帖子内容可以为空

app/models/memo.rb

@@ -4,7 +4,7 @@ class Memo < ActiveRecord::Base
 	belongs_to :author, :class_name => "User", :foreign_key => 'author_id' 
 
 	validates_presence_of :author_id, :forum_id, :subject
-	validates :content, presence: true
+	#validates :content, presence: true
 	validates_length_of :subject, maximum: 50
 	#validates_length_of :content, maximum: 3072
 	validate :cannot_reply_to_locked_topic, :on => :create