ruby-on-rails - NilClass:Class 的未定义方法“model_name” - ruby​​ on rails 应用程序

Question

我有用户提交电子邮件的表单，它在视图中：views/about/home.html.haml

表格如下所示：

 = form_for @waitinglist do |f|
   = f.email_field :email, placeholder: "Enter your email", autofocus: :true
   = button_tag class: "btn btn-large btn-block btn-primary sigin-button" do
     %p Put me on the waiting list

控制器如下所示：

class WaitinglistsController < ApplicationController
  def create
    @waitinglist = Waitinglist.new(params[:waitinglist])
    if @waitinglist.save
        redirect_to root_path
    else
        render action: :new
    end
  end

  def new
    @waitinglist = Waitinglist.new
  end
end

该模型如下所示：

class Waitinglist < ActiveRecord::Base
  attr_accessible :email
  validates :email, presence: true
end

但我收到此错误：

undefined method `model_name' for NilClass:Class

怎么了？

Answer 1

你应该添加

@waitinglist = Waitinglist.new

在home你的方法中AboutController。您的表单尝试使用@waitinglist，但如果您不定义它，它将nil被抛出，并且将引发此异常。