1 files changed, 39 insertions, 34 deletions
diff --git a/activerecord/lib/active_record/result.rb b/activerecord/lib/active_record/result.rb
index 500c478e65..9ed70a9c2b 100644
--- a/activerecord/lib/active_record/result.rb
+++ b/activerecord/lib/active_record/result.rb
@@ -1,7 +1,8 @@
 module ActiveRecord
   ###
-  # This class encapsulates a Result returned from calling +exec_query+ on any
-  # database connection adapter. For example:
+  # This class encapsulates a result returned from calling
+  # {#exec_query}[rdoc-ref:ConnectionAdapters::DatabaseStatements#exec_query]
+  # on any database connection adapter. For example:
   #
   #   result = ActiveRecord::Base.connection.exec_query('SELECT id, title, body FROM posts')
   #   result # => #<ActiveRecord::Result:0xdeadbeef>
@@ -31,8 +32,6 @@ module ActiveRecord
   class Result
     include Enumerable
 
-    IDENTITY_TYPE = Type::Value.new # :nodoc:
-
     attr_reader :columns, :rows, :column_types
 
     def initialize(columns, rows, column_types = {})
@@ -74,8 +73,14 @@ module ActiveRecord
       hash_rows[idx]
     end
 
+    def first
+      return nil if @rows.empty?
+      Hash[@columns.zip(@rows.first)]
+    end
+
     def last
-      hash_rows.last
+      return nil if @rows.empty?
+      Hash[@columns.zip(@rows.last)]
     end
 
     def cast_values(type_overrides = {}) # :nodoc:
@@ -96,36 +101,36 @@ module ActiveRecord
 
     private
 
-    def column_type(name, type_overrides = {})
-      type_overrides.fetch(name) do
-        column_types.fetch(name, IDENTITY_TYPE)
+      def column_type(name, type_overrides = {})
+        type_overrides.fetch(name) do
+          column_types.fetch(name, Type.default_value)
+        end
       end
-    end
 
-    def hash_rows
-      @hash_rows ||=
-        begin
-          # We freeze the strings to prevent them getting duped when
-          # used as keys in ActiveRecord::Base's @attributes hash
-          columns = @columns.map { |c| c.dup.freeze }
-          @rows.map { |row|
-            # In the past we used Hash[columns.zip(row)]
-            #  though elegant, the verbose way is much more efficient
-            #  both time and memory wise cause it avoids a big array allocation
-            #  this method is called a lot and needs to be micro optimised
-            hash = {}
-
-            index = 0
-            length = columns.length
-
-            while index < length
-              hash[columns[index]] = row[index]
-              index += 1
-            end
-
-            hash
-          }
-        end
-    end
+      def hash_rows
+        @hash_rows ||=
+          begin
+            # We freeze the strings to prevent them getting duped when
+            # used as keys in ActiveRecord::Base's @attributes hash
+            columns = @columns.map { |c| c.dup.freeze }
+            @rows.map { |row|
+              # In the past we used Hash[columns.zip(row)]
+              #  though elegant, the verbose way is much more efficient
+              #  both time and memory wise cause it avoids a big array allocation
+              #  this method is called a lot and needs to be micro optimised
+              hash = {}
+
+              index = 0
+              length = columns.length
+
+              while index < length
+                hash[columns[index]] = row[index]
+                index += 1
+              end
+
+              hash
+            }
+          end
+      end
   end
 end