python-mylib/mylib/pgsql.py

# -*- coding: utf-8 -*-

""" PostgreSQL client """

import datetime
import logging
import sys

import psycopg2

from mylib.db import DB, DBFailToConnect

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):
        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 """
        if self._conn is None:
            try:
                log.info(
                    'Connect on PostgreSQL server %s as %s on database %s',
                    self._host, self._user, self._db)
                self._conn = psycopg2.connect(
                    dbname=self._db,
                    user=self._user,
                    host=self._host,
                    password=self._pwd
                )
            except psycopg2.Error as err:
                log.fatal(
                    'An error occured during Postgresql database connection (%s@%s, database=%s).',
                    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) """
        if self._conn:
            self._conn.close()
            self._conn = None

    def setEncoding(self, enc):
        """ Set connection encoding """
        if self._conn:
            try:
                self._conn.set_client_encoding(enc)
                return True
            except psycopg2.Error:
                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 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:
            log.debug("Just-try mode : do not really execute SQL query '%s'", sql)
            return True

        cursor = self._conn.cursor()
        try:
            self._log_query(sql, params)
            if params is None:
                cursor.execute(sql)
            else:
                cursor.execute(sql, params)
            self._conn.commit()
            return True
        except psycopg2.Error:
            self._log_query_exception(sql, params)
            self._conn.rollback()
            return False

    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
        """
        cursor = self._conn.cursor()
        try:
            self._log_query(sql, params)
            cursor.execute(sql, params)
            results = cursor.fetchall()
            return results
        except psycopg2.Error:
            self._log_query_exception(sql, params)
        return False

    @staticmethod
    def _map_row_fields_by_index(fields, row):
        return dict(
            (field, row[idx])
            for idx, field in enumerate(fields)
        )

    #
    # 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)

        # pylint: disable=consider-using-f-string
        return "'{0}'".format(value.replace("'", "''"))

    @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)))