Eager loading with 'includes' overrides 'select' in SQL query #2303

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kommen commented Jul 27, 2011

When creating a query with select and includes like

Post.select('author_id, COUNT(author_id) AS num_posts, authors.*').group('author_id').includes(:author)

the select part is ignored when querying the database.

However, if to_sql is called on the Relation, the query gets constructed directly.

to_sql output:

SELECT author_id, COUNT(author_id) AS num_posts, authors.* FROM "posts"  GROUP BY author_id

query sent to the db:

SELECT "posts"."id" AS t0_r0, "posts"."author_id" AS t0_r1, "posts"."title" AS t0_r2, "posts"."body" AS t0_r3, "posts"."type" AS t0_r4, "posts"."comments_count" AS t0_r5, "posts"."taggings_count" AS t0_r6, "posts"."taggings_with_delete_all_count" AS t0_r7, "posts"."taggings_with_destroy_count" AS t0_r8, "posts"."tags_count" AS t0_r9, "posts"."tags_with_destroy_count" AS t0_r10, "posts"."tags_with_nullify_count" AS t0_r11, "authors"."id" AS t1_r0, "authors"."name" AS t1_r1, "authors"."author_address_id" AS t1_r2, "authors"."author_address_extra_id" AS t1_r3, "authors"."organization_id" AS t1_r4, "authors"."owned_essay_id" AS t1_r5 FROM "posts" LEFT OUTER JOIN "authors" ON "authors"."id" = "posts"."author_id" GROUP BY author_id

See the attached patch for a complete testcase which currently fails.

dipth commented Jan 17, 2012


the8472 commented Feb 9, 2012

Wouldn'g using preload instead of includes suffice in most cases?


isaacsanders commented May 4, 2012

This seems similar to #6132.


steveklabnik commented May 14, 2012

As a note, this no longer merges cleanly, so a rebase will be needed.


joevandyk commented Sep 8, 2012

Man, I'd love to see this fixed. So confusing to have #to_sql output something, but the query that runs is completely different.

nijikon commented Sep 10, 2012

Had a similar problem lately, wanted to run something like this:

select(s).joins(:rule, :campaign => :customer).joins(j).includes(:rule, :campaign, :customer).where(w.join(' AND ')).having(h.join(' AND ')).order('rule_resource.priority ASC').all


You need to replace

relation = except(:includes, :eager_load, :preload, :select).select(join_dependency.columns)


relation = except(:includes, :eager_load, :preload).select(join_dependency.columns)

Can anybody point out why there is a select there in the first place?
If it's there for a reason then having will never work in my case.


steveklabnik commented Nov 17, 2012

@kommen I mentioned 6 months ago that this needed rebased, are you still interested in following-up with this pull request?


kommen commented Nov 18, 2012

@steveklabnik Thanks for the reminder. I've rebased the commit onto the 3-1-stable branch. If you want me to open another pull request for 3-2-stable or master, let me know.


steveklabnik commented Nov 18, 2012

Oh! yes, 3-1-stable isn't getting any non-security fixes these days. The way we prefer it to is to open a pull against master, and then fixes get backported as necessary. So can you please re-submit against master? Thanks!

@kommen kommen added a commit to kommen/rails that referenced this pull request Nov 18, 2012

@kommen kommen Add test to ensure preloading works as expected with "select" and "in…

This didn't work in rails 3.1. See #2303 for more information and original pull request.

kommen commented Nov 18, 2012

@steveklabnik Turns out, this is fixed in 3.2 and also master. I've rebased onto master anyway, just in case: #8258

jyr commented Mar 1, 2013

This was added in 3.2.12? I fail to override the select

jyr commented Mar 1, 2013

I have same problem, @the8472 can you show me a example using preload?

I'm use

Property.group("bla").where("bla").select("DISTINCT ON(table.created_at) table.id, *").includes(bla)

the8472 commented Mar 2, 2013

Property.group("bla").where("bla").select("DISTINCT ON(table.created_at) table.id, *").joins(:bla).preload(:bla)

I have the same issue in 3.2.12.

Dish.select("dishes.*, ordered_dishes.id as dish_ordered"). includes(:ordered_dishes, :ordered_dishes => :user_menu). where("dishes.menu_section_id in (?) AND (user_menus.user_id = ? OR user_menus.user_id IS NULL)", menu_section_ids, user_id).


SELECT "dishes"."id" AS t0_r0, "dishes"."title" AS t0_r1, "dishes"."created_at" AS t0_r2, "dishes"."updated_at" AS t0_r3, "dishes"."menu_section_id" AS t0_r4, "ordered_dishes"."id" AS t1_r0, "ordered_dishes"."user_menu_id" AS t1_r1, "ordered_dishes"."dish_id" AS t1_r2, "ordered_dishes"."created_at" AS t1_r3, "ordered_dishes"."updated_at" AS t1_r4, "user_menus"."id" AS t2_r0, "user_menus"."weekly_menu_id" AS t2_r1, "user_menus"."user_id" AS t2_r2, "user_menus"."created_at" AS t2_r3, "user_menus"."updated_at" AS t2_r4, "user_menus"."ordered" AS t2_r5 FROM "dishes" LEFT OUTER JOIN "ordered_dishes" ON "ordered_dishes"."dish_id" = "dishes"."id" LEFT OUTER JOIN "user_menus" ON "user_menus"."id" = "ordered_dishes"."user_menu_id" WHERE (dishes.menu_section_id in (16,16,16) AND (user_menus.user_id = 2 OR user_menus.user_id IS NULL))

gamov commented Dec 9, 2015

Yes, select is still overridden by includes in 3.2.22

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