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|
# engine/url.py
# Copyright (C) 2005-2011 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
"""Provides the :class:`~sqlalchemy.engine.url.URL` class which encapsulates
information about a database connection specification.
The URL object is created automatically when :func:`~sqlalchemy.engine.create_engine` is called
with a string argument; alternatively, the URL is a public-facing construct which can
be used directly and is also accepted directly by ``create_engine()``.
"""
import re, cgi, sys, urllib
from sqlalchemy import exc
class URL(object):
"""
Represent the components of a URL used to connect to a database.
This object is suitable to be passed directly to a
``create_engine()`` call. The fields of the URL are parsed from a
string by the ``module-level make_url()`` function. the string
format of the URL is an RFC-1738-style string.
All initialization parameters are available as public attributes.
:param drivername: the name of the database backend.
This name will correspond to a module in sqlalchemy/databases
or a third party plug-in.
:param username: The user name.
:param password: database password.
:param host: The name of the host.
:param port: The port number.
:param database: The database name.
:param query: A dictionary of options to be passed to the
dialect and/or the DBAPI upon connect.
"""
def __init__(self, drivername, username=None, password=None,
host=None, port=None, database=None, query=None):
self.drivername = drivername
self.username = username
self.password = password
self.host = host
if port is not None:
self.port = int(port)
else:
self.port = None
self.database = database
self.query = query or {}
def __str__(self):
s = self.drivername + "://"
if self.username is not None:
s += self.username
if self.password is not None:
s += ':' + urllib.quote_plus(self.password)
s += "@"
if self.host is not None:
s += self.host
if self.port is not None:
s += ':' + str(self.port)
if self.database is not None:
s += '/' + self.database
if self.query:
keys = self.query.keys()
keys.sort()
s += '?' + "&".join("%s=%s" % (k, self.query[k]) for k in keys)
return s
def __hash__(self):
return hash(str(self))
def __eq__(self, other):
return \
isinstance(other, URL) and \
self.drivername == other.drivername and \
self.username == other.username and \
self.password == other.password and \
self.host == other.host and \
self.database == other.database and \
self.query == other.query
def get_dialect(self):
"""Return the SQLAlchemy database dialect class corresponding
to this URL's driver name.
"""
try:
if '+' in self.drivername:
dialect, driver = self.drivername.split('+')
else:
dialect, driver = self.drivername, 'base'
module = __import__('sqlalchemy.dialects.%s' % (dialect, )).dialects
module = getattr(module, dialect)
module = getattr(module, driver)
return module.dialect
except ImportError:
module = self._load_entry_point()
if module is not None:
return module
else:
raise exc.ArgumentError(
"Could not determine dialect for '%s'." % self.drivername)
def _load_entry_point(self):
"""attempt to load this url's dialect from entry points, or return None
if pkg_resources is not installed or there is no matching entry point.
Raise ImportError if the actual load fails.
"""
try:
import pkg_resources
except ImportError:
return None
for res in pkg_resources.iter_entry_points('sqlalchemy.dialects'):
if res.name == self.drivername:
return res.load()
else:
return None
def translate_connect_args(self, names=[], **kw):
"""Translate url attributes into a dictionary of connection arguments.
Returns attributes of this url (`host`, `database`, `username`,
`password`, `port`) as a plain dictionary. The attribute names are
used as the keys by default. Unset or false attributes are omitted
from the final dictionary.
:param \**kw: Optional, alternate key names for url attributes.
:param names: Deprecated. Same purpose as the keyword-based alternate names,
but correlates the name to the original positionally.
"""
translated = {}
attribute_names = ['host', 'database', 'username', 'password', 'port']
for sname in attribute_names:
if names:
name = names.pop(0)
elif sname in kw:
name = kw[sname]
else:
name = sname
if name is not None and getattr(self, sname, False):
translated[name] = getattr(self, sname)
return translated
def make_url(name_or_url):
"""Given a string or unicode instance, produce a new URL instance.
The given string is parsed according to the RFC 1738 spec. If an
existing URL object is passed, just returns the object.
"""
if isinstance(name_or_url, basestring):
return _parse_rfc1738_args(name_or_url)
else:
return name_or_url
def _parse_rfc1738_args(name):
pattern = re.compile(r'''
(?P<name>[\w\+]+)://
(?:
(?P<username>[^:/]*)
(?::(?P<password>[^/]*))?
@)?
(?:
(?P<host>[^/:]*)
(?::(?P<port>[^/]*))?
)?
(?:/(?P<database>.*))?
'''
, re.X)
m = pattern.match(name)
if m is not None:
components = m.groupdict()
if components['database'] is not None:
tokens = components['database'].split('?', 2)
components['database'] = tokens[0]
query = (len(tokens) > 1 and dict(cgi.parse_qsl(tokens[1]))) or None
# Py2K
if query is not None:
query = dict((k.encode('ascii'), query[k]) for k in query)
# end Py2K
else:
query = None
components['query'] = query
if components['password'] is not None:
components['password'] = urllib.unquote_plus(components['password'])
name = components.pop('name')
return URL(name, **components)
else:
raise exc.ArgumentError(
"Could not parse rfc1738 URL from string '%s'" % name)
def _parse_keyvalue_args(name):
m = re.match( r'(\w+)://(.*)', name)
if m is not None:
(name, args) = m.group(1, 2)
opts = dict( cgi.parse_qsl( args ) )
return URL(name, *opts)
else:
return None
|
