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106 lines (89 loc) · 3.68 KB
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import sqlalchemy
import os
import re
class ConnectionError(Exception):
pass
def rough_dict_get(dct, sought, default=None):
'''
Like dct.get(sought), but any key containing sought will do.
If there is a `@` in sought, seek each piece separately.
This lets `me@server` match `me:***@myserver/db`
'''
sought = sought.split('@')
for (key, val) in dct.items():
if not any(s.lower() not in key.lower() for s in sought):
return val
return default
class Connection(object):
current = None
connections = {}
@classmethod
def tell_format(cls):
return """Connection info needed in SQLAlchemy format, example:
postgresql://username:password@hostname/dbname
or an existing connection: %s""" % str(cls.connections.keys())
def __init__(self, connect_str=None, connect_args={}, creator=None):
try:
if creator:
engine = sqlalchemy.create_engine(connect_str, connect_args=connect_args, creator=creator)
else:
engine = sqlalchemy.create_engine(connect_str, connect_args=connect_args)
except: # TODO: bare except; but what's an ArgumentError?
print(self.tell_format())
raise
self.dialect = engine.url.get_dialect()
self.metadata = sqlalchemy.MetaData(bind=engine)
self.name = self.assign_name(engine)
self.session = engine.connect()
self.connections[repr(self.metadata.bind.url)] = self
self.connect_args = connect_args
Connection.current = self
@classmethod
def set(cls, descriptor, displaycon, connect_args={}, creator=None):
"Sets the current database connection"
if descriptor:
if isinstance(descriptor, Connection):
cls.current = descriptor
else:
existing = rough_dict_get(cls.connections, descriptor)
# http://docs.sqlalchemy.org/en/rel_0_9/core/engines.html#custom-dbapi-connect-arguments
cls.current = existing or Connection(descriptor, connect_args, creator)
else:
if cls.connections:
if displaycon:
print(cls.connection_list())
else:
if os.getenv('DATABASE_URL'):
cls.current = Connection(os.getenv('DATABASE_URL'), connect_args, creator)
else:
raise ConnectionError('Environment variable $DATABASE_URL not set, and no connect string given.')
return cls.current
@classmethod
def assign_name(cls, engine):
name = '%s@%s' % (engine.url.username or '', engine.url.database)
return name
@classmethod
def connection_list(cls):
result = []
for key in sorted(cls.connections):
engine_url = cls.connections[key].metadata.bind.url # type: sqlalchemy.engine.url.URL
if cls.connections[key] == cls.current:
template = ' * {}'
else:
template = ' {}'
result.append(template.format(engine_url.__repr__()))
return '\n'.join(result)
def _close(cls, descriptor):
if isinstance(descriptor, Connection):
conn = descriptor
else:
conn = cls.connections.get(descriptor) or \
cls.connections.get(descriptor.lower())
if not conn:
raise Exception("Could not close connection because it was not found amongst these: %s" \
%str(cls.connections.keys()))
cls.connections.pop(conn.name)
cls.connections.pop(str(conn.metadata.bind.url))
conn.session.close()
def close(self):
self.__class__._close(self)