from Massimo, in another reply today
(https://groups.google.com/forum/#!topic/web2py/RqSBO2dZU4E) :
query &= db.flatpage.f==request.function
is the same as
query = query & (db.flatpage.f==request.function)
Build a query from another query
On Saturday, March 28, 2015 at 11:14:44 AM UTC-5, gb wrote:
>
> What is the DAL Code to generate a query like this:
> SELECT * FROM product WHERE product.id=1 OR product.id=2 OR product.id=3
> OR product.id product.id=4 OR product.id=5;
> or even:
> SELECT * FROM product WHERE (product.id=1) OR (product.id=2) OR (
> product.id=3) OR (product.id=4) OR (product.id=5);
>
> I've tried both the DAL code approaches below and I always end up with
> crazy parentheses nesting which will eventually crash the DB driver e.g. in
> sqlite: <class 'sqlite3.OperationalError'> parser stack overflow
>
> Is there another way to use the DAL, or is my only option to write the
> SQL manually?
>
> db.define_table("product")
>
> selected_ids = [1,2,3,4,5]
> query = []
> for pid in selected_ids:
> query.append(db.product.id == pid)
>
> query = reduce(lambda a,b:a|b,query)
> #Ouputs this : (((((product.id = 1) OR (product.id = 2)) OR (
> product.id = 3)) OR (product.id = 4)) OR (product.id = 5))
>
>
>
> selected_ids = [1,2,3,4,5]
> query = []
> for pid in selected_ids:
> query |= db.product.id == pid
>
> #I get a bonus parenthesis with this method ((((((product.id = 1) OR
> ) OR (product.id = 2)) OR (product.id = 3)) OR (product.id = 4)) OR (
> product.id = 5))
>
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