调整应用的修改功能，使其可以更新重新上传的文件，但是会删除上次上传的文件

app/controllers/softapplications_controller.rb

@@ -76,7 +76,8 @@ class SoftapplicationsController < ApplicationController
   # PUT /softapplications/1.json
   def update
     # @softapplication = Softapplication.find(params[:id])
-
+    @softapplication.attachments.map{|attach| attach.destroy }
+    @softapplication.save_attachments(params[:attachments])
     respond_to do |format|
       if @softapplication.update_attributes(params[:softapplication])
         format.html { redirect_to @softapplication, notice: 'Softapplication was successfully updated.' }