Merge pull request #512 from CanCanCommunity/kaspernj-optimised-queri…

…es-with-left-joins

Kaspernj optimised queries with left joins

CHANGELOG.rdoc

@@ -2,6 +2,7 @@ Unreleased
 
 * Drop support for actions without a subject (andrew-aladev)
 * Allow to add attribute-level rules (phaedryx)
+* Removed eager loading of associations for ActiveRecord 5 (kaspernj)
 
 2.2.0 (Apr 13th, 2018)
 

lib/cancan/model_adapters/active_record_5_adapter.rb

@@ -22,13 +22,9 @@ def self.matches_condition?(subject, name, value)
 
       private
 
-      # As of rails 4, `includes()` no longer causes active record to
-      # look inside the where clause to decide to outer join tables
-      # you're using in the where. Instead, `references()` is required
-      # in addition to `includes()` to force the outer join.
       def build_relation(*where_conditions)
         relation = @model_class.where(*where_conditions)
-        relation = relation.includes(joins).references(joins) if joins.present?
+        relation = relation.left_joins(joins).distinct if joins.present?
         relation
       end
 

spec/cancan/model_adapters/active_record_4_adapter_spec.rb

@@ -153,7 +153,6 @@ class Child < ActiveRecord::Base
           parent = Parent.create!
           Child.create!(parent: parent, created_at: 1.hours.ago)
           Child.create!(parent: parent, created_at: 2.hours.ago)
-
           expect(Parent.accessible_by(@ability)).to eq([parent])
         end
       end