Ruby on Rails未检测到评论字段

Question

I'm trying to build a very basic Rails app for posting images with a comment. The comment is a required field and the image upload should only go ahead if the comments section has a value, displaying an error message otherwise. The problem I am having is that even when the comments section is filled in it still displays an error saying that it cannot be blank. I have tried adding attr_accessor's with the html field names and database values but it makes no difference.

Posts model

class Post < ActiveRecord::Base
  has_attached_file :picture, styles: { medium: "300x300>", thumb: "100x100>" }
  attr_accessor :picture_file_name
  attr_accessor :post_description

  validates :description, presence: true
end

Posts controller

class PostsController < ApplicationController

  def index
    @posts = Post.all
  end

  def new
    @post = Post.new
  end

  def create
    @post = Post.new params[:post].permit(:description, :picture)

    if @post.save
      redirect_to '/posts'
    else
      render 'new'
    end
  end
end

new.html.erb

 <% if @post.errors.any? %>
  <div id="error_explanation">
    <h2><%= pluralize(@post.errors.count, "error") %> prohibited this post from being     saved:</h2>

    <ul>
    <% @post.errors.full_messages.each do |msg| %>
      <li><%= msg %></li>
    <% end %>
    </ul>
  </div>
<% end %>

<%= form_for @post, :html => { :multipart => true } do |f| %>
  <%= f.label :description %>
  <%= f.text_area :description %>

  <%= f.label :picture %>
  <%= f.file_field :picture %>

  <%= f.submit %>
<% end %> 

Server readout

    => Booting WEBrick
=> Rails 4.0.4 application starting in development on http://0.0.0.0:3000
=> Run `rails server -h` for more startup options
=> Ctrl-C to shutdown server
[2014-04-20 17:59:07] INFO  WEBrick 1.3.1
[2014-04-20 17:59:07] INFO  ruby 2.1.0 (2013-12-25) [x86_64-darwin12.0]
[2014-04-20 17:59:07] INFO  WEBrick::HTTPServer#start: pid=98772 port=3000


Started POST "/posts" for 127.0.0.1 at 2014-04-20 17:59:21 +0100
  ActiveRecord::SchemaMigration Load (0.2ms)  SELECT "schema_migrations".* FROM "schema_migrations"
Processing by PostsController#create as HTML
  Parameters: {"utf8"=>"✓", "authenticity_token"=>"nVrCEAdT+epbltQWR74jtv1weGaq6H7YbWQKFfJNDTw=", "post"=>{"description"=>"test comment", "picture"=>#<ActionDispatch::Http::UploadedFile:0x0000010242f740 @tempfile=#<Tempfile:/var/folders/lm/vrw53rx91831vrh4228m0mfw0000gn/T/RackMultipart20140420-98772-1c9msrz>, @original_filename="dory_2.jpg", @content_type="image/jpeg", @headers="Content-Disposition: form-data; name=\"post[picture]\"; filename=\"dory_2.jpg\"\r\nContent-Type: image/jpeg\r\n">}, "commit"=>"Create Post"}
WARNING: Can't mass-assign protected attributes for Post: description, picture
    app/controllers/posts_controller.rb:12:in `create'
   (0.1ms)  begin transaction
   (0.1ms)  rollback transaction
  Rendered posts/new.html.erb within layouts/application (13.1ms)
Completed 200 OK in 105ms (Views: 65.6ms | ActiveRecord: 0.4ms)

Answer 1

Your params & form look okay

But I would change your strong params to be more conventional:

def create
    @post = Post.new(post_params)
    @post.save
end

private

def post_params
    params.require(:post).permit(:description, :picture)
end

Answer 2

I found the problem. The issue was that I had originally installed the latest version of Paperclip and then downgraded. I had added the following gem while I was searching for a solution

gem 'protected_attributes'

This was causing all required fields not to register they were being filled in, such as in user sign up fields etc. Once that gem was removed it worked just fine.