ruby-on-rails - 表单中的第一个参数不能包含 nil 或为空 Hartl's Rails 4 Tutorial

Question

我正在学习 Michael Hartl 的 Rails 教程，并且在第 7.3.3 节中遇到了问题。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"

在下面一行:

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

这是我的代码。如果我没有很好地构建这个问题，请告诉我应该如何改进这个问题:我对 StackOverflow 也很陌生

app/views/users/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/ Assets / Controller /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

规范/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

在您的 new.html.erb 中，您已指定 form_for(@user) 这意味着您需要在实例变量 @user 中拥有一些值code> 在调用 new 操作之前。

您可以通过两种方式做到这一点:

一种方法是在 Controller 中定义一个操作 new，该操作将在渲染 new.html.erb 布局之前调用。例如:

def new
  @user = User.new
end

另一种方法是在表单本身中您可以指定类似的内容

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

在 new 操作中定义它是更标准的方法。