1 files changed, 32 insertions, 1 deletions
diff --git a/activerecord/lib/active_record/relation/calculations.rb b/activerecord/lib/active_record/relation/calculations.rb
index af86771d2d..63365e501b 100644
--- a/activerecord/lib/active_record/relation/calculations.rb
+++ b/activerecord/lib/active_record/relation/calculations.rb
@@ -166,6 +166,37 @@ module ActiveRecord
       0
     end
 
+    # This method is designed to perform select by a single column as direct SQL query
+    # Returns <tt>Array</tt> with values of the specified column name
+    # The values has same data type as column.
+    #
+    # Examples:
+    #
+    #   Person.pluck(:id) # SELECT people.id FROM people
+    #   Person.uniq.pluck(:role) # SELECT DISTINCT role FROM people
+    #   Person.where(:confirmed => true).limit(5).pluck(:id)
+    #
+    def pluck(column_name)
+      key = column_name.to_s.split('.', 2).last
+
+      if column_name.is_a?(Symbol) && column_names.include?(column_name.to_s)
+        column_name = "#{table_name}.#{column_name}"
+      end
+
+      result = klass.connection.select_all(select(column_name).arel)
+      types  = result.column_types.merge klass.column_types
+      column = types[key]
+
+      result.map do |attributes|
+        value = klass.initialize_attributes(attributes)[key]
+        if column
+          column.type_cast value
+        else
+          value
+        end
+      end
+    end
+
     private
 
     def perform_calculation(operation, column_name, options = {})
@@ -317,7 +348,7 @@ module ActiveRecord
     def select_for_count
       if @select_values.present?
         select = @select_values.join(", ")
-        select if select !~ /(,|\*)/
+        select if select !~ /[,*]/
       end
     end