Add reselect method

2 files changed, 19 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/relation/query_methods.rb b/activerecord/lib/active_record/relation/query_methods.rb
index 52405f21a1..74103d6cdd 100644
--- a/activerecord/lib/active_record/relation/query_methods.rb
+++ b/activerecord/lib/active_record/relation/query_methods.rb
@@ -240,6 +240,20 @@ module ActiveRecord
       self
     end
 
+    # Allows you to change a previously set select statement.
+    #
+    #   Post.select(:title, :body)
+    #   # SELECT `posts.title`, `posts.body` FROM `posts`
+    #
+    #   Post.select(:title, :body).reselect(:created_at)
+    #   # SELECT `posts.created_at` FROM `posts`
+    #
+    # This is short-hand for <tt>unscope(:select).select(fields)</tt>.
+    # Note that we're unscoping the entire select statement.
+    def reselect(*fields)
+      unscope(:select).select(*fields)
+    end
+
     # Allows to specify a group attribute:
     #
     #   User.group(:name)
diff --git a/activerecord/test/cases/relation/select_test.rb b/activerecord/test/cases/relation/select_test.rb
index dec8a6925d..32e8f473ff 100644
--- a/activerecord/test/cases/relation/select_test.rb
+++ b/activerecord/test/cases/relation/select_test.rb
@@ -11,5 +11,10 @@ module ActiveRecord
       expected = Post.select(:title).to_sql
       assert_equal expected, Post.select(nil).select(:title).to_sql
     end
+
+    def test_reselect
+      expected = Post.select(:title).to_sql
+      assert_equal expected, Post.select(:title, :body).reselect(:title).to_sql
+    end
   end
 end