[Twisted-Python] SQL, Threaded, and flows

[Edmund Dengler]

Added the import line, changed to query line to:

    query = Threaded(QueryIterator(dbpool, sql))

It now executes (no exceptions), but nothing is returned/printed. I am
obviously missing something, but I don't know enough of the internals
to hazard a guess as to what.

I am currently using the Aug 5 CVS tip.

Regards!
Ed

On Sat, 9 Aug 2003, Clark C. Evans wrote:

> Edmund,
>
>    This has been fixed in the CVS repository.  In short, when flow
>    was added into twisted, the "threaded" stuff seemed to be not
>    totally stable and really not core (as it is more useful with an
>    async Database or LDAP driver).  Thus, QueryIterator and Threaded
>    arn't imported into the flow module automatically as the example
>    assumed.  You can get to these two classes via:
>
>       from twisted.flow.threads import QueryIterator, Threaded
>
>    And then the example should mostly work from there.  Although
>    you do need an actual database connection, of course.
>
> Best,
>
> Clark
>
> [1] http://twistedmatrix.com/users/jh.twistd/viewcvs/cgi/viewcvs.cgi/doc/howto/flow.html?rev=HEAD&content-type=text/vnd.viewcvs-markup&cvsroot=Twisted
>
> On Sat, Aug 09, 2003 at 04:35:24PM -0400, Edmund Dengler wrote:
> | Hi all!
> |
> | I am trying the example from the Flow HowTo page, and I have into an
> | exception.
> |
> | ===========================
> |
> | from __future__         import generators
> | from twisted.enterprise import adbapi
> | from twisted.internet   import reactor
> | from twisted.flow import flow
> |
> | dbpool = adbapi.ConnectionPool("SomeDriver",host='localhost',
> |              db='Database',user='User',passwd='Password')
> |
> | sql = """
> |   (SELECT 'one')
> | UNION ALL
> |   (SELECT 'two')
> | UNION ALL
> |   (SELECT 'three')
> | """
> |
> | def consumer():
> |     query = flow.Threaded(flow.QueryIterator(dbpool, sql))
> |     yield query
> |     for row in query:
> |         print "Processed result : ", row
> |
> | from twisted.internet import reactor
> | def finish(result):
> |     print "Deferred Complete : ", result
> | f = flow.Deferred(consumer())
> | f.addBoth(finish)
> | reactor.callLater(1,reactor.stop)
> | reactor.run()
> |
> | # prints
> | # Processed result :  ('one',)
> | # Processed result :  ('two',)
> | # Processed result :  ('three',)
> | # Deferred Complete:  []
> |
> | ===========================
> |
> | > python flow-query.py
> | Deferred Complete :  [Failure instance: Traceback: exceptions.AttributeError, 'module' object has no attribute 'Threaded'
> | /opt/python/lib/python2.2/site-packages/twisted/flow/wrap.py:100:_yield
> | flow-query.py:18:consumer
> | ]
> |
> | Is there something I need to do? Has the API changed?
> |
> | Regards!
> | Ed
> |
> |
> |
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