2 files changed, 15 insertions, 2 deletions
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index db894c8aa9..f388b75c05 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -139,6 +139,16 @@ module ActiveRecord
       end
     end
 
+    # Pluck all the ID's for the relation using the table's primary key
+    #
+    # Examples:
+    #
+    #   Person.ids # SELECT people.id FROM people
+    #   Person.joins(:companies).ids # SELECT people.id FROM PEOPLE INNER JOIN companies ON companies.person_id = people.id
+    def ids
+      pluck primary_key
+    end
+
     private
 
     def perform_calculation(operation, column_name, options = {})
diff --git a/activerecord/lib/active_record/relation/finder_methods.rb b/activerecord/lib/active_record/relation/finder_methods.rb
index 416b55f5c5..1ceb1949a4 100644
--- a/activerecord/lib/active_record/relation/finder_methods.rb
+++ b/activerecord/lib/active_record/relation/finder_methods.rb
@@ -217,8 +217,11 @@ module ActiveRecord
       if match.bang? && result.blank?
         raise RecordNotFound, "Couldn't find #{@klass.name} with #{conditions.to_a.collect {|p| p.join(' = ')}.join(', ')}"
       else
-        yield(result) if block_given?
-        result
+        if block_given? && result
+          yield(result)
+        else
+          result
+        end
       end
     end