Wow Michael,
this syntax is very powerfull!
Two questions before I can make mistakes:
1 - the number 100 is recovered by something like len(value_list)-1, where
value_list contains alls the values I want to search?
2 - id_rec for id_rec: I must to pass this in the same way you wrote?
Thanks a lot and best regards
Luca
On Sun, Sep 29, 2013 at 5:57 PM, Michael Bayer <mike...@zzzcomputing.com>wrote:
>
> On Sep 29, 2013, at 10:56 AM, pyArchInit ArcheoImagineers <
> pyarchi...@gmail.com> wrote:
>
> Hi to all.
> I try to use the code in this way (query LIKE with OR operator)
>
> res = session.query(MAPPER).filter(or_(MAPPER.field.contains('Value1'),
> MAPPER.field.contains('Value2'), MAPPER.field.contains('Value3'),MAPPER
> .field.contains('Value4')))
>
> With a small dataset, I found the records I want, but with a larger
> dataset sqlalchemy return me an error:
>
> more than 255 arguments.
>
> To bypass this problem in the past I used the operator in_ in this way:
>
> id_list = [1, 2, 3]
>
> session.query(CLASS).filter(CLASS.field.in_(id_list)).all()
>
> I've guessed that was possible to make something like this:
>
> value_to_find = [CLASS.field.contains('value1'),
> CLASS.field.contains('value2')]
>
> session.query(CLASS).filter(CLASS.field.in_(value_to_find)).all()
>
> This script runs without error, but didn't return me any result.
>
> Because is a OR type query, it's a good idea make single research for each
> value and storing the id of every record in a list?
>
> Smothing like this:
>
> res_list = []
> for value in value_list:
> res = session.query(MAPPER).filter(MAPPER.field.contains(value))
> for r in res:
> res_list.append(res.id_record)
>
>
> I'd batch them (also if you only need "id_record", query for that
> specifically):
>
> res_list = []
> while value_list:
> chunk = value_list[0:100]
> value_list = value_list[100:]
> res_list.extend(id_rec for id_rec, in
> session.query(M.id_record).filter(or_(*[M.field.contains(v) for v in
> chunk])))
>
>
>
>
>
>
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