active record relations – who needs it?
- by M2_
Well, I`m confused about rails queries. For example:
Affiche belongs_to :place
Place has_many :affiches
We can do this now:
@affiches = Affiche.all( :joins => :place )
or
@affiches = Affiche.all( :include => :place )
and we will get a lot of extra SELECTs, if there are many affiches:
Place Load (0.2ms) SELECT "places".* FROM "places" WHERE "places"."id" = 3 LIMIT 1
Place Load (0.3ms) SELECT "places".* FROM "places" WHERE "places"."id" = 3 LIMIT 1
Place Load (0.8ms) SELECT "places".* FROM "places" WHERE "places"."id" = 444 LIMIT 1
Place Load (1.0ms) SELECT "places".* FROM "places" WHERE "places"."id" = 222 LIMIT 1
...and so on...
And (sic!) with :joins used every SELECT is doubled!
Technically we cloud just write like this:
@affiches = Affiche.all( )
and the result is totally the same! (Because we have relations declared). The wayout of keeping all data in one query is removing the relations and writing a big string with "LEFT OUTER JOIN", but still there is a problem of grouping data in multy-dimentional array and a problem of similar column names, such as id.
What is done wrong? Or what am I doing wrong?
UPDATE:
Well, i have that string Place Load (2.5ms) SELECT "places".* FROM "places" WHERE ("places"."id" IN (3,444,222,57,663,32,154,20)) and a list of selects one by one id. Strange, but I get these separate selects when I`m doing this in each scope:
<%= link_to a.place.name, **a.place**( :id => a.place.friendly_id ) %>
the marked a.place is the spot, that produces these extra queries.
