为什么我在安装 PaperClip 时得到“has_attached_file"的“未定义方法"? [英] Why do I get an "undefined method for `has_attached_file` when installing PaperClip?

问题描述

我刚刚安装了 Paperclip 插件，但收到以下错误消息，但我不知道为什么:

I just installed the plugin for Paperclip and I am getting the following error message but I am not sure why:

NoMethodError (undefined method `has_attached_file' for #<Class:0x10338acd0>):
  /Users/bgadoci/.gem/ruby/1.8/gems/will_paginate-2.3.12/lib/will_paginate/finder.rb:170:in `method_missing'
  app/models/post.rb:2
  app/controllers/posts_controller.rb:50:in `show'

它引用了 will_paginate gem.据我所知，我的 PostsController#index 似乎有问题，或者之前尝试安装 gem 而不是插件，在这种情况下，我已经阅读了我应该能够以某种方式通过 /config/environments.rb 文件进行补救.

It is referencing the will_paginate gem. From what I can find, it seems that either there is something wrong with my PostsController#index or perhaps a previously attempt at installing the gem instead of the plugin, in which case I have read I should be able to remedy through the /config/environments.rb file somehow.

我不认为以前的 gem 安装会像我在安装插件之前丢弃的旧版本站点中那样重要.在该站点的当前版本中，我显示该表在迁移后已使用 Paperclip 列进行更新.这是我的代码:

I didn't think that previous gem installation would matter as I did it in an old version of the site that I trashed before installing the plugin. In the current version of the site I show that the table has been updated with the Paperclip columns after migration. Here is my code:

PostsConroller#show:

  def show
    @post = Post.find(params[:id])

    respond_to do |format|
      format.html # show.html.erb
      format.xml  { render :xml => @post }
    end
  end

后模型:

class Post < ActiveRecord::Base

  has_attached_file :photo
  validates_presence_of :body, :title
  has_many :comments, :dependent => :destroy
  has_many :tags, :dependent => :destroy
  has_many :votes, :dependent => :destroy
  belongs_to :user
  after_create :self_vote
      def self_vote
       # I am assuming you have a user_id field in `posts` and `votes` table.
       self.votes.create(:user => self.user)
      end

  cattr_reader :per_page 
    @@per_page = 10

end

/views/posts/new.html.erb:

<h1>New post</h1>
<%= link_to 'Back', posts_path %>
<% form_for(@post, :html => { :multipart => true}) do |f| %>
  <%= f.error_messages %>

  <p>
    <%= f.label :title %><br />
    <%= f.text_field :title %>
  </p>
  <p>
    <%= f.label :body %><br />
    <%= f.text_area :body %>
  </p>
  <p>
    <%= f.file_field :photo %>
  </p>

  <p>
    <%= f.submit 'Create' %>
  </p>
<% end %>

推荐答案

在安装新的 gems/插件后重新启动服务器非常重要.这应该可以解决您的问题

It is very important that you restart your server after installing new gems/plugins. This should solve your problem

这篇关于为什么我在安装 PaperClip 时得到“has_attached_file"的“未定义方法"?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！