[Twisted-Python] Using different cursor types with psycopg+twisted.enterprise.adbapi?
phil at bubblehouse.org
Fri Apr 18 14:05:03 EDT 2008
On Apr 18, 2008, at 1:09 PM, Nathan wrote:
> In my non-twisted scripts, I usually use psycopg2 DictCursors so that
> my query results come back in dicts instead of lists.
> curs = db.cursor(cursor_factory = psycopg2.extras.DictCursor)
> Now I'd like to do the same thing in Twisted. Is there a way to ask
> t.e.adbapi to use that DictCursor cursor factory?
> Or maybe there's a way to globally configure psycopg2 so that it used
> psycopg2.extras.DictCursor by default...
I think I ran into this while trying to support multiple DB drivers.
The adbapi.ConnectionPool constructor automatically passes any
additional arguments or keyword params to the DB-API Connection object
I remember having problems setting a default cursor via Connection()
params, but I thought it was with the other PG driver, not psycopg2.
In fact, I almost seem to remember pgdb not even directly supporting
DictCursors at all, but I could easily be mistaken.
In any event, I ended up having the real drivers return a the row as
sequence (the normal behavior), and made a trivial ConnectionPool
subclass that contained the following:
def _runInteraction(self, interaction, *args, **kw):
conn = adbapi.Connection(self)
trans = adbapi.Transaction(self, conn)
result = interaction(trans, *args, **kw)
if(result and isinstance(result, (list, tuple))):
result = [dict(zip([c for c in
trans._cursor.description], item)) for item in result]
Hacky, I know, but it did the trick. This way if you have a driver
that does support DictCursors by passing params to the Connection
constructor, it will use that functionality instead.
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