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server connection. The BaseDriver and BaseConnection are two abstract classes, which allows us to replace the existing driver with the currently used. The current implementation supports to connect the PostgreSQL and Postgres Plus Advanced Server using the psycopg2 driver.
153 lines
4.2 KiB
Python
153 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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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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__metaclass__ = DriverRegistry
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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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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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__metaclass__ = ABCMeta
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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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