python-mylib/mylib/mysql.py

""" MySQL client """

import logging
import sys

import MySQLdb
from MySQLdb._exceptions import Error

from mylib.db import DB, DBFailToConnect

log = logging.getLogger(__name__)


class MyDB(DB):
    """MySQL client"""

    _host = None
    _user = None
    _pwd = None
    _db = None

    def __init__(self, host, user, pwd, db, charset=None, **kwargs):
        self._host = host
        self._user = user
        self._pwd = pwd
        self._db = db
        self._charset = charset if charset else "utf8"
        super().__init__(**kwargs)

    def connect(self, exit_on_error=True):
        """Connect to MySQL server"""
        if self._conn is None:
            try:
                self._conn = MySQLdb.connect(
                    host=self._host,
                    user=self._user,
                    passwd=self._pwd,
                    db=self._db,
                    charset=self._charset,
                    use_unicode=True,
                )
            except Error as err:
                log.fatal(
                    "An error occurred during MySQL database connection (%s@%s:%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 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)
            cursor.execute(sql, params)
            self._conn.commit()
            return True
        except 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
        """
        try:
            self._log_query(sql, params)
            cursor = self._conn.cursor()
            cursor.execute(sql, params)
            return [
                {field[0]: row[idx] for idx, field in enumerate(cursor.description)}
                for row in cursor.fetchall()
            ]
        except Error:
            self._log_query_exception(sql, params)
        return False

    @staticmethod
    def _quote_table_name(table):
        """Quote table name"""
        return "`{}`".format(  # pylint: disable=consider-using-f-string
            "`.`".join(table.split("."))
        )

    @staticmethod
    def _quote_field_name(field):
        """Quote table name"""
        return f"`{field}`"