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# Copyright (C) 2010 Leonard Thomas
#
# This file is part of Dodai.
#
# Dodai is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# Dodai is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with Dodai. If not, see <http://www.gnu.org/licenses/>.
from dodai.exception import DatabaseEmptyOptionException
from dodai.exception import DatabasePortException
from dodai.exception import DatabaseHostnameException
from dodai.exception import DatabaseProtocolException
from dodai.exception import DatabaseConnectionException
from dodai.exception import UnknownDatabaseConnectionException
from dodai.tools import list_to_english
class ConfigDatabases(object):
"""An object that is used for creating database connection objects
"""
def __init__(self, default_handler, default_name):
self.connections = {}
self._handlers = {}
DatabaseConnection.DEFAULT_HANDLER = default_name
self.add_handler(default_name, default_handler)
def add(self, sections):
"""Adds a dictionary of sections to this object that could
be used for creating database connection objects. The dictionary
should be formatted as follows:
sections[name] = {option: value, option: value, ....}
The 'name' is the section name. It is an identifier that is used
to load the database:
The options and values can have the following:
protocol: The database engine (postgresql, mysql, sqlite,
oracle, mssql etc..)
hostname: The hostname or ip address of the database server
port: The port that should be used to connect to the
database server should be a number between 1
and 65535
username: The username used to connect to the database server
password: The password used to connect to the database server
database: The database to connect to once connected to the
server
schema: The schema that will be used. This option does
not do anything but will exist in the db object
for use
filename: The file path to the database file (sqlite)
protocol_extra: Used to tell the handler which python db engine
to use. For example one might want to tell
the sqlalchemy handler to use the psycopg2
python object.
handler: The handler used to build the orm object. Dodai
only works with sqlalchemy so the default 'sa'
is used.
"""
for name, section in sections.items():
self.connections[name] = DatabaseConnection(section, name,
self._handlers)
def load(self, section_name):
"""Returns a database connection object of the given section_name.
Throws Exceptions for any type of configuration errors or missing
configuration data
"""
if section_name in self.connections:
return self.connections[section_name].load()
else:
raise UnknownDatabaseConnectionException(section_name)
def add_handler(self, name, handler):
"""Adds the given handler and name to this objects handlers
"""
self._handlers[name] = handler
class DatabaseConnection(object):
DEFAULT_HANDLER = None
def __init__(self, section, name, handlers):
self.section = section
self.name = name
self.handlers = handlers
self.validate = DatabaseConnectionValidator.load(section, name)
self.obj = None
def load(self):
if not self.obj:
self.validate()
handler = self._get_handler()
self.obj = handler(self.section, self.name)
return self.obj
def _get_handler(self):
if self.section.has_key('handler'):
name = self.section['handler']
if name in self.handlers:
return self.handlers[name]
return self.handlers[self.DEFAULT_HANDLER]
class DatabaseConnectionValidator(object):
def __init__(self, section, name, validators=[]):
self.section = section
self.name = name
self.validators = validators
def __call__(self):
return self.validate()
def validate(self):
"""Validates the connection. Returns true if valid. Throws
DodaiDatabaseConnectionConfigurationError on any errors
"""
raise NotImplementedError()
def _validate_option(self, name):
try:
value = self.section[name]
except KeyError:
value = None
if not value:
raise DatabaseEmptyOptionException(self.name, name)
return True
def _validate_protocol(self):
self._validate_option('protocol')
if self.section['protocol'] not in self.PROTOCOLS:
raise DatabaseProtocolException(self.name,
self.section['protocol'], self.DB_TYPE,
self.PROTOCOLS)
return True
@staticmethod
def load(section, name):
"""Static method (factory) that loads the correct database
validation class.
Attributes:
section: Dictionary of key val connection information
name: String name of the section
"""
action = None
validators = [DatabaseConnectionValidatorServer,
DatabaseConnectionValidatorFile]
for validator in validators:
obj = validator.load(section, name)
if obj:
return obj
return DatabaseConnectionValidatorUnknown(section, name, validators)
class DatabaseConnectionValidatorServer(DatabaseConnectionValidator):
DB_TYPE = 'server'
REQUIRED = ['protocol', 'hostname', 'port', 'username', 'password',
'database']
PROTOCOLS = ['postgresql', 'mysql', 'mssql', 'oracle']
def _validate_port(self):
self._validate_option('port')
try:
port = int(self.section['port'])
except ValueError:
port = self.section['port']
else:
if port >=1 and port <=65535:
return True
raise DatabasePortException(self.name, port)
def validate(self):
"""Validates the connection. Returns true if valid. Throws
DodaiDatabaseConnectionConfigurationError on any errors
"""
self._validate_protocol()
self._validate_port()
self._validate_option('hostname')
self._validate_option('username')
self._validate_option('password')
self._validate_option('database')
return True
@classmethod
def load(cls, section, name):
"""Return this validation class if it is possible that the
given connection information contains enough data to make
a database server connection.
Attributes:
section: Dictionary of key val connection information
name: String name of the section
"""
if section.has_key('protocol'):
if section['protocol'] in cls.PROTOCOLS:
return cls(section, name)
keys = section.keys()
for key in keys:
if key in ['hostname', 'port']:
return cls(section, name)
class DatabaseConnectionValidatorFile(DatabaseConnectionValidator):
DB_TYPE = 'file'
REQUIRED = ['protocol', 'filename']
PROTOCOLS = ['sqlite']
def validate(self):
"""Validates the connection. Returns true if valid. Throws
DodaiDatabaseConnectionConfigurationError on any errors
"""
self._validate_protocol()
self._validate_option('filename')
return True
@classmethod
def load(cls, section, name):
"""Return this validation class if it is possible that the
given connection information contains enough data to make
a database file connection.
Attributes:
section: Dictionary of key val connection information
name: String name of the section
"""
if section.has_key('protocol'):
if section['protocol'] in cls.PROTOCOLS:
return cls(section, name)
keys = section.keys()
for key in keys:
if key in ['filename']:
return cls(section, name)
class DatabaseConnectionValidatorUnknown(DatabaseConnectionValidator):
DB_TYPE = 'unkonwn'
REQUIRED = []
PROTOCOLS = []
def validate(self):
"""Validates the connection. Returns true if valid. Throws
DodaiDatabaseConnectionConfigurationError on any errors
"""
raise DatabaseConnectionException(self.name, self.validators)
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