python-mylib/mylib/db.py

411 lines
13 KiB
Python

""" 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 occurred 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 DBInvalidLimitClause(DBException, TypeError):
"""
Raised when trying to select on table with invalid
LIMIT clause provided
"""
def __init__(self, limit):
super().__init__(
"Invalid LIMIT clause: {limit}. Must be a non-zero positive integer.",
limit=limit,
)
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 = {}".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 = {}".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 '"{}"'.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 {} ({}) VALUES ({})".format( # nosec
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 {} SET {}".format( # nosec
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)}" # nosec
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)}" # nosec
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,
limit=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 limit:
if not isinstance(limit, int):
try:
limit = int(limit)
except ValueError as err:
raise DBInvalidLimitClause(limit) from err
if limit <= 0:
raise DBInvalidLimitClause(limit)
sql += f" LIMIT {limit}"
if just_try:
log.debug("Just-try mode: execute SELECT query : %s", sql)
return just_try
return self.doSelect(sql, params=params)