i use: ids = [...generate your list of ids...]
rows = db(db.board.id.belongs(ids[0:30]).select() for i in range(30,len(ids), 30): rows & db(db.board.id.belongs(ids[i:i+30]).select() so that gets me my "in" statement working with GAE's 30 items per in limit. On Wednesday, March 21, 2012 10:05:46 PM UTC-7, Udi Milo wrote: > > I went with: > > query = '' > for id in board_ids: > query += 'db(db.board.id==%d).select()|' %id > query = query[:-1] > boards = eval(query) > > I have no idea how to evaluate performance of that query though.... > if you have any other ideas (I cannot limit 30 right now without > rethinking other things), please share them. > > On Wednesday, March 21, 2012 11:52:33 PM UTC-4, Anthony wrote: >> >> I think that is outdated -- according to this ( >> https://groups.google.com/d/msg/web2py/vWqOET74qg4/92DLUFTUsN0J<https://groups.google.com/d/msg/web2py/vWqOET74qg4/92DLUFTUsN0J>), >> >> GAE does now support belongs but is limited to 30 items per query (so you >> have to break it up). Perhaps there is a better way, though. >> >> Anthony >> >> On Wednesday, March 21, 2012 9:26:44 PM UTC-4, Udi Milo wrote: >>> >>> It doesn't. >>> I found this: >>> """" >>> GAE does not support belongs and does not support OR. You have to do: >>> >>> rows = db(db.media_type.name=='paper').select()&db >>> (db.media_type.name=='cd').select() >>> >>> The & is done at the web2py level but since records are exclusive and >>> you are not sorting them, there is no major slowdown. >>> """"" >>> >>> Since I'm a python newbie, how would you go about building the loop that >>> creates a very long query? you need to do some kind of python eval tricks >>> here that I don't know. >>> I'm guessing its going to look like >>> >>> for id in board_ids: >>> query = query + new query(id) >>> >>> but how do you do it in python? >>> >>> On Wednesday, March 21, 2012 8:30:54 PM UTC-4, Anthony wrote: >>>> >>>> I didn't realize you were on GAE. I'm not quite sure how GAE handles >>>> this, so perhaps someone with more GAE experience can chime in. In an >>>> RDBMS, you should be able to do: >>>> >>>> board_ids = set([a.board for a in articles]) >>>> boards = db(db.boards.id.belongs(board_ids)).select() >>>> >>>> But not sure if that works on GAE. >>>> >>>> Anthony >>>> >>>> On Wednesday, March 21, 2012 7:30:58 PM UTC-4, Udi Milo wrote: >>>>> >>>>> Anthony, >>>>> >>>>> Thanks for answering so quickly. >>>>> I did mean board and not board_id >>>>> >>>>> My question is very basic. >>>>> I know that the article table has an Id column that is really the >>>>> board reference, but when I look at the result of the query and >>>>> unification >>>>> of: >>>>> board_ids = set(map(lambda a: a.board, articles)) >>>>> >>>>> I get a set of references, >>>>> how do I use that set in another query to get all the boards? >>>>> also, just to be sure, running this lambda expression does not hit the >>>>> db to fetch the boards, right? >>>>> >>>>> I can't use join b/c I'm running on GAE. >>>>> >>>>> >>>>> >>>>> On Wednesday, March 21, 2012 5:22:50 PM UTC-4, Anthony wrote: >>>>>> >>>>>> I have two db tables: >>>>>>> >>>>>>> board (name, created_on) >>>>>>> article(board, name, title) >>>>>>> >>>>>>> currently, in my html I do a naive loop {{for article in articles}} >>>>>>> {{=article.board.name}} {{pass}} >>>>>>> >>>>>>> I would like to change it and do something like: >>>>>>> articles = db.select.all....... >>>>>>> board_ids = set(map(lambda a: a.board_id, articles)) >>>>>>> >>>>>> >>>>>> Instead of a.board_id, do you mean a.board (I don't see a "board_id" >>>>>> field listed in your article table definition)? Also, is >>>>>> db.article.board a >>>>>> reference field to the db.board table? In that case, that means it is >>>>>> already storing the id of the referenced record in the db.board table >>>>>> (that's what reference fields store), so you don't need to retrieve it >>>>>> separately. >>>>>> >>>>>> Anyway, if you need the db.board.name value for all the records you >>>>>> are selecting from the db.article table, you should probably just do a >>>>>> join >>>>>> so you can get everything in a single query -- see >>>>>> http://web2py.com/books/default/chapter/29/6#Inner-joins<http://web2py.com/books/default/chapter/29/6#Inner-joins> >>>>>> . >>>>>> >>>>>> Anthony >>>>>> >>>>>>
