Extract `construct_relation_for_exists` in `FinderMethods`

To ease to customize a relation for `exists?`.

1 files changed, 15 insertions, 12 deletions

diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index 5d24f5f5ca..14c2ddd85b 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -312,16 +312,7 @@ module ActiveRecord
       relation = apply_join_dependency(self, construct_join_dependency(eager_loading: false))
       return false if ActiveRecord::NullRelation === relation
 
-      relation = relation.except(:select, :distinct).select(ONE_AS_ONE).limit(1)
-
-      case conditions
-      when Array, Hash
-        relation = relation.where(conditions)
-      else
-        unless conditions == :none
-          relation = relation.where(primary_key => conditions)
-        end
-      end
+      relation = construct_relation_for_exists(relation, conditions)
 
       connection.select_value(relation, "#{name} Exists", relation.bound_attributes) ? true : false
     rescue ::RangeError
@@ -391,6 +382,19 @@ module ActiveRecord
         end
       end
 
+      def construct_relation_for_exists(relation, conditions)
+        relation = relation.except(:select, :distinct)._select!(ONE_AS_ONE).limit!(1)
+
+        case conditions
+        when Array, Hash
+          relation.where!(conditions)
+        else
+          relation.where!(primary_key => conditions) unless conditions == :none
+        end
+
+        relation
+      end
+
       def construct_join_dependency(joins = [], eager_loading: true)
         including = eager_load_values + includes_values
         ActiveRecord::Associations::JoinDependency.new(@klass, including, joins, eager_loading: eager_loading)
@@ -401,8 +405,7 @@ module ActiveRecord
       end
 
       def apply_join_dependency(relation, join_dependency)
-        relation = relation.except(:includes, :eager_load, :preload)
-        relation = relation.joins join_dependency
+        relation = relation.except(:includes, :eager_load, :preload).joins!(join_dependency)
 
         if using_limitable_reflections?(join_dependency.reflections)
           relation