[issue13299] namedtuple row factory for sqlite3

[Raymond Hettinger]

Raymond Hettinger added the comment:

Caching based on the cursor going to be problematic because a single cursor can be used multiple times with different descriptions:

   c = conn.cursor()
   c.execute('select symbol from stocks')
   print c.description
   c.execute('select price from stocks')
   print c.description     # same cursor, different layout, needs a new named tuple

It might make more sense to cache the namedtuple() factory itself:

   sql_namedtuple = lru_cache(maxsize=20)(namedtuple)

Also, the example in the docs is too lengthy and indirect.  Cut-out the step for creating an populating the database -- just assume db created in the example at the top of the page:

   For example::

    >>> conn.row_factory = sqlite3.NamedTupleRow
    >>> c = conn.cursor()
    >>> for record in c.execute('select * from stocks'):
            print record

    Row(date='2006-01-05', trans='BUY', symbol='RHAT', qty=100.0, price=35.14)
    Row(date='2006-01-05', trans='BUY', symbol='RHAT', qty=100, price=35.14)
    Row(date='2006-03-28', trans='BUY', symbol='IBM', qty=1000, price-45.0)

No need to go into a further lesson on how to use named tuples.


Also, the patch uses star-unpacking:  _namedtuple_row(cursor)(*row)

Instead, it should use _make:  _namedtuple_row(cursor)._make(row)


(u'2006-04-05', u'BUY', u'MSFT', 1000, 72.0)

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Python tracker <report at bugs.python.org>
<http://bugs.python.org/issue13299>
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