python-mylib/mylib/pgsql.py

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# -*- coding: utf-8 -*-
""" PostgreSQL client """
import datetime
import logging
import sys
import psycopg2
from mylib.db import DB, DBFailToConnect
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log = logging.getLogger(__name__)
class PgDB(DB):
""" PostgreSQL client """
_host = None
_user = None
_pwd = None
_db = None
date_format = '%Y-%m-%d'
datetime_format = '%Y-%m-%d %H:%M:%S'
def __init__(self, host, user, pwd, db, **kwargs):
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self._host = host
self._user = user
self._pwd = pwd
self._db = db
super().__init__(**kwargs)
def connect(self, exit_on_error=True):
""" Connect to PostgreSQL server """
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if self._conn is None:
try:
log.info(
'Connect on PostgreSQL server %s as %s on database %s',
self._host, self._user, self._db)
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self._conn = psycopg2.connect(
dbname=self._db,
user=self._user,
host=self._host,
password=self._pwd
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)
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except psycopg2.Error as err:
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log.fatal(
'An error occured during Postgresql database connection (%s@%s, database=%s).',
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self._user, self._host, self._db, exc_info=1
)
if exit_on_error:
sys.exit(1)
else:
raise DBFailToConnect(f'{self._user}@{self._host}:{self._db}') from err
return True
def close(self):
""" Close connection with PostgreSQL server (if opened) """
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if self._conn:
self._conn.close()
self._conn = None
def setEncoding(self, enc):
""" Set connection encoding """
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if self._conn:
try:
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self._conn.set_client_encoding(enc)
return True
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except psycopg2.Error:
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log.error(
'An error occured setting Postgresql database connection encoding to "%s"',
enc, exc_info=1
)
return False
def doSQL(self, sql, params=None):
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"""
Run SQL query and commit changes (rollback on error)
:param sql: The SQL query
:param params: The SQL query's parameters as dict (optional)
:return: True on success, False otherwise
:rtype: bool
"""
if self.just_try:
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log.debug("Just-try mode : do not really execute SQL query '%s'", sql)
return True
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cursor = self._conn.cursor()
try:
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self._log_query(sql, params)
if params is None:
cursor.execute(sql)
else:
cursor.execute(sql, params)
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self._conn.commit()
return True
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except psycopg2.Error:
self._log_query_exception(sql, params)
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self._conn.rollback()
return False
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def doSelect(self, sql, params=None):
"""
Run SELECT SQL query and return list of selected rows as dict
:param sql: The SQL query
:param params: The SQL query's parameters as dict (optional)
:return: List of selected rows as dict on success, False otherwise
:rtype: list, bool
"""
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cursor = self._conn.cursor()
try:
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self._log_query(sql, params)
cursor.execute(sql, params)
results = cursor.fetchall()
return results
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except psycopg2.Error:
self._log_query_exception(sql, params)
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return False
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@staticmethod
def _map_row_fields_by_index(fields, row):
return dict(
(field, row[idx])
for idx, field in enumerate(fields)
)
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#
# Depreated helpers
#
@classmethod
def _quote_value(cls, value):
""" Quote a value for SQL query """
if value is None:
return 'NULL'
if isinstance(value, (int, float)):
return str(value)
if isinstance(value, datetime.datetime):
value = cls._format_datetime(value)
elif isinstance(value, datetime.date):
value = cls._format_date(value)
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# pylint: disable=consider-using-f-string
return "'{0}'".format(value.replace("'", "''"))
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@classmethod
def _format_datetime(cls, value):
""" Format datetime object as string """
assert isinstance(value, datetime.datetime)
return value.strftime(cls.datetime_format)
@classmethod
def _format_date(cls, value):
""" Format date object as string """
assert isinstance(value, (datetime.date, datetime.datetime))
return value.strftime(cls.date_format)
@classmethod
def time2datetime(cls, time):
""" Convert timestamp to datetime string """
return cls._format_datetime(datetime.datetime.fromtimestamp(int(time)))
@classmethod
def time2date(cls, time):
""" Convert timestamp to date string """
return cls._format_date(datetime.date.fromtimestamp(int(time)))