fix reply message api

app/controllers/messages_controller.rb

@@ -51,7 +51,8 @@ class MessagesController < ApplicationController
 
   def reply
     return normal_status(2, "回复内容不能为空") if params[:content].blank?
-    @reply = Message.create!(board: @message.board, root: @message.root, author: current_user, parent: @message,
+    @reply = Message.create!(board: @message.board, root_id: @message.root_id || @message.id,
+                             author: current_user, parent: @message,
                              message_detail_attributes: {
                                 content: params[:content]
                              })