162 lines
3.6 KiB
Python
162 lines
3.6 KiB
Python
"""
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by default, things are stored in a "shelf" table
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>>> d = SQLiteShelf("test.sdb")
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you can put multiple shelves into a single SQLite database
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>>> e = SQLiteShelf("test.sdb", "othertable")
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both are empty to start with
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>>> d
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{}
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>>> e
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{}
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adding stuff is as simple as a regular dict
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>>> d['a'] = "moo"
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>>> e['a'] = "moo"
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regular dict actions work
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>>> d['a']
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'moo'
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>>> e['a']
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'moo'
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>>> 'a' in d
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True
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>>> len(d)
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1
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>>> del d['a']
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>>> 'a' in d
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False
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>>> len(d)
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0
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>>> del e['a']
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objects can be stored in shelves
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>> class Test:
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.. def __init__(self):
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.. self.foo = "bar"
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..
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>> t = Test()
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>> d['t'] = t
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>> print d['t'].foo
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bar
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errors are as normal for a dict
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>>> d['x']
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Traceback (most recent call last):
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...
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KeyError: 'x'
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>>> del d['x']
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Traceback (most recent call last):
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...
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KeyError: 'x'
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Adding and fetching binary strings
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>>> d[1] = "a\\x00b"
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>>> d[1]
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'a\\x00b'
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"""
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try:
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from UserDict import DictMixin
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except ImportError:
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from collections import MutableMapping as DictMixin
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try:
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import cPickle as pickle
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except ImportError:
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import pickle
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import sys
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valtype = str
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if sys.version > '3':
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buffer = memoryview
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valtype = bytes
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import sqlite3
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class SQLiteDict(DictMixin):
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def __init__(self, filename=':memory:', table='shelf', flags='r', mode=None, valtype=valtype):
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self.table = table
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self.valtype = valtype
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MAKE_SHELF = 'CREATE TABLE IF NOT EXISTS '+self.table+' (key TEXT, value BLOB)'
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MAKE_INDEX = 'CREATE UNIQUE INDEX IF NOT EXISTS '+self.table+'_keyndx ON '+self.table+'(key)'
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self.conn = sqlite3.connect(filename)
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self.conn.text_factory = str
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self.conn.execute(MAKE_SHELF)
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self.conn.execute(MAKE_INDEX)
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self.conn.commit()
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def __getitem__(self, key):
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GET_ITEM = 'SELECT value FROM '+self.table+' WHERE key = ?'
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item = self.conn.execute(GET_ITEM, (key,)).fetchone()
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if item is None:
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raise KeyError(key)
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return self.valtype(item[0])
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def __setitem__(self, key, item):
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ADD_ITEM = 'REPLACE INTO '+self.table+' (key, value) VALUES (?,?)'
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self.conn.execute(ADD_ITEM, (key, sqlite3.Binary(item)))
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self.conn.commit()
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def __delitem__(self, key):
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if key not in self:
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raise KeyError(key)
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DEL_ITEM = 'DELETE FROM '+self.table+' WHERE key = ?'
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self.conn.execute(DEL_ITEM, (key,))
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self.conn.commit()
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def __iter__(self):
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c = self.conn.cursor()
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try:
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c.execute('SELECT key FROM '+self.table+' ORDER BY key')
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for row in c:
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yield row[0]
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finally:
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c.close()
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def keys(self):
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c = self.conn.cursor()
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try:
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c.execute('SELECT key FROM '+self.table+' ORDER BY key')
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return [row[0] for row in c]
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finally:
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c.close()
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###################################################################
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# optional bits
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def __len__(self):
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GET_LEN = 'SELECT COUNT(*) FROM '+self.table
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return self.conn.execute(GET_LEN).fetchone()[0]
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def close(self):
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if self.conn is not None:
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self.conn.commit()
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self.conn.close()
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self.conn = None
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def __del__(self):
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self.close()
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def __repr__(self):
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return repr(dict(self))
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class SQLiteShelf(SQLiteDict):
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def __getitem__(self, key):
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return pickle.loads(SQLiteDict.__getitem__(self, key))
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def __setitem__(self, key, item):
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SQLiteDict.__setitem__(self, key, pickle.dumps(item))
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if __name__ == "__main__":
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import doctest
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doctest.testmod()
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