add formData support

test-app/db/migrate/20160218212104_create_blogs.rb

@@ -3,6 +3,7 @@ class CreateBlogs < ActiveRecord::Migration
     create_table :blogs do |t|
       t.string :title
       t.text :content
+      t.string :thumbnail
 
       t.timestamps
     end

test-app/db/schema.rb

@@ -16,6 +16,7 @@ ActiveRecord::Schema.define(:version => 20160218212104) do
   create_table "blogs", :force => true do |t|
     t.string   "title"
     t.text     "content"
+    t.string   "thumbnail"
     t.datetime "created_at", :null => false
     t.datetime "updated_at", :null => false
   end