Add ActiveRecord::Result#first

When you only need the first element of a result set, you shouldn't need to
instantiate all of hash_rows.

2 files changed, 10 insertions, 0 deletions

diff --git a/activerecord/lib/active_record/result.rb b/activerecord/lib/active_record/result.rb
index 8e6cd6c82f..f45f664efe 100644
--- a/activerecord/lib/active_record/result.rb
+++ b/activerecord/lib/active_record/result.rb
@@ -75,6 +75,11 @@ module ActiveRecord
       hash_rows[idx]
     end
 
+    def first
+      return nil if @rows.empty?
+      Hash[@columns.zip(@rows.first)]
+    end
+
     def last
       hash_rows.last
     end
diff --git a/activerecord/test/cases/result_test.rb b/activerecord/test/cases/result_test.rb
index dec01dfa76..565593c500 100644
--- a/activerecord/test/cases/result_test.rb
+++ b/activerecord/test/cases/result_test.rb
@@ -22,6 +22,11 @@ module ActiveRecord
       ], result.to_hash
     end
 
+    test "first returns first row as a hash" do
+      assert_equal(
+        {'col_1' => 'row 1 col 1', 'col_2' => 'row 1 col 2'}, result.first)
+    end
+
     test "each with block returns row hashes" do
       result.each do |row|
         assert_equal ['col_1', 'col_2'], row.keys