On Wed, Jan 25, 2012 at 1:35 PM, Clem Rock <[email protected]> wrote:
> Peter - big thanks for your help. You were right - I meant to say
> "the layouts table can have many photos"
>
> Looks like this was the winner for me:
>
> @properties = Property.paginate(:page => params[:page], :per_page =>
> 20).includes(:photos).includes(:layouts).order("properties.modify_date,
> layouts.modify_date").all
>
TL;DR : remove the '.all' at the end
In my example, I terminated with '.all' so that you would get a simple Array
as the result.
Once you have settled on a certain formula for the @properties, it might be
better to not longer write the '.all' at the end of the chain. Without the
.all' ,
you will get an ActiveRecord::Relation on which you can continue to chain
conditions etc. The real query will then only be done in a later stage of
the
calculation when the description of the ActiveRecord::Relation is complete.
If you ever test this in rails console, it will seem that the query is
always done
immediately. That is because irb calls .inspect on the last result of the
line.
One trick to make this work in rails console is to add ; nil at the end:
1.9.3-p0 :030 > p1 = Parent.order("parents.name") ; nil
=> nil
1.9.3-p0 :031 > p2 = p1.where("NOT parents.name IS NULL") ; nil
=> nil
1.9.3-p0 :032 > p3 = p2.includes(:child) ; nil
=> nil
1.9.3-p0 :033 > p3.all
Parent Load (0.6ms) SELECT "parents".* FROM "parents" WHERE (NOT
parents.name IS NULL) ORDER BY parents.name
Child Load (0.4ms) SELECT "children".* FROM "children" WHERE
"children"."parent_id" IN (1, 2, 3)
=> [#<Parent id: 1, name: "dad", created_at: "2012-01-24 10:05:43",
updated_at: "2012-01-24 10:05:43">, #<Parent id: 2, name: "dad",
created_at: "2012-01-24 10:06:59", updated_at: "2012-01-24 10:06:59">,
#<Parent id: 3, name: "mom", created_at: "2012-01-24 10:07:42", updated_at:
"2012-01-24 10:07:42">]
1.9.3-p0 :034 > p4 = p3.order("children.created_at") ; nil
=> nil
1.9.3-p0 :035 > p4.all
SQL (0.7ms) SELECT "parents"."id" AS t0_r0, "parents"."name" AS t0_r1,
"parents"."created_at" AS t0_r2, "parents"."updated_at" AS t0_r3,
"children"."id" AS t1_r0, "children"."name" AS t1_r1,
"children"."parent_id" AS t1_r2, "children"."created_at" AS t1_r3,
"children"."updated_at" AS t1_r4 FROM "parents" LEFT OUTER JOIN "children"
ON "children"."parent_id" = "parents"."id" WHERE (NOT parents.name IS NULL)
ORDER BY parents.name, children.created_at
=> [#<Parent id: 1, name: "dad", created_at: "2012-01-24 10:05:43",
updated_at: "2012-01-24 10:05:43">, #<Parent id: 2, name: "dad",
created_at: "2012-01-24 10:06:59", updated_at: "2012-01-24 10:06:59">,
#<Parent id: 3, name: "mom", created_at: "2012-01-24 10:07:42", updated_at:
"2012-01-24 10:07:42">]
HTH,
Peter
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