形式中的第一个参数不能包含nil或者是空的Hartl的Rails 4教程

Question

我正在研究Michael Hartl的Rails教程,我在第7.3.3节遇到了一个问题.我收到此错误消息:

ArgumentError in Users#new
Showing /Users/Anuraag/rails_projects/sample_app/app/views/users/new.html.erb where line #6 raised:
First argument in form cannot contain nil or be empty

当我运行以下rspec时:

bundle exec rspec spec/requests/user_pages_spec.rb -e "signup with invalid information"

在以下行:

<%= form_for(@user) do |f| %>

这是我的代码.如果我没有把它搞清楚,请告诉我如何改进这个问题:我对StackOverflow也很陌生

应用程序/视图/用户/ new.html.erb:

<% provide(:title, 'Sign up') %>
<h1>Sign up</h1>

<div class="row">
  <div class="span6 offset3">
    <%= form_for(@user) do |f| %>
      <%= render 'shared/error_messages' %>

      <%= f.label :name %>
      <%= f.text_field :name %>

      <%= f.label :email %>
      <%= f.text_field :email %>

      <%= f.label :password %>
      <%= f.password_field :password %>

      <%= f.label :password_confirmation, "Confirmation" %>
      <%= f.password_field :password_confirmation %>

      <%= f.submit "Create my account", class: "btn btn-large btn-primary" %>
    <% end %>
  </div>
</div>

应用程序/资产/控制器/ users_controller.rb:

class UsersController < ApplicationController
  def show
    @user = User.find(params[:id])
  end

  def create
    @user = User.new(user_params)
    if @user.save
      # Handle a successful save.
    else
      render 'new'
    end
  end

  private

    def user_params
      params.require(:user).permit(:name, :email, :password,
                                   :password_confirmation)
    end
end

规格/请求/ user_pages_spec.rb

require 'spec_helper'

describe "User pages" do

  subject { page }

  describe "signup page" do
    before { visit signup_path }

    it { should have_content('Sign up') }
    it { should have_title(full_title('Sign up')) }
  end

  describe "profile page" do
    let(:user) { FactoryGirl.create(:user) }
    before { visit user_path(user) }

    it { should have_content(user.name) }
    it { should have_title(user.name) }
  end

  describe "signup" do

    before { visit signup_path }

    let(:submit) { "Create my account" }

    describe "with invalid information" do
      it "should not create a user" do
        expect { click_button submit }.not_to change(User, :count)
      end
    end

    describe "with valid information" do
      before do
        fill_in "Name",         with: "Example User"
        fill_in "Email",        with: "user@example.com"
        fill_in "Password",     with: "foobar"
        fill_in "Confirmation", with: "foobar"
      end

      it "should create a user" do
        expect { click_button submit }.to change(User, :count).by(1)
      end
    end
  end
end

Answer 1

在你的new.html.erb指定中form_for(@user),这意味着你需要@user在调用new动作之前在实例变量中有一些值.

你可以用两种方式做到:

一种方法是new在控制器中定义一个动作,在渲染new.html.erb布局之前调用该动作.例如:

def new
  @user = User.new
end

另一种方式是在你的表单中你可以指定类似的东西

<%= form_for(User.new) do |f| %>

在您的new操作中定义它是更标准的方法.