Merge pull request #14573 from habermann24/has_many_through_fix

Properly handle scoping with has_many :through. Fixes #14537.

Conflicts:
	activerecord/CHANGELOG.md
	activerecord/test/cases/associations/has_many_through_associations_test.rb

activerecord/CHANGELOG.md

+*   Fixed unexpected behavior for `has_many :through` associations going through a scoped `has_many`.
+
+    If a `has_many` association is adjusted using a scope, and another `has_many :through`
+    uses this association, then the scope adjustment is unexpectedly neglected.
+
+    Fixes #14537.
+
+    *Jan Habermann*
+
 *   `@destroyed` should always be set to `false` when an object is duped.
 
     *Kuldeep Aggarwal*

activerecord/lib/active_record/associations/through_association.rb

@@ -14,9 +14,11 @@ module ThroughAssociation #:nodoc:
         def target_scope
           scope = super
           chain.drop(1).each do |reflection|
+            relation = reflection.klass.all
+            relation.merge!(reflection.scope) if reflection.scope
+
             scope.merge!(
-              reflection.klass.all.
-                except(:select, :create_with, :includes, :preload, :joins, :eager_load)
+              relation.except(:select, :create_with, :includes, :preload, :joins, :eager_load)
             )
           end
           scope

activerecord/test/cases/associations/has_many_through_associations_test.rb

@@ -1116,5 +1116,16 @@ def test_has_many_through_obeys_order_on_through_association
 
     club.reload
     assert_equal [member], club.favourites
+
+  def test_has_many_through_unscope_default_scope
+    post = Post.create!(:title => 'Beaches', :body => "I like beaches!")
+    Reader.create! :person => people(:david), :post => post
+    LazyReader.create! :person => people(:susan), :post => post
+
+    assert_equal 2, post.people.to_a.size
+    assert_equal 1, post.lazy_people.to_a.size
+
+    assert_equal 2, post.lazy_readers_unscope_skimmers.to_a.size
+    assert_equal 2, post.lazy_people_unscope_skimmers.to_a.size
   end
 end

activerecord/test/models/post.rb

@@ -145,6 +145,10 @@ def add_joins_and_select
   has_many :lazy_readers
   has_many :lazy_readers_skimmers_or_not, -> { where(skimmer: [ true, false ]) }, :class_name => 'LazyReader'
 
+  has_many :lazy_people, :through => :lazy_readers, :source => :person
+  has_many :lazy_readers_unscope_skimmers, -> { skimmers_or_not }, :class_name => 'LazyReader'
+  has_many :lazy_people_unscope_skimmers, :through => :lazy_readers_unscope_skimmers, :source => :person
+
   def self.top(limit)
     ranked_by_comments.limit_by(limit)
   end

activerecord/test/models/reader.rb

@@ -16,6 +16,8 @@ class LazyReader < ActiveRecord::Base
   self.table_name = "readers"
   default_scope -> { where(skimmer: true) }
 
+  scope :skimmers_or_not, -> { unscope(:where => :skimmer) }
+
   belongs_to :post
   belongs_to :person
 end