Anki/pylib/anki/dbproxy.py
Damien Elmes 7ac1fa17e6 move proto files into separate py_library in same namespace
Will allow importing the Protobuf without pulling in the rest of
the library. This is not a full PEP420 namespace, and the wheel still
bundles everything - it just makes things easier in a Bazel workspace.
I originally tried with PEP420, but it required more invasive changes,
and I ran into issues with mypy.
2021-07-11 14:51:25 +10:00

124 lines
3.5 KiB
Python

# Copyright: Ankitects Pty Ltd and contributors
# License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
from __future__ import annotations
import re
from re import Match
from typing import Any, Dict, Iterable, List, Optional, Sequence, Tuple, Union
import anki._backend
# DBValue is actually Union[str, int, float, None], but if defined
# that way, every call site needs to do a type check prior to using
# the return values.
ValueFromDB = Any
Row = Sequence[ValueFromDB]
ValueForDB = Union[str, int, float, None]
class DBProxy:
# Lifecycle
###############
def __init__(self, backend: anki._backend.RustBackend) -> None:
self._backend = backend
self.modified_in_python = False
self.last_begin_at = 0
# Transactions
###############
def begin(self) -> None:
self.last_begin_at = self.scalar("select mod from col")
self._backend.db_begin()
def commit(self) -> None:
self._backend.db_commit()
def rollback(self) -> None:
self._backend.db_rollback()
# Querying
################
def _query(
self,
sql: str,
*args: ValueForDB,
first_row_only: bool = False,
**kwargs: ValueForDB,
) -> List[Row]:
# mark modified?
s = sql.strip().lower()
for stmt in "insert", "update", "delete":
if s.startswith(stmt):
self.modified_in_python = True
sql, args2 = emulate_named_args(sql, args, kwargs)
# fetch rows
return self._backend.db_query(sql, args2, first_row_only)
# Query shortcuts
###################
def all(self, sql: str, *args: ValueForDB, **kwargs: ValueForDB) -> List[Row]:
return self._query(sql, *args, first_row_only=False, **kwargs)
def list(
self, sql: str, *args: ValueForDB, **kwargs: ValueForDB
) -> List[ValueFromDB]:
return [x[0] for x in self._query(sql, *args, first_row_only=False, **kwargs)]
def first(self, sql: str, *args: ValueForDB, **kwargs: ValueForDB) -> Optional[Row]:
rows = self._query(sql, *args, first_row_only=True, **kwargs)
if rows:
return rows[0]
else:
return None
def scalar(self, sql: str, *args: ValueForDB, **kwargs: ValueForDB) -> ValueFromDB:
rows = self._query(sql, *args, first_row_only=True, **kwargs)
if rows:
return rows[0][0]
else:
return None
# execute used to return a pysqlite cursor, but now is synonymous
# with .all()
execute = all
# Updates
################
def executemany(self, sql: str, args: Iterable[Sequence[ValueForDB]]) -> None:
self.modified_in_python = True
if isinstance(args, list):
list_args = args
else:
list_args = list(args)
self._backend.db_execute_many(sql, list_args)
# convert kwargs to list format
def emulate_named_args(
sql: str, args: Tuple, kwargs: Dict[str, Any]
) -> Tuple[str, Sequence[ValueForDB]]:
# nothing to do?
if not kwargs:
return sql, args
print("named arguments in queries will go away in the future:", sql)
# map args to numbers
arg_num = {}
args2 = list(args)
for key, val in kwargs.items():
args2.append(val)
n = len(args2)
arg_num[key] = n
# update refs
def repl(m: Match) -> str:
arg = m.group(1)
return f"?{arg_num[arg]}"
sql = re.sub(":([a-zA-Z_0-9]+)", repl, sql)
return sql, args2