python-mylib/PgDB.py

#!/usr/bin/python
# -*- coding: utf-8 -*-

import psycopg2
import logging
import sys
import traceback
import datetime

class PgDB(object):

	host = ""
	user = ""
	pwd  = ""
	db   = ""

	con = 0

	date_format = '%Y-%m-%d'
	datetime_format = '%Y-%m-%d %H:%M:%S'

	def __init__(self,host,user,pwd,db):
		self.host = host
		self.user = user
		self.pwd  = pwd
		self.db   = db

	def connect(self):
		if self.con == 0:
			try:
				con = psycopg2.connect("dbname='%s' user='%s' host='%s' password='%s'" % (self.db,self.user,self.host,self.pwd))
				self.con = con
			except Exception:
				logging.fatal('An error occured during Postgresql database connection.', exc_info=1)
				sys.exit(1)

	def close(self):
		if self.con:
			self.con.close()

	def setEncoding(self,enc):
		if self.con:
			try:
				self.con.set_client_encoding(enc)
				return True
			except Exception:
				logging.error('An error occured setting Postgresql database connection encoding to "%s"', enc, exc_info=1)
		return False

	def doSQL(self,sql,params=None):
		cursor = self.con.cursor()
		try:
			if params is None:
				cursor.execute(sql)
			else:
				cursor.execute(sql,params)
			self.con.commit()
			return True
		except Exception:
			logging.error(u'Error during SQL request "%s"', sql.decode('utf-8', 'ignore'), exc_info=1)
			self.con.rollback()
			return False

	def doSelect(self,sql):
		cursor = self.con.cursor()
		try:
			cursor.execute(sql)
			results = cursor.fetchall()
			return results
		except Exception:
			logging.error(u'Error during SQL request "%s"', sql.decode('utf-8', 'ignore'), exc_info=1)
			return False

	#
	# SQL helpers
	#
	def _quote_value(self, value):
		if isinstance(value, int) or isinstance(value, float):
			return unicode(value)

		if isinstance(value, str):
			value = unicode(value)
		elif isinstance(value, datetime.datetime):
			value = unicode(self._format_datetime(value))
		elif isinstance(value, datetime.date):
			value = unicode(self._format_date(value))

		return u"'%s'" % value.replace(u"'",u"''")

	def _format_where_clauses(self, where_clauses, where_op=u'AND'):
		if isinstance(where_clauses, str):
			return where_clauses
		elif isinstance(where_clauses, list):
			return (u" %s " % where_op).join(where_clauses)
		elif isinstance(where_clauses, dict):
			return (u" %s " % where_op).join(map(lambda x: "%s=%s" % (x, self._quote_value(where_clauses[x])), where_clauses))
		logging.error('Unsupported where clauses type %s', type(where_clauses))
		return False

	def _format_datetime(self, datetime):
		return datetime.strftime(self.datetime_format)

	def _format_date(self, date):
		return date.strftime(self.date_format)

	def time2datetime(self, time):
		return self._format_datetime(datetime.fromtimestamp(int(time)))

	def time2date(self, time):
		return self._format_date(datetime.fromtimestamp(int(time)))

	def insert(self, table, values, just_try=False):
		sql=u"INSERT INTO %s (%s) VALUES (%s)" % (table, u', '.join(values.keys()), u", ".join(map(lambda x: self._quote_value(values[x]), values)))

		if just_try:
			logging.debug(u"Just-try mode : execute INSERT query : %s", sql)
			return True

		logging.debug(sql)
		if not self.doSQL(sql):
			logging.error(u"Fail to execute INSERT query (SQL : %s)" % sql)
			return False
		return True

	def update(self, table, values, where_clauses, where_op=u'AND', just_try=False):
		where=self._format_where_clauses(where_clauses, where_op=where_op)
		if not where:
			return False

		sql=u"UPDATE %s SET  %s WHERE %s" % (table, u", ".join(map(lambda x: "%s=%s" % (x, self._quote_value(values[x])), values)), where)

		if just_try:
			logging.debug(u"Just-try mode : execute UPDATE query : %s", sql)
			return True

		logging.debug(sql)
		if not self.doSQL(sql):
			logging.error(u"Fail to execute UPDATE query (SQL : %s)", sql)
			return False
		return True

	def delete(self, table, where_clauses, where_op=u'AND', just_try=False):
		where=self._format_where_clauses(where_clauses, where_op=where_op)
		if not where:
			return False

		sql=u"DELETE FROM %s WHERE %s" % (table, where)

		if just_try:
			logging.debug(u"Just-try mode : execute DELETE query : %s", sql)
			return True

		logging.debug(sql)
		if not self.doSQL(sql):
			logging.error(u"Fail to execute DELETE query (SQL : %s)", sql)
			return False
		return True

	def select(self, table, where_clauses=None, fields=None, where_op=u'AND', order_by=None, just_try=False):
		sql = u"SELECT "
		if fields is None:
			sql += "*"
		elif isinstance(fields, str) or isinstance(fields, unicode):
			sql += fields
		else:
			sql += u", ".join(fields)

		sql += u" FROM " + table
		if where_clauses:
			where=self._format_where_clauses(where_clauses, where_op=where_op)
			if not where:
				return False

			sql += u" WHERE " + where

		if order_by:
			sql += u"ORDER %s" % order_by

		return self.doSelect(sql)