I would replace
retVal = []
for entity in db(db.table2.id > 0).select():
retVal += entity.table1.name
with
table1_map = db(db.table2 <http://db.table2.id/>).select().as_dict()
retVal = [table1_map[entity.table1].name <http://entity.table1.name/> for
entity in db(db.table2 <http://db.table2.id/>).select()]
It will loads all records from table1 in ram but your code does it too. Two
queries instead of many.
select().as_dict() creates a dict where the key is the id and the value is
the record.
On Tuesday, 4 June 2013 04:25:06 UTC-5, guruyaya wrote:
>
> Lets examine this code for a sec:
> db.define_table('table1',Field('name'))
> db.define_table('table2',Field('table1', db.table1), Field('name2'))
>
> Now, if I need a list of all table2 entries, but not the table1 entries,
> I'll do something like this:
>
> retVal = []
> for entity in db(db.table2.id > 0).select():
> retVal += entity.name2
>
> BUT
> As you well know, web2py acctuall did ask for table1 info, just in case
> I'll do this:
>
> retVal = []
> for entity in db(db.table2.id > 0).select():
> retVal += entity.table1.name
>
> On a normal hosting, it doesn't matter that much, but on GAE, it does an
> extra query to the datastore, and that's just a waste.
> Is there a way to avoid that?
>
> Thanks in advance
> Yair
>
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