Question

我发布新派对时收到以下错误消息：派对模型缺少attr_accessor需要＆＃39; image_file_name＆＃39; ，它指向我的parties_controller.rb中的代码：< BR />

def create
    @party = Party.new(party_params)

我很难理解这个错误的原因，

这是我正在使用的其他代码

party.rb

class Party < ActiveRecord::Base
        belongs_to :user
        has_attached_file :image, :styles => { :medium => "300x300>", :thumb => "100x100>" }
    validates :description, presence: true
    validates :image, presence: true
    end

parties_controller.rb

class PartiesController < ApplicationController
  before_action :set_party, only: [:show, :edit, :update, :destroy]
  # GET /parties
  # GET /parties.json
  def index
    @parties = Party.all
  end
  # GET /parties/1
  # GET /parties/1.json
  def show
  end
  # GET /parties/new
  def new
    @party = Party.new
  end
  # GET /parties/1/edit
  def edit
  end
  # POST /parties
  # POST /parties.json
  def create
    @party = Party.new(party_params)
    respond_to do |format|
      if @party.save
        format.html { redirect_to @party, notice: 'Party was successfully created.' }
        format.json { render :show, status: :created, location: @party }
      else
        format.html { render :new }
        format.json { render json: @party.errors, status: :unprocessable_entity }
      end
    end
  end
  # PATCH/PUT /parties/1
  # PATCH/PUT /parties/1.json
  def update
    respond_to do |format|
      if @party.update(party_params)
        format.html { redirect_to @party, notice: 'Party was successfully updated.' }
        format.json { render :show, status: :ok, location: @party }
      else
        format.html { render :edit }
        format.json { render json: @party.errors, status: :unprocessable_entity }
      end
    end
  end
  # DELETE /parties/1
  # DELETE /parties/1.json
  def destroy
    @party.destroy
    respond_to do |format|
      format.html { redirect_to parties_url, notice: 'Party was successfully destroyed.' }
      format.json { head :no_content }
    end
  end
  private
    # Use callbacks to share common setup or constraints between actions.
    def set_party
      @party = Party.find(params[:id])
    end
    # Never trust parameters from the scary internet, only allow the white list through.
    def party_params
      params.require(:party).permit(:latitude, :longitude, :address, :description, :title, :image)
    end
end

user.rb

class User < ActiveRecord::Base
  # Include default devise modules. Others available are:
  # :confirmable, :lockable, :timeoutable and :omniauthable
  devise :database_authenticatable, :registerable, #:confirmable,
         :recoverable, :rememberable, :trackable, :validatable

  has_many :parties

  validates :name, presence: true
  #validates :email, format: { with: /\A([^@\s]+)@((?:[-a-z0-9]+\.)+edu)\z/ }
end

Answer 1

发生此错误的原因是在db / migrations文件中创建了重复的迁移文件。您需要做的是删除所有这些文件，然后在终端上执行rake db：rollback以取消所有迁移。然后做一个rails d paperclip MODEL（用模型u r替换名称）图像。然后做一个rails g paperclip MODEL图像然后rake db：migrate。它现在应该工作

Answer 2

首先，您的image_file_name不应该是attr_accessor - 它应该是您party对象的实际属性（@party.image_file_name）

考虑到您已使用Paperclip执行了所需的migrations设置db，我相信问题可能出在以下问题：

validates :image, presence: true

我相信你会更好地使用内置的Paperclip AttachmentPresenceValidator，如下所示：

   class Party < ActiveRecord::Base
        has_attached_file :image, :styles => { :medium => "300x300>", :thumb => "100x100>" }
        validates_attachment_presence :image
    end

原因是当您将image对象传递给Party模型时，您不会发送“裸”对象。 Paperclip在通过之前为对象分配了各种属性，这就是为什么你看到attr_accessor错误（Paperclip在保存之前分配属性，因此它必须使用attr_accessor来创建它们）

使用内置的validates_attachment方法，您可以直接验证Paperclip对象

模型缺少'image_file_name'所需的attr_accessor - Ruby on Rails 4

2 个答案: