Source Code for Module recsql.sqlutil

 1  # $Id: sqlutil.py 2346 2008-10-06 19:36:21Z oliver $ 
 2  # Copyright (C) 2009 Oliver Beckstein <orbeckst@gmail.com> 
 3  # Released under the GNU Public License, version 3 or higher (your choice) 
 4   
 5  """ 
 6  :mod:`sqlutils` -- Helper functions 
 7  =================================== 
 8   
 9  Helper functions that are used throughout the :mod:`recsql` package. 
10   
11  How to use the sql converters and adapters: 
12     Declare types as 'NumpyArray':: 
13   
14        cur.execute("CREATE TABLE test(a NumpyArray)") 
15        cur.execute("INSERT INTO test(a) values (?)", (my_array,)) 
16   
17     or as column types:: 
18   
19        cur.execute('SELECT a as "a [NumpyArray]" from test') 
20   
21  Module content 
22  -------------- 
23  .. See the autogenerated content in the online docs or the source code. 
24  """ 
25   
26  import cPickle 
27   
28  # storing numpy arrays in the db as pickles 
29 -def adapt_numpyarray(a): 
30      """adapter: store numpy arrays in the db as ascii pickles""" 
31      return cPickle.dumps(a,protocol=0)  # must use text protocol for use with sqlite 
32   
33 -def convert_numpyarray(s): 
34      """converter: retrieve numpy arrays from the db as ascii pickles""" 
35      return cPickle.loads(s) 
36   
37 -def adapt_object(a): 
38      """adapter: store python objects in the db as ascii pickles""" 
39      return cPickle.dumps(a,protocol=0)  # must use text protocol for use with sqlite 
40   
41 -def convert_object(s): 
42      """convertor: retrieve python objects from the db as ascii pickles""" 
43      return cPickle.loads(s) 
44   
45   
46  # Fake* not needed anymore since SQLarray takes an iterable + columns descriptors 
47  # Use FakeRecArray to load the db from an iterable 
48   
49 -class FakeDtype(object): 
50 -    def __init__(self,**kwargs): 
51          self.__dict__.update(kwargs) 
52   
53 -class FakeRecArray(object): 
54      """Pseudo recarray that is used to feed SQLarray: 
55   
56      Must only implement: 
57   
58        recarray.dtype.names         sequence of column names 
59        iteration                    yield records 
60      """ 
61 -    def __init__(self, iterable, columns): 
62          self.dtype = FakeDtype(names=columns) 
63          self.iterable = iterable 
64   
65 -    def __iter__(self): 
66          for rec in self.iterable: 
67              yield rec 
68