sqlobject-discuss

[SQLObject] Pickling

[Philippe N. <ph...@re...>]

Hi,

I'm currently having the following issue when trying to pickle SQLObjects
(0.5.2) / python 2.2:

-------------------------------------------------------------------------

from cPickle import dump, load


class SessionTest:

    def __init__(self, val):
        self._dict = {'row': val}


# get an SQLObject with id == 1
a = Alinea_getArticleWithID(1)
test = SessionTest(a)

f = open('toto','w')
dump(test,f)
f.close()
print open('toto').read()
-------------------------------------------------------------------------

    dump(test,f)
cPickle.UnpickleableError: Cannot pickle <type 'thread.lock'> objects


Has anybody succeeded pickling SQLObjects ?

Cheers,

PS: I'm not subscribed to the list, please reply to ph...@re...

--
PN

Re: [SQLObject] Pickling

[charles b. <li...@st...>]

Hi Philippe,

I'm pretty new to SQLObject, but I also just ran into this issue.  I was
using pickle(shelve) as a temporary way to add persistence to dict type
session data in quixote, and wanted to associate a SQLObject with the
session.

This is just a guess, but it makes sense on a conceptual level that pickle
should not allow storing data related to thread dependent objects (like
SQLObjects).  There is no guarantee that the process associated with an
object will still exist when the pickled data is unpickled (the whole point
of pickling anyway... persisting across processes).  For SQLObjects
specifically, there are database connections associated with the object.

I then realized that pickle and databases are both ways to add persistence
to data.  Therefore, whatever data you are trying to persist using pickle,
you may just want to persist using SQLObject.

Now if only I could figure out a way to easily map an existing dict type
object to a SQLObject I'd be set.  Anyone else have experience/advice on
doing that??

> PS: I'm not subscribed to the list, please reply to ph...@re...
Why not join?  Wouldn't want you to miss other responses... ;)

-Charles.

[SQLObject] DBconnection SQL generation error?

[charles b. <li...@st...>]

I think there might be a problem with the way DBConnection generates some
SQL queries.  Specifically, when using SQLObject's createTable function on a
table with a column named "key", mysql will throw an exception since the
generated SQL does not back quote the names of items.

CREATE TABLE table_name (
    id INT PRIMARY KEY AUTO_INCREMENT,
    value VARCHAR(255) NOT NULL UNIQUE,
    key VARCHAR(255) NOT NULL UNIQUE
)

should probably be:

CREATE TABLE `table_name` (
    `id` INT PRIMARY KEY AUTO_INCREMENT,
    `value` VARCHAR(255) NOT NULL UNIQUE,
    `key` VARCHAR(255) NOT NULL UNIQUE
)

I haven't had a chance to investigate further, but I wanted to throw it out
there before I forgot.  Thanks!

-Charles

Re: [SQLObject] Pickling

[Ian B. <ia...@co...>]

On Mar 21, 2004, at 5:34 PM, Philippe Normand wrote:
> I'm currently having the following issue when trying to pickle 
> SQLObjects
> (0.5.2) / python 2.2:

SQLObject doesn't currently support pickling, though I believe the 
changes necessary would not be particularly difficult -- adding a 
__getinitargs__ (or something like that, the pickle docs have more) 
would probably do it.  (Adding to both SQLObject and DBConnection 
objects)

--
Ian Bicking | ia...@co... | http://blog.ianbicking.org