python-mylib/mylib/db.py

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# -*- coding: utf-8 -*-
""" Basic SQL DB client """
import logging
log = logging.getLogger(__name__)
#
# Exceptions
#
class DBException(Exception):
""" That is the base exception class for all the other exceptions provided by this module. """
def __init__(self, error, *args, **kwargs):
for arg, value in kwargs.items():
setattr(self, arg, value)
super().__init__(error.format(*args, **kwargs))
class DBNotImplemented(DBException, RuntimeError):
"""
Raised when calling a method not implemented in child class
"""
def __init__(self, method, class_name):
super().__init__(
"The method {method} is not yet implemented in class {class_name}",
method=method, class_name=class_name
)
class DBFailToConnect(DBException, RuntimeError):
"""
Raised on connecting error occurred
"""
def __init__(self, uri):
super().__init__(
"An error occured during database connection ({uri})",
uri=uri
)
class DBDuplicatedSQLParameter(DBException, KeyError):
"""
Raised when trying to set a SQL query parameter
and an other parameter with the same name is already set
"""
def __init__(self, parameter_name):
super().__init__(
"Duplicated SQL parameter '{parameter_name}'",
parameter_name=parameter_name
)
class DBUnsupportedWHEREClauses(DBException, TypeError):
"""
Raised when trying to execute query with unsupported
WHERE clauses provided
"""
def __init__(self, where_clauses):
super().__init__(
"Unsupported WHERE clauses: {where_clauses}",
where_clauses=where_clauses
)
class DBInvalidOrderByClause(DBException, TypeError):
"""
Raised when trying to select on table with invalid
ORDER BY clause provided
"""
def __init__(self, order_by):
super().__init__(
"Invalid ORDER BY clause: {order_by}. Must be a string or a list of two values (ordering field name and direction)",
order_by=order_by
)
class DB:
""" Database client """
just_try = False
def __init__(self, just_try=False, **kwargs):
self.just_try = just_try
self._conn = None
for arg, value in kwargs.items():
setattr(self, f'_{arg}', value)
def connect(self, exit_on_error=True):
""" Connect to DB server """
raise DBNotImplemented('connect', self.__class__.__name__)
def close(self):
""" Close connection with DB server (if opened) """
if self._conn:
self._conn.close()
self._conn = None
@staticmethod
def _log_query(sql, params):
log.debug(
'Run SQL query "%s" %s',
sql,
"with params = {0}".format( # pylint: disable=consider-using-f-string
', '.join([
f'{key} = {value}'
for key, value in params.items()
]) if params else "without params"
)
)
@staticmethod
def _log_query_exception(sql, params):
log.exception(
'Error during SQL query "%s" %s',
sql,
"with params = {0}".format( # pylint: disable=consider-using-f-string
', '.join([
f'{key} = {value}'
for key, value in params.items()
]) if params else "without params"
)
)
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
"""
raise DBNotImplemented('doSQL', self.__class__.__name__)
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
"""
raise DBNotImplemented('doSelect', self.__class__.__name__)
#
# SQL helpers
#
@staticmethod
def _quote_table_name(table):
""" Quote table name """
return '"{0}"'.format( # pylint: disable=consider-using-f-string
'"."'.join(
table.split('.')
)
)
@staticmethod
def _quote_field_name(field):
""" Quote table name """
return f'"{field}"'
@staticmethod
def format_param(param):
""" Format SQL query parameter for prepared query """
return f'%({param})s'
@classmethod
def _combine_params(cls, params, to_add=None, **kwargs):
if to_add:
assert isinstance(to_add, dict), "to_add must be a dict or None"
params = cls._combine_params(params, **to_add)
for param, value in kwargs.items():
if param in params:
raise DBDuplicatedSQLParameter(param)
params[param] = value
return params
@classmethod
def _format_where_clauses(cls, where_clauses, params=None, where_op=None):
"""
Format WHERE clauses
:param where_clauses: The WHERE clauses. Could be:
- a raw SQL WHERE clause as string
- a tuple of two elements: a raw WHERE clause and its parameters as dict
- a dict of WHERE clauses with field name as key and WHERE clause value as value
- a list of any of previous valid WHERE clauses
:param params: Dict of other already set SQL query parameters (optional)
:param where_op: SQL operator used to combine WHERE clauses together (optional, default: AND)
:return: A tuple of two elements: raw SQL WHERE combined clauses and parameters on success
:rtype: string, bool
"""
if params is None:
params = {}
if where_op is None:
where_op = 'AND'
if isinstance(where_clauses, str):
return (where_clauses, params)
if isinstance(where_clauses, tuple) and len(where_clauses) == 2 and isinstance(where_clauses[1], dict):
cls._combine_params(params, where_clauses[1])
return (where_clauses[0], params)
if isinstance(where_clauses, (list, tuple)):
sql_where_clauses = []
for where_clause in where_clauses:
sql2, params = cls._format_where_clauses(where_clause, params=params, where_op=where_op)
sql_where_clauses.append(sql2)
return (
f' {where_op} '.join(sql_where_clauses),
params
)
if isinstance(where_clauses, dict):
sql_where_clauses = []
for field, value in where_clauses.items():
param = field
if field in params:
idx = 1
while param in params:
param = f'{field}_{idx}'
idx += 1
cls._combine_params(params, {param: value})
sql_where_clauses.append(
f'{cls._quote_field_name(field)} = {cls.format_param(param)}'
)
return (
f' {where_op} '.join(sql_where_clauses),
params
)
raise DBUnsupportedWHEREClauses(where_clauses)
@classmethod
def _add_where_clauses(cls, sql, params, where_clauses, where_op=None):
"""
Add WHERE clauses to an SQL query
:param sql: The SQL query to complete
:param params: The dict of parameters of the SQL query to complete
:param where_clauses: The WHERE clause (see _format_where_clauses())
:param where_op: SQL operator used to combine WHERE clauses together (optional, default: see _format_where_clauses())
:return:
:rtype: A tuple of two elements: raw SQL WHERE combined clauses and parameters
"""
if where_clauses:
sql_where, params = cls._format_where_clauses(where_clauses, params=params, where_op=where_op)
sql += " WHERE " + sql_where
return (sql, params)
def insert(self, table, values, just_try=False):
""" Run INSERT SQL query """
# pylint: disable=consider-using-f-string
sql = 'INSERT INTO {0} ({1}) VALUES ({2})'.format(
self._quote_table_name(table),
', '.join([
self._quote_field_name(field)
for field in values.keys()
]),
", ".join([
self.format_param(key)
for key in values
])
)
if just_try:
log.debug("Just-try mode: execute INSERT query: %s", sql)
return True
log.debug(sql)
if not self.doSQL(sql, params=values):
log.error("Fail to execute INSERT query (SQL: %s)", sql)
return False
return True
def update(self, table, values, where_clauses, where_op=None, just_try=False):
""" Run UPDATE SQL query """
# pylint: disable=consider-using-f-string
sql = 'UPDATE {0} SET {1}'.format(
self._quote_table_name(table),
", ".join([
f'{self._quote_field_name(key)} = {self.format_param(key)}'
for key in values
])
)
params = values
try:
sql, params = self._add_where_clauses(sql, params, where_clauses, where_op=where_op)
except (DBDuplicatedSQLParameter, DBUnsupportedWHEREClauses):
log.error('Fail to add WHERE clauses', exc_info=True)
return False
if just_try:
log.debug("Just-try mode: execute UPDATE query: %s", sql)
return True
log.debug(sql)
if not self.doSQL(sql, params=params):
log.error("Fail to execute UPDATE query (SQL: %s)", sql)
return False
return True
def delete(self, table, where_clauses, where_op='AND', just_try=False):
""" Run DELETE SQL query """
sql = f'DELETE FROM {self._quote_table_name(table)}'
params = {}
try:
sql, params = self._add_where_clauses(sql, params, where_clauses, where_op=where_op)
except (DBDuplicatedSQLParameter, DBUnsupportedWHEREClauses):
log.error('Fail to add WHERE clauses', exc_info=True)
return False
if just_try:
log.debug("Just-try mode: execute UPDATE query: %s", sql)
return True
log.debug(sql)
if not self.doSQL(sql, params=params):
log.error("Fail to execute UPDATE query (SQL: %s)", sql)
return False
return True
def truncate(self, table, just_try=False):
""" Run TRUNCATE SQL query """
sql = f'TRUNCATE TABLE {self._quote_table_name(table)}'
if just_try:
log.debug("Just-try mode: execute TRUNCATE query: %s", sql)
return True
log.debug(sql)
if not self.doSQL(sql):
log.error("Fail to execute TRUNCATE query (SQL: %s)", sql)
return False
return True
def select(self, table, where_clauses=None, fields=None, where_op='AND', order_by=None, just_try=False):
""" Run SELECT SQL query """
sql = "SELECT "
if fields is None:
sql += "*"
elif isinstance(fields, str):
sql += f'{self._quote_field_name(fields)}'
else:
sql += ', '.join([self._quote_field_name(field) for field in fields])
sql += f' FROM {self._quote_table_name(table)}'
params = {}
try:
sql, params = self._add_where_clauses(sql, params, where_clauses, where_op=where_op)
except (DBDuplicatedSQLParameter, DBUnsupportedWHEREClauses):
log.error('Fail to add WHERE clauses', exc_info=True)
return False
if order_by:
if isinstance(order_by, str):
sql += f' ORDER BY {order_by}'
elif (
isinstance(order_by, (list, tuple)) and len(order_by) == 2
and isinstance(order_by[0], str)
and isinstance(order_by[1], str)
and order_by[1].upper() in ('ASC', 'UPPER')
):
sql += f' ORDER BY "{order_by[0]}" {order_by[1].upper()}'
else:
raise DBInvalidOrderByClause(order_by)
if just_try:
log.debug("Just-try mode: execute SELECT query : %s", sql)
return just_try
return self.doSelect(sql, params=params)