eager loading of associations not working in rails 3?

Hey Jason,

Can you provide a failing test or something more specific, because i tried this on master:

Post.joins(:comments).includes(:comments).all

and you get this 2 queries:

SELECT "posts". FROM "posts" INNER JOIN "comments" ON "comments"."post_id" = "posts"."id"
SELECT "comments". FROM "comments" WHERE ("comments".post_id IN (1,2,4,5,7)).

Which shows eager loading is working properly.

I see...

I had thought that includes(:bar) would generate an OUTER JOIN clause in the original SQL, rather than generating a second SELECT with an IN clause, i.e.

Post.includes(:comments).all

would generate (for has_many)

SELECT "posts".*, "comments".* FROM "posts" LEFT OUTER JOIN "comments" ON "comments"."post_id" = "posts"."id"

instead of

SELECT "posts".* FROM "posts"
SELECT "comments". FROM "comments" WHERE ("comments".post_id IN (...))

My problem is that the 2-query situation doesn't allow for iterating through the results without pre-fetching everything. Doesn't that bust Arel's closure objective?

Hi Emilio-

I think your example should have comments.title in the conditions instead of post.title.

Is it possible to express your example using Arel-style syntax? Something like

Post.includes(:comment).where(comment[:title].eq("Welcome..."))

I'm not sure how to refer to comment here, the example code I could find refers to an Arel::Table method but this seems to be private.

Thanks,
-Jason

Jason,

You could try something like this:

Post.includes(:comments).where(Comment.arel_table[:title].eq("Welcome ..."))

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