On Apr 24, 6:06 am, Juan Pablo Avello <[email protected]> wrote:
> El martes, 24 de abril de 2012 03:56:21 UTC+2, Rafael C. de Almeida
> escribió:
> > Hello
>
> > I have two tables: Lawyer and Phone. Phone is separated into area code
> > and number. A lawyer has many phones. I want to produce a query which
> > searches for lawyers who have a phone matching a phone from a list of
> > phones.
> > select * from phones where (area_code, number) in (('555',
> > '1234564'), ('533', '12345678'))
>
> > How to translate that to ActiveRecord?
>
> Your best option is probably:
>
> Lawyer.includes(:phones).where( :phones => {:area_code =>
> phone[:area_code], :number =>
> phone[:number]}) }
>
> Then you may iterate through phones at your will.
>
> Using .includes() preloads related models, phones in this case, and
> subsequent queries do not actually query the db but the data structure
> stored in memory (you can easily check this in a console; with .includes()
> no 'select *...' will appear on the logs when accessing a lawyer's phones)
That doesn't seem to work. First I tried the approach with joins:
1.9.3p194 :071 > lawyers = []
1.9.3p194 :071 > phones = [{area_code:'31', number:'32210412'},
{area_code:'32', number:'32210412'}]
1.9.3p194 :071 > phones.each { |phone| lawyers +=
Lawyer.joins(:phones).where(phones:phone) }
Lawyer Load (1.0ms) SELECT "lawyers".* FROM "lawyers" INNER JOIN
"phones" ON "phones"."lawyer_id" = "lawyers"."id" WHERE
"phones"."area_code" = '31' AND "phones"."number" = '32210412'
Lawyer Load (0.4ms) SELECT "lawyers".* FROM "lawyers" INNER JOIN
"phones" ON "phones"."lawyer_id" = "lawyers"."id" WHERE
"phones"."area_code" = '32' AND "phones"."number" = '32210412'
Then I tried it with includes:
phones.each { |phone| lawyers +=
Lawyer.includes(:phones).where(phones:phone) }
includes' version was more verbose, but made two SQL queries as well.
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