From 85fe5edcec77f96923ed4f4e8b63a247ebe6b055 Mon Sep 17 00:00:00 2001
From: Aaron Patterson <aaron.patterson@gmail.com>
Date: Tue, 16 Jul 2013 13:41:24 -0700
Subject: decouple the manager class from building join constraints

---
 .../associations/join_dependency/join_association.rb         | 12 ++++++------
 activerecord/lib/active_record/relation/query_methods.rb     |  9 +++++----
 2 files changed, 11 insertions(+), 10 deletions(-)

diff --git a/activerecord/lib/active_record/associations/join_dependency/join_association.rb b/activerecord/lib/active_record/associations/join_dependency/join_association.rb
index ee1fcc17d8..3205cd41a2 100644
--- a/activerecord/lib/active_record/associations/join_dependency/join_association.rb
+++ b/activerecord/lib/active_record/associations/join_dependency/join_association.rb
@@ -64,7 +64,8 @@ module ActiveRecord
           end
         end
 
-        def join_to(manager)
+        def join_constraints
+          joins         = []
           tables        = @tables.dup
 
           foreign_table = parent_table
@@ -84,11 +85,10 @@ module ActiveRecord
               foreign_key = reflection.foreign_key
             when :has_and_belongs_to_many
               # Join the join table first...
-              manager.from(join(
+              joins << join(
                 table,
                 table[reflection.foreign_key].
-                  eq(foreign_table[reflection.active_record_primary_key])
-              ))
+                  eq(foreign_table[reflection.active_record_primary_key]))
 
               foreign_table, table = table, tables.shift
 
@@ -125,13 +125,13 @@ module ActiveRecord
               constraint = constraint.and rel.arel.constraints
             end
 
-            manager.from(join(table, constraint))
+            joins << join(table, constraint)
 
             # The current table in this iteration becomes the foreign table in the next
             foreign_table, foreign_klass = table, klass
           end
 
-          manager
+          joins
         end
 
         #  Builds equality condition.
diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index 612c7d17a3..fb585ab8ab 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -948,10 +948,11 @@ module ActiveRecord
 
       join_dependency.graft(*stashed_association_joins)
 
-      # FIXME: refactor this to build an AST
-      join_dependency.join_associations.each do |association|
-        association.join_to(manager)
-      end
+      joins = join_dependency.join_associations.map { |association|
+        association.join_constraints
+      }.flatten
+
+      joins.each { |join| manager.from join }
 
       manager.join_sources.concat join_list
 
-- 
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