Question

我正在通过Youtube tutorial在我的网站上安装Paperclip gem。到了最后一步，但它返回了以下错误，不知道我哪里出错..

错误 -

NoMethodError in Houses#index
undefined method `image' for nil:NilClass
<%= image_tag @house.image.url(:medium) %>

包含代码以在index.html.erb中显示图像，所以我放入了：

<%= image_tag @house.image.url(:medium) %>

正如教程指示但它不喜欢那个＆amp;我上传图片并刷新索引页面以查看图片时返回错误。

有人知道我哪里出错吗？

所有相关代码如下：

index.html.erb -

<h2><%= link_to "Add a House", new_house_path %></h2>

<% @houses.each do |house| %>
<div class="house">
<%= image_tag @house.image.url(:medium) %>
<h2><%= house.title %></h2>
<h2>&#163;<%= house.price %></h2>
<p><%= house.description %></p>
</div>
<% end %>

house.rb -

class House < ActiveRecord::Base
validates :title, presence: true
validates :price, presence: true
validates :description, presence: true
validates :image, presence: true

has_attached_file :image, styles: { large: "600x600", medium: "300x300", thumb: "150x150#" }
validates_attachment_content_type :image, content_type: /\Aimage\/.*\Z/
end

new.html.erb

<%= simple_form_for @house, html: { multipart: true } do |form| %>
<%= form.input :title, label: "House title" %>
<%= form.input :price, label: "House price" %>
<%= form.input :description, label: "Describe your house" %>
<%= form.input :image, as: :file, label: "Image of house" %>
<%= form.button :submit %>
<% end %>

houses.controller.erb -

class HousesController < ApplicationController
def index
  @houses = House.page(params[:page]).per(20).order(created_at: :desc)
end

def new
  @house = House.new
end

def create
  @house = House.new(params.require(:house).permit(:title, :price, :description, :image))
  if @house.save
    redirect_to root_path
  else
    render "new"
  end
end

end

尝试安装Paperclip gem时返回错误 - Ruby-on-Rails

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