explicitly including child associations that are also included in the parent association definition should not result in double records in the collection/double loads (#1110)

Signed-off-by: Michael Koziarski <michael@koziarski.com>
[#1110 state:committed]

2 files changed, 8 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/association_preload.rb b/activerecord/lib/active_record/association_preload.rb
index 99e3973830..6e194ab9b4 100644
--- a/activerecord/lib/active_record/association_preload.rb
+++ b/activerecord/lib/active_record/association_preload.rb
@@ -193,6 +193,7 @@ module ActiveRecord
       end
 
       def preload_has_one_association(records, reflection, preload_options={})
+        return if records.first.send("loaded_#{reflection.name}?")
         id_to_record_map, ids = construct_id_map(records)        
         options = reflection.options
         records.each {|record| record.send("set_#{reflection.name}_target", nil)}
@@ -214,6 +215,7 @@ module ActiveRecord
       end
 
       def preload_has_many_association(records, reflection, preload_options={})
+        return if records.first.send(reflection.name).loaded?
         options = reflection.options
 
         primary_key_name = reflection.through_reflection_primary_key_name
@@ -271,6 +273,7 @@ module ActiveRecord
       end
 
       def preload_belongs_to_association(records, reflection, preload_options={})
+        return if records.first.send("loaded_#{reflection.name}?")
         options = reflection.options
         primary_key_name = reflection.primary_key_name
 
diff --git a/activerecord/lib/active_record/associations.rb b/activerecord/lib/active_record/associations.rb
index d1a0b2f96a..7c0d0cb689 100755
--- a/activerecord/lib/active_record/associations.rb
+++ b/activerecord/lib/active_record/associations.rb
@@ -1248,6 +1248,11 @@ module ActiveRecord
             association.target.nil? ? nil : association
           end
 
+          define_method("loaded_#{reflection.name}?") do
+            association = instance_variable_get(ivar) if instance_variable_defined?(ivar)
+            association && association.loaded?
+          end
+
           define_method("#{reflection.name}=") do |new_value|
             association = instance_variable_get(ivar) if instance_variable_defined?(ivar)