NilClass：Class的未定义方法“ model_name”-Rails应用程序上的ruby

Question

I have form where a user submit a e-mail, its in the view: views/about/home.html.haml

The form looks like this:

 = 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

The controller looks like this:

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

The model looks like this:

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

But I am getting this error:

undefined method `model_name' for NilClass:Class

What is wrong?

Answer 1

You should add

@waitinglist = Waitinglist.new

in the home method of your AboutController . Your form tries to use @waitinglist , but if you don't define it it will be nil and this exception will be thrown.