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152 lines
4.2 KiB
Python
152 lines
4.2 KiB
Python
##########################################################################
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#
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# pgAdmin 4 - PostgreSQL Tools
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#
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# Copyright (C) 2013 - 2015, The pgAdmin Development Team
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# This software is released under the PostgreSQL Licence
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#
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##########################################################################
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from abc import ABCMeta, abstractmethod, abstractproperty
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from flask import session
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from .registry import DriverRegistry
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import six
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@six.add_metaclass(DriverRegistry)
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class BaseDriver(object):
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"""
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class BaseDriver(object):
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This is a base class for different server types.
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Inherit this class to implement different type of database driver
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implementation.
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(For PostgreSQL/Postgres Plus Advanced Server, we will be using psycopg2)
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Abstract Properties:
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-------- ----------
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* Version (string):
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Current version string for the database server
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Abstract Methods:
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-------- -------
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* get_connection(*args, **kwargs)
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- It should return a Connection class object, which may/may not be
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connected to the database server.
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* release_connection(*args, **kwargs)
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- Implement the connection release logic
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* gc()
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- Implement this function to release the connections assigned in the
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session, which has not been pinged from more than the idle timeout
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configuration.
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"""
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@abstractproperty
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def Version(cls):
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pass
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@abstractmethod
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def get_connection(self, *args, **kwargs):
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pass
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@abstractmethod
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def release_connection(self, *args, **kwargs):
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pass
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@abstractmethod
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def gc(self):
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pass
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@six.add_metaclass(ABCMeta)
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class BaseConnection(object):
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"""
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class BaseConnection(object)
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It is a base class for database connection. A different connection
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drive must implement this to expose abstract methods for this server.
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General idea is to create a wrapper around the actaul driver
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implementation. It will be instantiated by the driver factory
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basically. And, they should not be instantiated directly.
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Abstract Methods:
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-------- -------
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* connect(**kwargs)
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- Define this method to connect the server using that particular driver
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implementation.
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* execute_scalar(query, params)
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- Implement this method to execute the given query and returns single
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datum result.
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* execute_2darray(query, params)
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- Implement this method to execute the given query and returns the result
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as a 2 dimentional array.
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* execute_dict(query, params)
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- Implement this method to execute the given query and returns the result
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as an array of dict (column name -> value) format.
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* connected()
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- Implement this method to get the status of the connection. It should
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return True for connected, otherwise False
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* reset()
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- Implement this method to reconnect the database server (if possible)
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* transaction_status()
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- Implement this method to get the transaction status for this
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connection. Range of return values different for each driver type.
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* ping()
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- Implement this method to ping the server. There are times, a connection
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has been lost, but - the connection driver does not know about it. This
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can be helpful to figure out the actual reason for query failure.
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* _release()
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- Implement this method to release the connection object. This should not
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be directly called using the connection object itself.
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NOTE: Please use BaseDriver.release_connection(...) for releasing the
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connection object for better memory management, and connection pool
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management.
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"""
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@abstractmethod
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def connect(self, **kwargs):
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pass
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@abstractmethod
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def execute_scalar(self, query, params=None):
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pass
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@abstractmethod
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def execute_2darray(self, query, params=None):
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pass
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@abstractmethod
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def execute_dict(self, query, params=None):
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pass
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@abstractmethod
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def connected(self):
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pass
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@abstractmethod
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def reset(self):
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pass
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@abstractmethod
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def transaction_status(self):
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pass
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@abstractmethod
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def ping(self):
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pass
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@abstractmethod
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def _release(self):
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pass
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