My question
It seems like Rails 4 is ignoring nested unscoped blocks (whereas they were ok in Rails 3). I've been Googling like crazy and can't find anything indicating a change here. Any ideas how I can get this working in Rails 4?
What I'm doing
I'm using default_scope for multi-tenancy as shown in #388 Multitenancy with Scopes. Some admins will be admin of multiple tenants, and I want to show them aggregated data in a report. I'm doing this by using unscoped blocks. I'm also preloading associated objects because 1) It's more efficient and 2) I need to get all the associated objects in one place so I don't have to keep using unscoped blocks in my views. To preload the associated objects, I'm using nested unscoped blocks.
I had this working in my app on Rails 3.2.17, but now that I've upgraded to Rails 4.0.1.rc1, it no longer works.
A simple example to illustrate the difference
Below, I'll show what I'm getting in the Console. This example is much simpler than what I actually want to do, but I think it's the easiest way to show what's going on.
Loading development environment (Rails 3.2.17)
1.9.3-p374 :001 > s = nil
=> nil
1.9.3-p374 :002 > Submission.unscoped { Checklist.unscoped { s = Submission.preload(:checklist).find(3269) }}
Submission Load (27.8ms) SELECT "submissions".* FROM "submissions" WHERE "submissions"."id" = $1 LIMIT 1 [["id", 3269]]
Checklist Load (0.6ms) SELECT "checklists".* FROM "checklists" WHERE "checklists"."id" IN (17)
=> #<Submission id: 3269, user_id: nil, workday_id: 17, checklist_id: 17, note: nil, submitted: false, submitted_at: nil, created_at: "2014-03-12 01:06:03", updated_at: "2014-03-12 01:06:03", for_date: "2014-03-11", tenant_id: 2, position: 1, department_id: nil, status: "blank">
1.9.3-p374 :003 > s
=> #<Submission id: 3269, user_id: nil, workday_id: 17, checklist_id: 17, note: nil, submitted: false, submitted_at: nil, created_at: "2014-03-12 01:06:03", updated_at: "2014-03-12 01:06:03", for_date: "2014-03-11", tenant_id: 2, position: 1, department_id: nil, status: "blank">
1.9.3-p374 :004 > s.checklist
=> #<Checklist id: 17, name: "Open", description: "Chores Required To Open Store Front", creator_id: 2, created_at: "2013-09-23 21:55:23", updated_at: "2013-09-23 21:55:23", archived: false, archived_at: nil, ancestry: nil, tenant_id: 2>
So, I'm loading a submission and preloading its associated checklist. Then I can confirm that both the submission and its associated checklist are available.
If I switch to my Rails 4 environment (both working on the same database), here is what I see:
Loading development environment (Rails 4.1.0.rc1)
1.9.3-p374 :001 > s = nil
=> nil
1.9.3-p374 :002 > Submission.unscoped { Checklist.unscoped { s = Submission.preload(:checklist).find(3269) }}
Submission Load (0.4ms) SELECT "submissions".* FROM "submissions" WHERE "submissions"."id" = $1 LIMIT 1 [["id", 3269]]
Checklist Load (0.6ms) SELECT "checklists".* FROM "checklists" WHERE "checklists"."tenant_id" IS NULL AND "checklists"."id" IN (17)
=> #<Submission id: 3269, user_id: nil, workday_id: 17, checklist_id: 17, note: nil, submitted: false, submitted_at: nil, created_at: "2014-03-12 01:06:03", updated_at: "2014-03-12 01:06:03", for_date: "2014-03-11", tenant_id: 2, position: 1, department_id: nil, status: "blank">
1.9.3-p374 :003 > s
=> #<Submission id: 3269, user_id: nil, workday_id: 17, checklist_id: 17, note: nil, submitted: false, submitted_at: nil, created_at: "2014-03-12 01:06:03", updated_at: "2014-03-12 01:06:03", for_date: "2014-03-11", tenant_id: 2, position: 1, department_id: nil, status: "blank">
1.9.3-p374 :004 > s.checklist
=> nil
I'm running exactly the same code, but only the Submission is available - its associated checklist is nil.
FWIW, I can duplicate this in Rails 3.2.17 if I run this in the Console. NOTE: The difference here is I'm only using a Submission.unscoped {} block and not nesting the Checklist.unscoped {} block.
Loading development environment (Rails 3.2.17)
1.9.3-p374 :001 > s = nil
=> nil
1.9.3-p374 :002 > Submission.unscoped { s = Submission.preload(:checklist).find(3269) }
Submission Load (3.6ms) SELECT "submissions".* FROM "submissions" WHERE "submissions"."id" = $1 LIMIT 1 [["id", 3269]]
Checklist Load (0.4ms) SELECT "checklists".* FROM "checklists" WHERE "checklists"."tenant_id" IS NULL AND "checklists"."id" IN (17)
=> #<Submission id: 3269, user_id: nil, workday_id: 17, checklist_id: 17, note: nil, submitted: false, submitted_at: nil, created_at: "2014-03-12 01:06:03", updated_at: "2014-03-12 01:06:03", for_date: "2014-03-11", tenant_id: 2, position: 1, department_id: nil, status: "blank">
1.9.3-p374 :003 > s
=> #<Submission id: 3269, user_id: nil, workday_id: 17, checklist_id: 17, note: nil, submitted: false, submitted_at: nil, created_at: "2014-03-12 01:06:03", updated_at: "2014-03-12 01:06:03", for_date: "2014-03-11", tenant_id: 2, position: 1, department_id: nil, status: "blank">
1.9.3-p374 :004 > s.checklist
=> nil
UPDATE
I went digging into the Rails source and I can see that the "unscoped" method is the same in 3.2-stable as current master, BUT that method calls "relation.scoping" and that method is substantially different between the two branches. I'm not sure if there's been a bug introduced, or if the expected behavior has changed.
For reference:
def unscoped
block_given? ? relation.scoping { yield } : relation
end
relation.scoping
def scoping
previous, klass.current_scope = klass.current_scope, self
yield
ensure
klass.current_scope = previous
end
current_scope
def current_scope #:nodoc:
ScopeRegistry.value_for(:current_scope, base_class.to_s)
end
def unscoped #:nodoc:
block_given? ? relation.scoping { yield } : relation
end
relation.scoping
def scoping
@klass.with_scope(self, :overwrite) { yield }
end
Link to with_scope method...
def with_scope
# Pretty long and involved method
# See Line 60 in the linked doc
end
It looks like I've stumbled into a Rails 4 bug. As far as I can tell, using unscoped and eager loading together is currently not possible in Rails 4 as it seems that 'unscoped' essentially doesn't nest or chain.
Here's the issue on Github:
Using Includes and Unscoped #11036
What I ended up doing (for now) is to create unscoped associations (now available in Rails 4) where I needed them. Here's an example (from the gist I added to the Github issue):
class Submission < ActiveRecord::Base
default_scope { where(tenant_id: Tenant.current_id) }
belongs_to :checklist
###### This unscoped association is my workaround in Rails 4
###### You'll want comment out if testing in Rails 3
belongs_to :unscoped_checklist, -> { unscope(where: :tenant_id) }, foreign_key: :checklist_id, class_name: "Checklist"
belongs_to :tenant
end
So, I can just call submission.unscoped_checklist to get around the default_scope. Note, however, that this will not work in conjunction with eager loading. For example, this will not work:
Submission.unscoped.preload(:unscoped_checklist).where(id: 1)
The Submission will be returned, but subsequently calling submission.unscoped_checklist will return nil.
So I'm currently not able to eager load unscoped associations, but I have figured out how to get to the unscoped associations when I need them.