Remove unnecessary `length` method for collection proxy

`length` is delegated to `records` (`load_target`) by
`ActiveRecord::Delegation`.

https://github.com/rails/rails/blob/v5.0.0/activerecord/lib/active_record/relation/delegation.rb#L38

2 files changed, 6 insertions, 12 deletions

diff --git a/activerecord/lib/active_record/associations/collection_association.rb b/activerecord/lib/active_record/associations/collection_association.rb
index e17ca81867..a02ec032a7 100644
--- a/activerecord/lib/active_record/associations/collection_association.rb
+++ b/activerecord/lib/active_record/associations/collection_association.rb
@@ -270,15 +270,6 @@ module ActiveRecord
         end
       end
 
-      # Returns the size of the collection calling +size+ on the target.
-      #
-      # If the collection has been already loaded +length+ and +size+ are
-      # equivalent. If not and you are going to need the records anyway this
-      # method will take one less query. Otherwise +size+ is more efficient.
-      def length
-        load_target.size
-      end
-
       # Returns true if the collection is empty.
       #
       # If the collection has been loaded
diff --git a/activerecord/lib/active_record/associations/collection_proxy.rb b/activerecord/lib/active_record/associations/collection_proxy.rb
index 926defbb47..ffdd1c04a3 100644
--- a/activerecord/lib/active_record/associations/collection_proxy.rb
+++ b/activerecord/lib/active_record/associations/collection_proxy.rb
@@ -802,6 +802,12 @@ module ActiveRecord
         @association.size
       end
 
+      ##
+      # :method: length
+      #
+      # :call-seq:
+      #   length()
+      #
       # Returns the size of the collection calling +size+ on the target.
       # If the collection has been already loaded, +length+ and +size+ are
       # equivalent. If not and you are going to need the records anyway this
@@ -822,9 +828,6 @@ module ActiveRecord
       #   #       #<Pet id: 2, name: "Spook", person_id: 1>,
       #   #       #<Pet id: 3, name: "Choo-Choo", person_id: 1>
       #   #    ]
-      def length
-        @association.length
-      end
 
       # Returns +true+ if the collection is empty. If the collection has been
       # loaded it is equivalent