＃<位置0x .. =“”>的未定义方法`image'

Question

我正在使用回形针宝石。用户可以使用图像提交位置。我不希望用户复制已经提交的位置，但是他们可以向其中添加图片。

我一直试图找出答案。我将在下面留下重要的代码：

location.rb

class Location < ApplicationRecord
  has_many :submissions
  has_many :users, through: :submissions
  # Allows submission objects
  accepts_nested_attributes_for :submissions

submission.rb

class Submission < ApplicationRecord
  belongs_to :user
  belongs_to :location

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

locations_controller.rb

class LocationsController < ApplicationController

  # Before actions get routed and ran, find_location will occur
  before_action :find_location, only: [:show, :edit, :update, :destroy]


  # For the Locations/index.html.erb
  def index
    @locations = Location.all
  end

  # Binds submission object to the form in new.html.erb
  def new
    @locations = Location.new
    @locations.submissions.build
  end

  # For creating a new location in the new.html.erb form
  def create
    @locations = Location.new(user_params)
    # Everything went well. User will be sent to @locations show page
    if  @locations.save
      # Redirects to user submitted locations
      redirect_to @locations
    else
      render 'new'
    end
  end

  # Finds new location user submitted by its unique id
  def show
  end

  # Allowing user to update their submitted location
  def edit
  end

  # Updates users edited submission
  def update
    if @locations.update(user_params)
      # Redirects to user submitted locations
      redirect_to @locations
    else
      render 'edit'
    end
  end

  # Deletes users submission
  def destroy
    @locations.destroy
    # Redirects to user submitted locations
    redirect_to @locations
  end

  private

  # Used for finding user submitted location (Prevents DRY)
  def find_location
    @locations = Location.find(params[:id])
  end

  # Strong parameters for security - Defines what can be update/created in location model
  def user_params
    params.require(:location).permit(:city, :state, :submissions_attributes => [:image])
  end
end

_form.html.erb

<%= form_for @locations, html: {multipart: true} do |f| %>
.
.
.
<!--  User enters image-->
  <%= f.fields_for :submissions do |s| %>
  <div class="form-group">
    <h3>Upload Image:</h3>
    <%= s.file_field :image, class: 'form-control' %>
  </div>
    <% end %>
<% end %>

show.html.erb

<h3>Image: <%= image_tag @locations.image.url(:medium) %></h3>

我得到一个错误：

"undefined method `image' for.."

Answer 1

您似乎正在尝试为记录的集合制作表单标签，我认为这不起作用。相反，我认为您需要一个类似以下的结构：

<% @locations.each do |location| %>
  <%= form_for location, html: {multipart: true} do |f| %>
  .
  .
  .
  <!--  User enters image-->
  <%= f.fields_for location.submissions.new do |s| %>
    <div class="form-group">
      <h3>Upload Image:</h3>
      <%= s.file_field :image, class: 'form-control' %>
    </div>
  <% end %>
<% end %>

form_for和fields_for都需要指向单个资源。

旁注：Paperclip has been deprecated，建议您改用Rails内部ActiveStorage。