Add 'Post.permitted_create_params' to allow plugins to add new params when creating a post

app/controllers/posts_controller.rb

@@ -561,6 +561,10 @@ class PostsController < ApplicationController
       :visible
     ]
 
+    if Post.permitted_create_params.present?
+      permitted.concat(Post.permitted_create_params.to_a)
+    end
+
     # param munging for WordPress
     params[:auto_track] = !(params[:auto_track].to_s == "false") if params[:auto_track]
     params[:visible] = (params[:unlist_topic].to_s == "false") if params[:unlist_topic]

app/models/post.rb

@@ -17,6 +17,9 @@ class Post < ActiveRecord::Base
   include HasCustomFields
   include LimitedEdit
 
+  cattr_accessor :permitted_create_params
+  self.permitted_create_params = Set.new
+
   # increase this number to force a system wide post rebake
   BAKED_VERSION = 1