#!/usr/bin/env python3
# -*- coding: utf-8 -*-
#
# gPodder - A media aggregator and podcast client
# Copyright (c) 2005-2018 The gPodder Team
#
# gPodder is free software; you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation; either version 3 of the License, or
# (at your option) any later version.
#
# gPodder is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program. If not, see .
#
# gpodder.minidb - A simple SQLite store for Python objects
# Thomas Perl, 2010-01-28
# based on: "ORM wie eine Kirchenmaus - a very poor ORM implementation
# by thp, 2009-11-29 (thp.io/about)"
# This module is also available separately at:
# http://thp.io/2010/minidb/
# For Python 2.5, we need to request the "with" statement
try:
import sqlite3.dbapi2 as sqlite
except ImportError:
try:
from pysqlite2 import dbapi2 as sqlite
except ImportError:
raise Exception('Please install SQLite3 support.')
import threading
class Store(object):
def __init__(self, filename=':memory:'):
self.db = sqlite.connect(filename, check_same_thread=False)
self.lock = threading.RLock()
def _schema(self, class_):
return class_.__name__, list(sorted(class_.__slots__))
def _set(self, o, slot, value):
# Set a slot on the given object to value, doing a cast if
# necessary. The value None is special-cased and never cast.
cls = o.__class__.__slots__[slot]
if value is not None:
if isinstance(value, bytes):
value = value.decode('utf-8')
value = cls(value)
setattr(o, slot, value)
def commit(self):
with self.lock:
self.db.commit()
def close(self):
with self.lock:
self.db.isolation_level = None
self.db.execute('VACUUM')
self.db.isolation_level = ''
self.db.close()
def _register(self, class_):
with self.lock:
table, slots = self._schema(class_)
cur = self.db.execute('PRAGMA table_info(%s)' % table)
available = cur.fetchall()
if available:
available = [row[1] for row in available]
missing_slots = (s for s in slots if s not in available)
for slot in missing_slots:
self.db.execute('ALTER TABLE %s ADD COLUMN %s TEXT' % (table,
slot))
else:
self.db.execute('CREATE TABLE %s (%s)' % (table,
', '.join('%s TEXT' % s for s in slots)))
def convert(self, v):
if isinstance(v, str):
return v
elif isinstance(v, str):
# XXX: Rewrite ^^^ as "isinstance(v, bytes)" in Python 3
return v.decode('utf-8')
else:
return str(v)
def update(self, o, **kwargs):
self.remove(o)
for k, v in list(kwargs.items()):
setattr(o, k, v)
self.save(o)
def save(self, o):
if hasattr(o, '__iter__'):
klass = None
for child in o:
if klass is None:
klass = child.__class__
self._register(klass)
table, slots = self._schema(klass)
if not isinstance(child, klass):
raise ValueError('Only one type of object allowed')
used = [s for s in slots if getattr(child, s, None) is not None]
values = [self.convert(getattr(child, slot)) for slot in used]
self.db.execute('INSERT INTO %s (%s) VALUES (%s)' % (table,
', '.join(used), ', '.join('?' * len(used))), values)
return
with self.lock:
self._register(o.__class__)
table, slots = self._schema(o.__class__)
values = [self.convert(getattr(o, slot)) for slot in slots]
self.db.execute('INSERT INTO %s (%s) VALUES (%s)' % (table,
', '.join(slots), ', '.join('?' * len(slots))), values)
def delete(self, class_, **kwargs):
with self.lock:
self._register(class_)
table, slots = self._schema(class_)
sql = 'DELETE FROM %s' % (table,)
if kwargs:
sql += ' WHERE %s' % (' AND '.join('%s=?' % k for k in kwargs))
try:
self.db.execute(sql, list(kwargs.values()))
return True
except Exception as e:
return False
def remove(self, o):
if hasattr(o, '__iter__'):
for child in o:
self.remove(child)
return
with self.lock:
self._register(o.__class__)
table, slots = self._schema(o.__class__)
# Use "None" as wildcard selector in remove actions
slots = [s for s in slots if getattr(o, s, None) is not None]
values = [self.convert(getattr(o, slot)) for slot in slots]
self.db.execute('DELETE FROM %s WHERE %s' % (table,
' AND '.join('%s=?' % s for s in slots)), values)
def load(self, class_, **kwargs):
with self.lock:
self._register(class_)
table, slots = self._schema(class_)
sql = 'SELECT %s FROM %s' % (', '.join(slots), table)
if kwargs:
sql += ' WHERE %s' % (' AND '.join('%s=?' % k for k in kwargs))
try:
cur = self.db.execute(sql, list(kwargs.values()))
except Exception as e:
raise
def apply(row):
o = class_.__new__(class_)
for attr, value in zip(slots, row):
try:
self._set(o, attr, value)
except ValueError as ve:
return None
return o
return [x for x in [apply(row) for row in cur] if x is not None]
def get(self, class_, **kwargs):
result = self.load(class_, **kwargs)
if result:
return result[0]
else:
return None
if __name__ == '__main__':
class Person(object):
__slots__ = {'username': str, 'id': int}
def __init__(self, username, id):
self.username = username
self.id = id
def __repr__(self):
return '' % (self.username, self.id)
m = Store()
m.save(Person('User %d' % x, x * 20) for x in range(50))
p = m.get(Person, id=200)
print(p)
m.remove(p)
p = m.get(Person, id=200)
# Remove some persons again (deletion by value!)
m.remove(Person('User %d' % x, x * 20) for x in range(40))
class Person(object):
__slots__ = {'username': str, 'id': int, 'mail': str}
def __init__(self, username, id, mail):
self.username = username
self.id = id
self.mail = mail
def __repr__(self):
return '' % (self.username, self.mail)
# A schema update takes place here
m.save(Person('User %d' % x, x * 20, 'user@home.com') for x in range(50))
print(m.load(Person))