python-mylib/mylib/pgsql.py

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# -*- coding: utf-8 -*-
""" PostgreSQL client """
import datetime
import logging
import sys
import psycopg2
log = logging.getLogger(__name__)
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class PgDB:
""" PostgreSQL client """
host = ""
user = ""
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pwd = ""
db = ""
con = 0
date_format = '%Y-%m-%d'
datetime_format = '%Y-%m-%d %H:%M:%S'
def __init__(self, host, user, pwd, db, just_try=False):
self.host = host
self.user = user
self.pwd = pwd
self.db = db
self.just_try = just_try
def connect(self):
""" Connect to PostgreSQL server """
if self.con == 0:
try:
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con = psycopg2.connect(
dbname=self.db,
user=self.user,
host=self.host,
password=self.pwd
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)
self.con = con
except Exception:
logging.fatal(
'An error occured during Postgresql database connection (%s@%s, database=%s).',
self.user, self.host, self.db, exc_info=1
)
sys.exit(1)
return True
def close(self):
""" Close connection with PostgreSQL server (if opened) """
if self.con:
self.con.close()
def setEncoding(self, enc):
""" Set connection encoding """
if self.con:
try:
self.con.set_client_encoding(enc)
return True
except Exception:
log.error('An error occured setting Postgresql database connection encoding to "%s"', enc, exc_info=1)
return False
def doSQL(self, sql, params=None):
""" Run SELECT SQL query and return result as dict """
if self.just_try:
log.debug(u"Just-try mode : do not really execute SQL query '%s'", sql)
return True
cursor = self.con.cursor()
try:
if params is None:
cursor.execute(sql)
else:
cursor.execute(sql, params)
self.con.commit()
return True
except Exception:
log.error(u'Error during SQL request "%s"', sql.decode('utf-8', 'ignore'), exc_info=1)
self.con.rollback()
return False
def doSelect(self, sql):
""" Run SELECT SQL query and return result as dict """
cursor = self.con.cursor()
try:
cursor.execute(sql)
results = cursor.fetchall()
return results
except Exception:
log.error(u'Error during SQL request "%s"', sql.decode('utf-8', 'ignore'), exc_info=1)
return False
#
# SQL helpers
#
def _quote_value(self, value):
""" Quote a value for SQL query """
if isinstance(value, (int, float)):
return str(value)
if isinstance(value, datetime.datetime):
value = self._format_datetime(value)
elif isinstance(value, datetime.date):
value = self._format_date(value)
return u"'%s'" % value.replace(u"'", u"''")
def _format_where_clauses(self, where_clauses, where_op=u'AND'):
""" Format WHERE clauses """
if isinstance(where_clauses, str):
return where_clauses
if isinstance(where_clauses, list):
return (u" %s " % where_op).join(where_clauses)
if isinstance(where_clauses, dict):
return (u" %s " % where_op).join(map(lambda x: "%s=%s" % (x, self._quote_value(where_clauses[x])), where_clauses))
log.error('Unsupported where clauses type %s', type(where_clauses))
return False
def _format_datetime(self, value):
""" Format datetime object as string """
assert isinstance(value, datetime.datetime)
return value.strftime(self.datetime_format)
def _format_date(self, value):
""" Format date object as string """
assert isinstance(value, (datetime.date, datetime.datetime))
return value.strftime(self.date_format)
def time2datetime(self, time):
""" Convert timestamp to datetime string """
return self._format_datetime(datetime.datetime.fromtimestamp(int(time)))
def time2date(self, time):
""" Convert timestamp to date string """
return self._format_date(datetime.date.fromtimestamp(int(time)))
def insert(self, table, values, just_try=False):
""" Run INSERT SQL query """
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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:
log.debug(u"Just-try mode : execute INSERT query : %s", sql)
return True
log.debug(sql)
if not self.doSQL(sql):
log.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):
""" Run UPDATE SQL query """
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where = self._format_where_clauses(where_clauses, where_op=where_op)
if not where:
return False
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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:
log.debug(u"Just-try mode : execute UPDATE query : %s", sql)
return True
log.debug(sql)
if not self.doSQL(sql):
log.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):
""" Run DELETE SQL query """
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where = self._format_where_clauses(where_clauses, where_op=where_op)
if not where:
return False
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sql = u"DELETE FROM %s WHERE %s" % (table, where)
if just_try:
log.debug(u"Just-try mode : execute DELETE query : %s", sql)
return True
log.debug(sql)
if not self.doSQL(sql):
log.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):
""" Run SELECT SQL query """
sql = u"SELECT "
if fields is None:
sql += "*"
elif isinstance(fields, str):
sql += fields
else:
sql += u", ".join(fields)
sql += u" FROM " + table
if where_clauses:
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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)