python calling def __init__(self, uri=None): method

Question

I am working on python plugins for QGIS. I have my QueryBuilder.py and postgis.py files. I connected it to database using Connection class and under def __init__(self, uri=None) in postgis.py file. I want to connect to database through QueryBuilder.py file.I imported postgis.py into QueryBuilder.py But how to call def __init__(self, uri=None) of postgis.py from QueryBuilder.py? I need to create instance of 'Connection' class in order to call def __init__(self, uri=None) method of postgis.py in QueryBuilder.py How do I go about it?

postgis.py file:

class Connection(DbConn.Connection):

@classmethod
def getTypeName(self):
    return 'postgis'

@classmethod
def getTypeNameString(self):
    return 'PostgreSQL'

@classmethod
def getProviderName(self):
    return 'postgres'

@classmethod
def getSettingsKey(self):
    return 'PostgreSQL'

@classmethod
def icon(self):
    return QIcon(":/icons/postgis_elephant.png")

@classmethod


def __init__(self, uri=None):

    DbConn.Connection.__init__(self, uri)

    #self.host = uri.host()
    #self.port = uri.port()
    #self.dbname = uri.database()
    #self.user = uri.username()
    #self.passwd = uri.password()



    self.host ='localhost' 
    self.port =5432 
    self.dbname ='ssss'
    self.user = 'j'
    self.passwd = 'jkj'


    if self.dbname == '' or self.dbname is None:
        self.dbname = self.user

    try:
        self.con = psycopg2.connect(self.con_info())
    except psycopg2.OperationalError, e:
        raise DbError(e)

    self.has_spatial = self.check_spatial()

    self.check_geometry_columns_table()

    # a counter to ensure that the cursor will be unique
    self.last_cursor_id = 0
               '''
               '''
if __name__ == "__main__":
window = Connection()

and QueryBuilder.py is:

import sys
import pdb

from PyQt4 import QtGui, QtCore
import psycopg2
import pprint


#from qgis.core import *
#from qgis.gui import *


import postgis

from DatabaseModel import TableItem, SchemaItem, DatabaseModel
import DbConnection

from ui.DlgQueryBuilder_ui import Ui_Dialog
from DlgDbError import DlgDbError

from QueryParser import QueryParser
from QueryManager import *

class DlgQueryBuilder(QDialog, Ui_Dialog):
    so on.....

Answer 1

This should work:

in QueryBuilder.py

import postgis
conn = postgis.Connection()

or

from postgis import Connection
conn = Connection()