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jianbo
2019-07-17 16:36:59 +08:00
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venv/Lib/site-packages/sqlalchemy/dialects/sqlite/__init__.py Normal file
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# sqlite/__init__.py
# Copyright (C) 2005-2019 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 . import base # noqa
from . import pysqlcipher # noqa
from . import pysqlite # noqa
from .base import BLOB
from .base import BOOLEAN
from .base import CHAR
from .base import DATE
from .base import DATETIME
from .base import DECIMAL
from .base import FLOAT
from .base import INTEGER
from .base import JSON
from .base import NUMERIC
from .base import REAL
from .base import SMALLINT
from .base import TEXT
from .base import TIME
from .base import TIMESTAMP
from .base import VARCHAR
# default dialect
base.dialect = dialect = pysqlite.dialect
__all__ = (
"BLOB",
"BOOLEAN",
"CHAR",
"DATE",
"DATETIME",
"DECIMAL",
"FLOAT",
"INTEGER",
"JSON",
"NUMERIC",
"SMALLINT",
"TEXT",
"TIME",
"TIMESTAMP",
"VARCHAR",
"REAL",
"dialect",
)

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venv/Lib/site-packages/sqlalchemy/dialects/sqlite/base.py Normal file
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venv/Lib/site-packages/sqlalchemy/dialects/sqlite/json.py Normal file
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from ... import types as sqltypes
class JSON(sqltypes.JSON):
"""SQLite JSON type.
SQLite supports JSON as of version 3.9 through its JSON1_ extension. Note
that JSON1_ is a
`loadable extension <https://www.sqlite.org/loadext.html>`_ and as such
may not be available, or may require run-time loading.
The :class:`.sqlite.JSON` type supports persistence of JSON values
as well as the core index operations provided by :class:`.types.JSON`
datatype, by adapting the operations to render the ``JSON_EXTRACT``
function wrapped in the ``JSON_QUOTE`` function at the database level.
Extracted values are quoted in order to ensure that the results are
always JSON string values.
.. versionadded:: 1.3
.. seealso::
JSON1_
.. _JSON1: https://www.sqlite.org/json1.html
"""
# Note: these objects currently match exactly those of MySQL, however since
# these are not generalizable to all JSON implementations, remain separately
# implemented for each dialect.
class _FormatTypeMixin(object):
def _format_value(self, value):
raise NotImplementedError()
def bind_processor(self, dialect):
super_proc = self.string_bind_processor(dialect)
def process(value):
value = self._format_value(value)
if super_proc:
value = super_proc(value)
return value
return process
def literal_processor(self, dialect):
super_proc = self.string_literal_processor(dialect)
def process(value):
value = self._format_value(value)
if super_proc:
value = super_proc(value)
return value
return process
class JSONIndexType(_FormatTypeMixin, sqltypes.JSON.JSONIndexType):
def _format_value(self, value):
if isinstance(value, int):
value = "$[%s]" % value
else:
value = '$."%s"' % value
return value
class JSONPathType(_FormatTypeMixin, sqltypes.JSON.JSONPathType):
def _format_value(self, value):
return "$%s" % (
"".join(
[
"[%s]" % elem if isinstance(elem, int) else '."%s"' % elem
for elem in value
]
)
)

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venv/Lib/site-packages/sqlalchemy/dialects/sqlite/pysqlcipher.py Normal file
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# sqlite/pysqlcipher.py
# Copyright (C) 2005-2019 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+pysqlcipher
:name: pysqlcipher
:dbapi: pysqlcipher
:connectstring: sqlite+pysqlcipher://:passphrase/file_path[?kdf_iter=<iter>]
:url: https://pypi.python.org/pypi/pysqlcipher
``pysqlcipher`` is a fork of the standard ``pysqlite`` driver to make
use of the `SQLCipher <https://www.zetetic.net/sqlcipher>`_ backend.
``pysqlcipher3`` is a fork of ``pysqlcipher`` for Python 3. This dialect
will attempt to import it if ``pysqlcipher`` is non-present.
.. versionadded:: 1.1.4 - added fallback import for pysqlcipher3
.. versionadded:: 0.9.9 - added pysqlcipher dialect
Driver
------
The driver here is the
`pysqlcipher <https://pypi.python.org/pypi/pysqlcipher>`_
driver, which makes use of the SQLCipher engine. This system essentially
introduces new PRAGMA commands to SQLite which allows the setting of a
passphrase and other encryption parameters, allowing the database
file to be encrypted.
`pysqlcipher3` is a fork of `pysqlcipher` with support for Python 3,
the driver is the same.
Connect Strings
---------------
The format of the connect string is in every way the same as that
of the :mod:`~sqlalchemy.dialects.sqlite.pysqlite` driver, except that the
"password" field is now accepted, which should contain a passphrase::
e = create_engine('sqlite+pysqlcipher://:testing@/foo.db')
For an absolute file path, two leading slashes should be used for the
database name::
e = create_engine('sqlite+pysqlcipher://:testing@//path/to/foo.db')
A selection of additional encryption-related pragmas supported by SQLCipher
as documented at https://www.zetetic.net/sqlcipher/sqlcipher-api/ can be passed
in the query string, and will result in that PRAGMA being called for each
new connection. Currently, ``cipher``, ``kdf_iter``
``cipher_page_size`` and ``cipher_use_hmac`` are supported::
e = create_engine('sqlite+pysqlcipher://:testing@/foo.db?cipher=aes-256-cfb&kdf_iter=64000')
Pooling Behavior
----------------
The driver makes a change to the default pool behavior of pysqlite
as described in :ref:`pysqlite_threading_pooling`. The pysqlcipher driver
has been observed to be significantly slower on connection than the
pysqlite driver, most likely due to the encryption overhead, so the
dialect here defaults to using the :class:`.SingletonThreadPool`
implementation,
instead of the :class:`.NullPool` pool used by pysqlite. As always, the pool
implementation is entirely configurable using the
:paramref:`.create_engine.poolclass` parameter; the :class:`.StaticPool` may
be more feasible for single-threaded use, or :class:`.NullPool` may be used
to prevent unencrypted connections from being held open for long periods of
time, at the expense of slower startup time for new connections.
""" # noqa
from __future__ import absolute_import
from .pysqlite import SQLiteDialect_pysqlite
from ... import pool
from ...engine import url as _url
class SQLiteDialect_pysqlcipher(SQLiteDialect_pysqlite):
driver = "pysqlcipher"
pragmas = ("kdf_iter", "cipher", "cipher_page_size", "cipher_use_hmac")
@classmethod
def dbapi(cls):
try:
from pysqlcipher import dbapi2 as sqlcipher
except ImportError as e:
try:
from pysqlcipher3 import dbapi2 as sqlcipher
except ImportError:
raise e
return sqlcipher
@classmethod
def get_pool_class(cls, url):
return pool.SingletonThreadPool
def connect(self, *cargs, **cparams):
passphrase = cparams.pop("passphrase", "")
pragmas = dict((key, cparams.pop(key, None)) for key in self.pragmas)
conn = super(SQLiteDialect_pysqlcipher, self).connect(
*cargs, **cparams
)
conn.execute('pragma key="%s"' % passphrase)
for prag, value in pragmas.items():
if value is not None:
conn.execute('pragma %s="%s"' % (prag, value))
return conn
def create_connect_args(self, url):
super_url = _url.URL(
url.drivername,
username=url.username,
host=url.host,
database=url.database,
query=url.query,
)
c_args, opts = super(
SQLiteDialect_pysqlcipher, self
).create_connect_args(super_url)
opts["passphrase"] = url.password
return c_args, opts
dialect = SQLiteDialect_pysqlcipher

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# sqlite/pysqlite.py
# Copyright (C) 2005-2019 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
r"""
.. 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.
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:`.Session.commit` or
:meth:`.Session.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 isolation / Savepoints / Transactional DDL
-------------------------------------------------------
In the section :ref:`sqlite_concurrency`, we refer to the pysqlite
driver's assortment of issues that prevent several features of SQLite
from working correctly. The pysqlite DBAPI driver has several
long-standing bugs which impact the correctness of its transactional
behavior. In its default mode of operation, SQLite features such as
SERIALIZABLE isolation, transactional DDL, and SAVEPOINT support are
non-functional, and in order to use these features, workarounds must
be taken.
The issue is essentially that the driver attempts to second-guess the user's
intent, failing to start transactions and sometimes ending them prematurely, in
an effort to minimize the SQLite databases's file locking behavior, even
though SQLite itself uses "shared" locks for read-only activities.
SQLAlchemy chooses to not alter this behavior by default, as it is the
long-expected behavior of the pysqlite driver; if and when the pysqlite
driver attempts to repair these issues, that will be more of a driver towards
defaults for SQLAlchemy.
The good news is that with a few events, we can implement transactional
support fully, by disabling pysqlite's feature entirely and emitting BEGIN
ourselves. This is achieved using two event listeners::
from sqlalchemy import create_engine, event
engine = create_engine("sqlite:///myfile.db")
@event.listens_for(engine, "connect")
def do_connect(dbapi_connection, connection_record):
# disable pysqlite's emitting of the BEGIN statement entirely.
# also stops it from emitting COMMIT before any DDL.
dbapi_connection.isolation_level = None
@event.listens_for(engine, "begin")
def do_begin(conn):
# emit our own BEGIN
conn.execute("BEGIN")
Above, we intercept a new pysqlite connection and disable any transactional
integration. Then, at the point at which SQLAlchemy knows that transaction
scope is to begin, we emit ``"BEGIN"`` ourselves.
When we take control of ``"BEGIN"``, we can also control directly SQLite's
locking modes, introduced at
`BEGIN TRANSACTION <http://sqlite.org/lang_transaction.html>`_,
by adding the desired locking mode to our ``"BEGIN"``::
@event.listens_for(engine, "begin")
def do_begin(conn):
conn.execute("BEGIN EXCLUSIVE")
.. seealso::
`BEGIN TRANSACTION <http://sqlite.org/lang_transaction.html>`_ -
on the SQLite site
`sqlite3 SELECT does not BEGIN a transaction <http://bugs.python.org/issue9924>`_ -
on the Python bug tracker
`sqlite3 module breaks transactions and potentially corrupts data <http://bugs.python.org/issue10740>`_ -
on the Python bug tracker
""" # noqa
import os
from .base import DATE
from .base import DATETIME
from .base import SQLiteDialect
from ... import exc
from ... import pool
from ... import types as sqltypes
from ... import util
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,
},
)
if not util.py2k:
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:
try:
from sqlite3 import dbapi2 as sqlite # try 2.5+ stdlib name.
except ImportError as e:
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