqltypes.BOOLEAN,
'CHAR': sqltypes.CHAR,
'DATE': sqltypes.DATE,
'DATETIME': sqltypes.DATETIME,
'DECIMAL': sqltypes.DECIMAL,
'FLOAT': sqltypes.FLOAT,
'INT': sqltypes.INTEGER,
'INTEGER': sqltypes.INTEGER,
'NUMERIC': sqltypes.NUMERIC,
'REAL': sqltypes.REAL,
'SMALLINT': sqltypes.SMALLINT,
'TEXT': sqltypes.TEXT,
'TIME': sqltypes.TIME,
'TIMESTAMP': sqltypes.TIMESTAMP,
'VARCHAR': sqltypes.VARCHAR,
'NVARCHAR': sqltypes.NVARCHAR,
'NCHAR': sqltypes.NCHAR,
}
class SQLiteCompiler(compiler.SQLCompiler):
extract_map = util.update_copy(
compiler.SQLCompiler.extract_map,
{
'month': '%m',
'day': '%d',
'year': '%Y',
'second': '%S',
'hour': '%H',
'doy': '%j',
'minute': '%M',
'epoch': '%s',
'dow': '%w',
'week': '%W'
})
def visit_now_func(self, fn, **kw):
return "CURRENT_TIMESTAMP"
def visit_localtimestamp_func(self, func, **kw):
return 'DATETIME(CURRENT_TIMESTAMP, "localtime")'
def visit_true(self, expr, **kw):
return '1'
def visit_false(self, expr, **kw):
return '0'
def visit_char_length_func(self, fn, **kw):
return "length%s" % self.function_argspec(fn)
def visit_cast(self, cast, **kwargs):
if self.dialect.supports_cast:
return super(SQLiteCompiler, self).visit_cast(cast)
else:
return self.process(cast.clause)
def visit_extract(self, extract, **kw):
try:
return "CAST(STRFTIME('%s', %s) AS INTEGER)" % (
self.extract_map[extract.field],
self.process(extract.expr, **kw)
)
except KeyError:
raise exc.CompileError(
"%s is not a valid extract argument." % extract.field)
def limit_clause(self, select):
text = ""
if select._limit is not None:
text += "\n LIMIT " + self.process(sql.literal(select._limit))
if select._offset is not None:
if select._limit is None:
text += "\n LIMIT " + self.process(sql.literal(-1))
text += " OFFSET " + self.process(sql.literal(select._offset))
else:
text += " OFFSET " + self.process(sql.literal(0))
return text
def for_update_clause(self, select):
# sqlite has no "FOR UPDATE" AFAICT
return ''
class SQLiteDDLCompiler(compiler.DDLCompiler):
def get_column_specification(self, column, **kwargs):
coltype = self.dialect.type_compiler.process(column.type)
colspec = self.preparer.format_column(column) + " " + coltype
default = self.get_column_default_string(column)
if default is not None:
colspec += " DEFAULT " + default
if not column.nullable:
colspec += " NOT NULL"
if (column.primary_key and
column.table.kwargs.get('sqlite_autoincrement', False) and
len(column.table.primary_key.columns) == 1 and
issubclass(column.type._type_affinity, sqltypes.Integer) and
not column.foreign_keys):
colspec += " PRIMARY KEY AUTOINCREMENT"
return colspec
def visit_primary_key_constraint(self, constraint):
# for columns with sqlite_autoincrement=True,
# the PRIMARY KEY constraint can only be inline
# with the column itself.
if len(constraint.columns) == 1:
c = list(constraint)[0]
if c.primary_key and \
c.table.kwargs.get('sqlite_autoincrement', False) and \
issubclass(c.type._type_affinity, sqltypes.Integer) and \
not c.foreign_keys:
return None
return super(SQLiteDDLCompiler, self).\
visit_primary_key_constraint(constraint)
def visit_foreign_key_constraint(self, constraint):
local_table = constraint._elements.values()[0].parent.table
remote_table = list(constraint._elements.values())[0].column.table
if local_table.schema != remote_table.schema:
return None
else:
return super(SQLiteDDLCompiler, self).visit_foreign_key_constraint(constraint)
def define_constraint_remote_table(self, constraint, table, preparer):
"""Format the remote table clause of a CREATE CONSTRAINT clause."""
return preparer.format_table(table, use_schema=False)
def visit_create_index(self, create):
return super(SQLiteDDLCompiler, self).\
visit_create_index(create, include_table_schema=False)
class SQLiteTypeCompiler(compiler.GenericTypeCompiler):
def visit_large_binary(self, type_):
return self.visit_BLOB(type_)
class SQLiteIdentifierPreparer(compiler.IdentifierPreparer):
reserved_words = set([
'add', 'after', 'all', 'alter', 'analyze', 'and', 'as', 'asc',
'attach', 'autoincrement', 'before', 'begin', 'between', 'by',
'cascade', 'case', 'cast', 'check', 'collate', 'column', 'commit',
'conflict', 'constraint', 'create', 'cross', 'current_date',
'current_time', 'current_timestamp', 'database', 'default',
'deferrable', 'deferred', 'delete', 'desc', 'detach', 'distinct',
'drop', 'each', 'else', 'end', 'escape', 'except', 'exclusive',
'explain', 'false', 'fail', 'for', 'foreign', 'from', 'full', 'glob',
'group', 'having', 'if', 'ignore', 'immediate', 'in', 'index',
'indexed', 'initially', 'inner', 'insert', 'instead', 'intersect',
'into', 'is', 'isnull', 'join', 'key', 'left', 'like', 'limit',
'match', 'natural', 'not', 'notnull', 'null', 'of', 'offset', 'on',
'or', 'order', 'outer', 'plan', 'pragma', 'primary', 'query',
'raise', 'references', 'reindex', 'rename', 'replace', 'restrict',
'right', 'rollback', 'row', 'select', 'set', 'table', 'temp',
'temporary', 'then', 'to', 'transaction', 'trigger', 'true', 'union',
'unique', 'update', 'using', 'vacuum', 'values', 'view', 'virtual',
'when', 'where',
])
def format_index(self, index, use_schema=True, name=None):
"""Prepare a quoted index and schema name."""
if name is None:
name = index.name
result = self.quote(name, index.quote)
if (not self.omit_schema and
use_schema and
getattr(index.table, "schema", None)):
result = self.quote_schema(
index.table.schema, index.table.quote_schema) + "." + result
return result
class SQLiteExecutionContext(default.DefaultExecutionContext):
@util.memoized_property
def _preserve_raw_colnames(self):
return self.execution_options.get("sqlite_raw_colnames", False)
def _translate_colname(self, colname):
# adjust for dotted column names. SQLite
# in the case of UNION may store col names as
# "tablename.colname"
# in cursor.description
if not self._preserve_raw_colnames and "." in colname:
return colname.split(".")[1], colname
else:
return colname, None
class SQLiteDialect(default.DefaultDialect):
name = 'sqlite'
supports_alter = False
supports_unicode_statements = True
supports_unicode_binds = True
supports_default_values = True
supports_empty_insert = False
supports_cast = True
supports_multivalues_insert = True
default_paramstyle = 'qmark'
execution_ctx_cls = SQLiteExecutionContext
statement_compiler = SQLiteCompiler
ddl_compiler = SQLiteDDLCompiler
type_compiler = SQLiteTypeCompiler
preparer = SQLiteIdentifierPreparer
ischema_names = ischema_names
colspecs = colspecs
isolation_level = None
supports_cast = True
supports_default_values = True
_broken_fk_pragma_quotes = False
def __init__(self, isolation_level=None, native_datetime=False, **kwargs):
default.DefaultDialect.__init__(self, **kwargs)
self.isolation_level = isolation_level
# this flag used by pysqlite dialect, and perhaps others in the
# future, to indicate the driver is handling date/timestamp
# conversions (and perhaps datetime/time as well on some
# hypothetical driver ?)
self.native_datetime = native_datetime
if self.dbapi is not None:
self.supports_default_values = \
self.dbapi.sqlite_version_info >= (3, 3, 8)
self.supports_cast = \
self.dbapi.sqlite_version_info >= (3, 2, 3)
self.supports_multivalues_insert = \
self.dbapi.sqlite_version_info >= (3, 7, 11)
# http://www.sqlite.org/releaselog/3_7_11.html
# see http://www.sqlalchemy.org/trac/ticket/2568
# as well as http://www.sqlite.org/src/info/600482d161
self._broken_fk_pragma_quotes = \
self.dbapi.sqlite_version_info < (3, 6, 14)
_isolation_lookup = {
'READ UNCOMMITTED': 1,
'SERIALIZABLE': 0
}
def set_isolation_level(self, connection, level):
try:
isolation_level = self._isolation_lookup[level.replace('_', ' ')]
except KeyError:
raise exc.ArgumentError(
"Invalid value '%s' for isolation_level. "
"Valid isolation levels for %s are %s" %
(level, self.name, ", ".join(self._isolation_lookup))
)
cursor = connection.cursor()
cursor.execute("PRAGMA read_uncommitted = %d" % isolation_level)
cursor.close()
def get_isolation_level(self, connection):
cursor = connection.cursor()
cursor.execute('PRAGMA read_uncommitted')
res = cursor.fetchone()
if res:
value = res[0]
else:
# http://www.sqlite.org/changes.html#version_3_3_3
# "Optional READ UNCOMMITTED isolation (instead of the
# default isolation level of SERIALIZABLE) and
# table level locking when database connections
# share a common cache.""
# pre-SQLite 3.3.0 default to 0
value = 0
cursor.close()
if value == 0:
return "SERIALIZABLE"
elif value == 1:
return "READ UNCOMMITTED"
else:
assert False, "Unknown isolation level %s" % value
def on_connect(self):
if self.isolation_level is not None:
def connect(conn):
self.set_isolation_level(conn, self.isolation_level)
return connect
else:
return None
@reflection.cache
def get_table_names(self, connection, schema=None, **kw):
if schema is not None:
qschema = self.identifier_preparer.quote_identifier(schema)
master = '%s.sqlite_master' % qschema
s = ("SELECT name FROM %s "
"WHERE type='table' ORDER BY name") % (master,)
rs = connection.execute(s)
else:
try:
s = ("SELECT name FROM "
" (SELECT * FROM sqlite_master UNION ALL "
" SELECT * FROM sqlite_temp_master) "
"WHERE type='table' ORDER BY name")
rs = connection.execute(s)
except exc.DBAPIError:
s = ("SELECT name FROM sqlite_master "
"WHERE type='table' ORDER BY name")
rs = connection.execute(s)
return [row[0] for row in rs]
def has_table(self, connection, table_name, schema=None):
quote = self.identifier_preparer.quote_identifier
if schema is not None:
pragma = "PRAGMA %s." % quote(schema)
else:
pragma = "PRAGMA "
qtable = quote(table_name)
statement = "%stable_info(%s)" % (pragma, qtable)
cursor = _pragma_cursor(connection.execute(statement))
row = cursor.fetchone()
# consume remaining rows, to work around
# http://www.sqlite.org/cvstrac/tktview?tn=1884
while not cursor.closed and cursor.fetchone() is not None:
pass
return (row is not None)
@reflection.cache
def get_view_names(self, connection, schema=None, **kw):
if schema is not None:
qschema = self.identifier_preparer.quote_identifier(schema)
master = '%s.sqlite_master' % qschema
s = ("SELECT name FROM %s "
"WHERE type='view' ORDER BY name") % (master,)
rs = connection.execute(s)
else:
try:
s = ("SELECT name FROM "
" (SELECT * FROM sqlite_master UNION ALL "
" SELECT * FROM sqlite_temp_master) "
"WHERE type='view' ORDER BY name")
rs = connection.execute(s)
except exc.DBAPIError:
s = ("SELECT name FROM sqlite_master "
"WHERE type='view' ORDER BY name")
rs = connection.execute(s)
return [row[0] for row in rs]
@reflection.cache
def get_view_definition(self, connection, view_name, schema=None, **kw):
quote = self.identifier_preparer.quote_identifier
if schema is not None:
qschema = self.identifier_preparer.quote_identifier(schema)
master = '%s.sqlite_master' % qschema
s = ("SELECT sql FROM %s WHERE name = '%s'"
"AND type='view'") % (master, view_name)
rs = connection.execute(s)
else:
try:
s = ("SELECT sql FROM "
" (SELECT * FROM sqlite_master UNION ALL "
" SELECT * FROM sqlite_temp_master) "
"WHERE name = '%s' "
"AND type='view'") % view_name
rs = connection.execute(s)
except exc.DBAPIError:
s = ("SELECT sql FROM sqlite_master WHERE name = '%s' "
"AND type='view'") % view_name
rs = connection.execute(s)
result = rs.fetchall()
if result:
return result[0].sql
@reflection.cache
def get_columns(self, connection, table_name, schema=None, **kw):
quote = self.identifier_preparer.quote_identifier
if schema is not None:
pragma = "PRAGMA %s." % quote(schema)
else:
pragma = "PRAGMA "
qtable = quote(table_name)
statement = "%stable_info(%s)" % (pragma, qtable)
c = _pragma_cursor(connection.execute(statement))
rows = c.fetchall()
columns = []
for row in rows:
(name, type_, nullable, default, primary_key) = \
(row[1], row[2].upper(), not row[3],
row[4], row[5])
columns.append(self._get_column_info(name, type_, nullable,
default, primary_key))
return columns
def _get_column_info(self, name, type_, nullable,
default, primary_key):
match = re.match(r'(\w+)(\(.*?\))?', type_)
if match:
coltype = match.group(1)
args = match.group(2)
else:
coltype = "VARCHAR"
args = ''
try:
coltype = self.ischema_names[coltype]
if args is not None:
args = re.findall(r'(\d+)', args)
coltype = coltype(*[int(a) for a in args])
except KeyError:
util.warn("Did not recognize type '%s' of column '%s'" %
(coltype, name))
coltype = sqltypes.NullType()
if default is not None:
default = unicode(default)
return {
'name': name,
'type': coltype,
'nullable': nullable,
'default': default,
'autoincrement': default is None,
'primary_key': primary_key
}
@reflection.cache
def get_pk_constraint(self, connection, table_name, schema=None, **kw):
cols = self.get_columns(connection, table_name, schema, **kw)
pkeys = []
for col in cols:
if col['primary_key']:
pkeys.append(col['name'])
return {'constrained_columns': pkeys, 'name': None}
@reflection.cache
def get_foreign_keys(self, connection, table_name, schema=None, **kw):
quote = self.identifier_preparer.quote_identifier
if schema is not None:
pragma = "PRAGMA %s." % quote(schema)
else:
pragma = "PRAGMA "
qtable = quote(table_name)
statement = "%sforeign_key_list(%s)" % (pragma, qtable)
c = _pragma_cursor(connection.execute(statement))
fkeys = []
fks = {}
while True:
row = c.fetchone()
if row is None:
break
(numerical_id, rtbl, lcol, rcol) = (row[0], row[2], row[3], row[4])
self._parse_fk(fks, fkeys, numerical_id, rtbl, lcol, rcol)
return fkeys
def _parse_fk(self, fks, fkeys, numerical_id, rtbl, lcol, rcol):
# sqlite won't return rcol if the table
# was created with REFERENCES <tablename>, no col
if rcol is None:
rcol = lcol
if self._broken_fk_pragma_quotes:
rtbl = re.sub(r'^[\"\[`\']|[\"\]`\']$', '', rtbl)
try:
fk = fks[numerical_id]
except KeyError:
fk = {
'name': None,
'constrained_columns': [],
'referred_schema': None,
'referred_table': rtbl,
'referred_columns': []
}
fkeys.append(fk)
fks[numerical_id] = fk
if lcol not in fk['constrained_columns']:
fk['constrained_columns'].append(lcol)
if rcol not in fk['referred_columns']:
fk['referred_columns'].append(rcol)
return fk
@reflection.cache
def get_indexes(self, connection, table_name, schema=None, **kw):
quote = self.identifier_preparer.quote_identifier
if schema is not None:
pragma = "PRAGMA %s." % quote(schema)
else:
pragma = "PRAGMA "
include_auto_indexes = kw.pop('include_auto_indexes', False)
qtable = quote(table_name)
statement = "%sindex_list(%s)" % (pragma, qtable)
c = _pragma_cursor(connection.execute(statement))
indexes = []
while True:
row = c.fetchone()
if row is None:
break
# ignore implicit primary key index.
# http://www.mail-archive.com/sqlite-users@sqlite.org/msg30517.html
elif (not include_auto_indexes and
row[1].startswith('sqlite_autoindex')):
continue
indexes.append(dict(name=row[1], column_names=[], unique=row[2]))
# loop thru unique indexes to get the column names.
for idx in indexes:
statement = "%sindex_info(%s)" % (pragma, quote(idx['name']))
c = connection.execute(statement)
cols = idx['column_names']
while True:
row = c.fetchone()
if row is None:
break
cols.append(row[2])
return indexes
def _pragma_cursor(cursor):
"""work around SQLite issue whereby cursor.description
is blank when PRAGMA returns no rows."""
if cursor.closed:
cursor.fetchone = lambda: None
cursor.fetchall = lambda: []
return cursor

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lib/sqlalchemy/dialects/sqlite/pysqlite.py Normal file
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@@ -0,0 +1,335 @@
# sqlite/pysqlite.py
# Copyright (C) 2005-2013 the SQLAlchemy authors and contributors <see AUTHORS file>
#
# This module is part of SQLAlchemy and is released under
# the MIT License: http://www.opensource.org/licenses/mit-license.php
"""
.. dialect:: sqlite+pysqlite
:name: pysqlite
:dbapi: sqlite3
:connectstring: sqlite+pysqlite:///file_path
:url: http://docs.python.org/library/sqlite3.html
Note that ``pysqlite`` is the same driver as the ``sqlite3``
module included with the Python distribution.
Driver
------
When using Python 2.5 and above, the built in ``sqlite3`` driver is
already installed and no additional installation is needed. Otherwise,
the ``pysqlite2`` driver needs to be present. This is the same driver as
``sqlite3``, just with a different name.
The ``pysqlite2`` driver will be loaded first, and if not found, ``sqlite3``
is loaded. This allows an explicitly installed pysqlite driver to take
precedence over the built in one. As with all dialects, a specific
DBAPI module may be provided to :func:`~sqlalchemy.create_engine()` to control
this explicitly::
from sqlite3 import dbapi2 as sqlite
e = create_engine('sqlite+pysqlite:///file.db', module=sqlite)
Connect Strings
---------------
The file specification for the SQLite database is taken as the "database"
portion of the URL. Note that the format of a SQLAlchemy url is::
driver://user:pass@host/database
This means that the actual filename to be used starts with the characters to
the **right** of the third slash. So connecting to a relative filepath
looks like::
# relative path
e = create_engine('sqlite:///path/to/database.db')
An absolute path, which is denoted by starting with a slash, means you
need **four** slashes::
# absolute path
e = create_engine('sqlite:////path/to/database.db')
To use a Windows path, regular drive specifications and backslashes can be
used. Double backslashes are probably needed::
# absolute path on Windows
e = create_engine('sqlite:///C:\\\\path\\\\to\\\\database.db')
The sqlite ``:memory:`` identifier is the default if no filepath is
present. Specify ``sqlite://`` and nothing else::
# in-memory database
e = create_engine('sqlite://')
Compatibility with sqlite3 "native" date and datetime types
-----------------------------------------------------------
The pysqlite driver includes the sqlite3.PARSE_DECLTYPES and
sqlite3.PARSE_COLNAMES options, which have the effect of any column
or expression explicitly cast as "date" or "timestamp" will be converted
to a Python date or datetime object. The date and datetime types provided
with the pysqlite dialect are not currently compatible with these options,
since they render the ISO date/datetime including microseconds, which
pysqlite's driver does not. Additionally, SQLAlchemy does not at
this time automatically render the "cast" syntax required for the
freestanding functions "current_timestamp" and "current_date" to return
datetime/date types natively. Unfortunately, pysqlite
does not provide the standard DBAPI types in ``cursor.description``,
leaving SQLAlchemy with no way to detect these types on the fly
without expensive per-row type checks.
Keeping in mind that pysqlite's parsing option is not recommended,
nor should be necessary, for use with SQLAlchemy, usage of PARSE_DECLTYPES
can be forced if one configures "native_datetime=True" on create_engine()::
engine = create_engine('sqlite://',
connect_args={'detect_types': sqlite3.PARSE_DECLTYPES|sqlite3.PARSE_COLNAMES},
native_datetime=True
)
With this flag enabled, the DATE and TIMESTAMP types (but note - not the
DATETIME or TIME types...confused yet ?) will not perform any bind parameter
or result processing. Execution of "func.current_date()" will return a string.
"func.current_timestamp()" is registered as returning a DATETIME type in
SQLAlchemy, so this function still receives SQLAlchemy-level result processing.
.. _pysqlite_threading_pooling:
Threading/Pooling Behavior
---------------------------
Pysqlite's default behavior is to prohibit the usage of a single connection
in more than one thread. This is originally intended to work with older
versions of SQLite that did not support multithreaded operation under
various circumstances. In particular, older SQLite versions
did not allow a ``:memory:`` database to be used in multiple threads
under any circumstances.
Pysqlite does include a now-undocumented flag known as
``check_same_thread`` which will disable this check, however note that pysqlite
connections are still not safe to use in concurrently in multiple threads.
In particular, any statement execution calls would need to be externally
mutexed, as Pysqlite does not provide for thread-safe propagation of error
messages among other things. So while even ``:memory:`` databases can be
shared among threads in modern SQLite, Pysqlite doesn't provide enough
thread-safety to make this usage worth it.
SQLAlchemy sets up pooling to work with Pysqlite's default behavior:
* When a ``:memory:`` SQLite database is specified, the dialect by default
will use :class:`.SingletonThreadPool`. This pool maintains a single
connection per thread, so that all access to the engine within the current
thread use the same ``:memory:`` database - other threads would access a
different ``:memory:`` database.
* When a file-based database is specified, the dialect will use
:class:`.NullPool` as the source of connections. This pool closes and
discards connections which are returned to the pool immediately. SQLite
file-based connections have extremely low overhead, so pooling is not
necessary. The scheme also prevents a connection from being used again in
a different thread and works best with SQLite's coarse-grained file locking.
.. versionchanged:: 0.7
Default selection of :class:`.NullPool` for SQLite file-based databases.
Previous versions select :class:`.SingletonThreadPool` by
default for all SQLite databases.
Using a Memory Database in Multiple Threads
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
To use a ``:memory:`` database in a multithreaded scenario, the same connection
object must be shared among threads, since the database exists
only within the scope of that connection. The
:class:`.StaticPool` implementation will maintain a single connection
globally, and the ``check_same_thread`` flag can be passed to Pysqlite
as ``False``::
from sqlalchemy.pool import StaticPool
engine = create_engine('sqlite://',
connect_args={'check_same_thread':False},
poolclass=StaticPool)
Note that using a ``:memory:`` database in multiple threads requires a recent
version of SQLite.
Using Temporary Tables with SQLite
^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
Due to the way SQLite deals with temporary tables, if you wish to use a
temporary table in a file-based SQLite database across multiple checkouts
from the connection pool, such as when using an ORM :class:`.Session` where
the temporary table should continue to remain after :meth:`.commit` or
:meth:`.rollback` is called, a pool which maintains a single connection must
be used. Use :class:`.SingletonThreadPool` if the scope is only needed
within the current thread, or :class:`.StaticPool` is scope is needed within
multiple threads for this case::
# maintain the same connection per thread
from sqlalchemy.pool import SingletonThreadPool
engine = create_engine('sqlite:///mydb.db',
poolclass=SingletonThreadPool)
# maintain the same connection across all threads
from sqlalchemy.pool import StaticPool
engine = create_engine('sqlite:///mydb.db',
poolclass=StaticPool)
Note that :class:`.SingletonThreadPool` should be configured for the number
of threads that are to be used; beyond that number, connections will be
closed out in a non deterministic way.
Unicode
-------
The pysqlite driver only returns Python ``unicode`` objects in result sets,
never plain strings, and accommodates ``unicode`` objects within bound
parameter values in all cases. Regardless of the SQLAlchemy string type in
use, string-based result values will by Python ``unicode`` in Python 2.
The :class:`.Unicode` type should still be used to indicate those columns that
require unicode, however, so that non-``unicode`` values passed inadvertently
will emit a warning. Pysqlite will emit an error if a non-``unicode`` string
is passed containing non-ASCII characters.
.. _pysqlite_serializable:
Serializable Transaction Isolation
----------------------------------
The pysqlite DBAPI driver has a long-standing bug in which transactional
state is not begun until the first DML statement, that is INSERT, UPDATE
or DELETE, is emitted. A SELECT statement will not cause transactional
state to begin. While this mode of usage is fine for typical situations
and has the advantage that the SQLite database file is not prematurely
locked, it breaks serializable transaction isolation, which requires
that the database file be locked upon any SQL being emitted.
To work around this issue, the ``BEGIN`` keyword can be emitted
at the start of each transaction. The following recipe establishes
a :meth:`.ConnectionEvents.begin` handler to achieve this::
from sqlalchemy import create_engine, event
engine = create_engine("sqlite:///myfile.db", isolation_level='SERIALIZABLE')
@event.listens_for(engine, "begin")
def do_begin(conn):
conn.execute("BEGIN")
"""
from sqlalchemy.dialects.sqlite.base import SQLiteDialect, DATETIME, DATE
from sqlalchemy import exc, pool
from sqlalchemy import types as sqltypes
from sqlalchemy import util
import os
class _SQLite_pysqliteTimeStamp(DATETIME):
def bind_processor(self, dialect):
if dialect.native_datetime:
return None
else:
return DATETIME.bind_processor(self, dialect)
def result_processor(self, dialect, coltype):
if dialect.native_datetime:
return None
else:
return DATETIME.result_processor(self, dialect, coltype)
class _SQLite_pysqliteDate(DATE):
def bind_processor(self, dialect):
if dialect.native_datetime:
return None
else:
return DATE.bind_processor(self, dialect)
def result_processor(self, dialect, coltype):
if dialect.native_datetime:
return None
else:
return DATE.result_processor(self, dialect, coltype)
class SQLiteDialect_pysqlite(SQLiteDialect):
default_paramstyle = 'qmark'
colspecs = util.update_copy(
SQLiteDialect.colspecs,
{
sqltypes.Date: _SQLite_pysqliteDate,
sqltypes.TIMESTAMP: _SQLite_pysqliteTimeStamp,
}
)
# Py3K
#description_encoding = None
driver = 'pysqlite'
def __init__(self, **kwargs):
SQLiteDialect.__init__(self, **kwargs)
if self.dbapi is not None:
sqlite_ver = self.dbapi.version_info
if sqlite_ver < (2, 1, 3):
util.warn(
("The installed version of pysqlite2 (%s) is out-dated "
"and will cause errors in some cases. Version 2.1.3 "
"or greater is recommended.") %
'.'.join([str(subver) for subver in sqlite_ver]))
@classmethod
def dbapi(cls):
try:
from pysqlite2 import dbapi2 as sqlite
except ImportError, e:
try:
from sqlite3 import dbapi2 as sqlite # try 2.5+ stdlib name.
except ImportError:
raise e
return sqlite
@classmethod
def get_pool_class(cls, url):
if url.database and url.database != ':memory:':
return pool.NullPool
else:
return pool.SingletonThreadPool
def _get_server_version_info(self, connection):
return self.dbapi.sqlite_version_info
def create_connect_args(self, url):
if url.username or url.password or url.host or url.port:
raise exc.ArgumentError(
"Invalid SQLite URL: %s\n"
"Valid SQLite URL forms are:\n"
" sqlite:///:memory: (or, sqlite://)\n"
" sqlite:///relative/path/to/file.db\n"
" sqlite:////absolute/path/to/file.db" % (url,))
filename = url.database or ':memory:'
if filename != ':memory:':
filename = os.path.abspath(filename)
opts = url.query.copy()
util.coerce_kw_type(opts, 'timeout', float)
util.coerce_kw_type(opts, 'isolation_level', str)
util.coerce_kw_type(opts, 'detect_types', int)
util.coerce_kw_type(opts, 'check_same_thread', bool)
util.coerce_kw_type(opts, 'cached_statements', int)
return ([filename], opts)
def is_disconnect(self, e, connection, cursor):
return isinstance(e, self.dbapi.ProgrammingError) and \
"Cannot operate on a closed database." in str(e)
dialect = SQLiteDialect_pysqlite