Question

我在下面的代码中遇到了两个问题，

我正尝试做@products.each do |product|，但它让我退缩了undefined nill class on product-我已经检查了产品控制器中的问题，但仍未定义。
当我尝试从下面的简单表单创建新产品，但它似乎没有保存到数据库中时，是因为设计问题吗？（它在url链接上显示了对令牌进行身份验证等），这就是它在url中显示的内容：

How to replace text in Google Spreadsheet using App Scripts?

class Product < ApplicationRecord
  belongs_to:user
  validates :product_name, presence: true, uniqueness: true
end

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

  has_many:products
    validates :name, presence: true, uniqueness: true

  def show
    @user = User.new
  end
end

class UsersController < ApplicationController

  def show
    @user = User.new
  end
end

  <div id='container'>
  <div class='signup_create_product'>
     <form>

<h1>Create a new product</h1>
      <%= simple_form_for @product do |f| %>
       <%= f.input :product_name,
                required: true,
                autofocus: true,
                input_html: { autocomplete: "product_name" }%>

   <%= f.input :condition,
                required: true,
                autofocus: true,
                input_html: { autocomplete: "condition" }%>

    <%= f.input :description,
                required: true,
                autofocus: true,
                input_html: { autocomplete: "description" }%>

         <div class="form-actions">
                <%= f.button :submit, "Submit" %>
              </div>
            <% end %>

     </form>
  </div>
  <div class='whysign'>
    <h1>Share your beloved products with all over the world!</h1>
    <p>This is an Airbnb style platform that you can create your own products and sell it or purchase from all over the world!</p>

    <i class="fas fa-home"></i><%= link_to 'home',root_path  %>


</div>

  </div>

class ApplicationController < ActionController::Base
  # [...]
  before_action :configure_permitted_parameters, if: :devise_controller?

  def configure_permitted_parameters
    # For additional fields in app/views/devise/registrations/new.html.erb
    devise_parameter_sanitizer.permit(:sign_up, keys: [:first_name, :last_name])

    # For additional in app/views/devise/registrations/edit.html.erb
    devise_parameter_sanitizer.permit(:account_update, keys: [:username])
  end
end

class ProductsController < ApplicationController

  def index
    @products = Product.all
  end

  def show
    @product = Product.find(params[:id])
  end

  def new
    @product = Product.new
  end

  def create
    @product = Product.new(product_params)

    if @product.save
      redirect_to product_path(@product)
    else
      render :new
    end
  end

  def edit
    @product = Product.find(params[:id])
  end

  def update
    @product = Product.find(params[:id])
    if @product.update(product_params)
      redirect_to product_path(@cocktail)
    else
      render :edit
    end
  end

  def destroy
    @product = Product.find(params[:id])
    @product.destroy
    redirect_to products_path
  end

  private

  def product_params
    params.require(:product).permit(:product_name, :description)
  end
end

Answer 1

这是导致问题的原因

def show
    @user = User.new
  end

从用户模型和用户控制器中删除

并在产品控制器中

def update
    @product = Product.find(params[:id])
    if @product.update(product_params)
      redirect_to product_path(@cocktail)
    else
      render :edit
    end
  end

在哪里获得实例变量@coctail，它应该是@product

并且由于您不允许产品控制器中的条件，我想您不需要

<%= f.input :condition,
                required: true,
                autofocus: true,
                input_html: { autocomplete: "condition" }%>

并更新

<div id='container'>
  <div class='signup_create_product'>
     <form>

<h1>Create a new product</h1>
      <%= simple_form_for @product do |f| %>
       <%= f.input :product_name,
                required: true,
                autofocus: true,
                input_html: { autocomplete: "product_name" }%>

   <%= f.input :condition,
                required: true,
                autofocus: true,
                input_html: { autocomplete: "condition" }%>

    <%= f.input :description,
                required: true,
                autofocus: true,
                input_html: { autocomplete: "description" }%>

         <div class="form-actions">
                <%= f.button :submit, "Submit" %>
              </div>
            <% end %>

     </form>
  </div>
  <div class='whysign'>
    <h1>Share your beloved products with all over the world!</h1>
    <p>This is an Airbnb style platform that you can create your own products and sell it or purchase from all over the world!</p>

    <i class="fas fa-home"></i><%= link_to 'home',root_path  %>


</div>

  </div>

使用

<div id='container'>
  <div class='signup_create_product'>


<h1>Create a new product</h1>
      <%= simple_form_for @product do |f| %>
       <%= f.input :product_name,
                required: true,
                autofocus: true,
                input_html: { autocomplete: "product_name" }%>

   <%= f.input :condition,
                required: true,
                autofocus: true,
                input_html: { autocomplete: "condition" }%>

    <%= f.input :description,
                required: true,
                autofocus: true,
                input_html: { autocomplete: "description" }%>

         <div class="form-actions">
                <%= f.button :submit, "Submit" %>
              </div>
            <% end %>


  </div>
  <div class='whysign'>
    <h1>Share your beloved products with all over the world!</h1>
    <p>This is an Airbnb style platform that you can create your own products and sell it or purchase from all over the world!</p>

    <i class="fas fa-home"></i><%= link_to 'home',root_path  %>


</div>

  </div>

Answer 2

这里发生了几件事，但是请仔细检查，关于“未定义nil类”的错误很可能与实例变量@projects有关，而不是与迭代变量project有关。也就是说，@projects未定义（或您尝试定义它，并且未返回任何实际记录）。例如，如果您尚未创建任何项目，显然Project.all将返回nil，因此each不会有任何迭代。

尝试使用byebug来检查控制器中用于索引操作的情况。

关于您的第二个问题，这里不应该讨论Devise，因为Project并不是Devise模型。但是，您上面包含的代码在顶部附近有一条虚假的<form>行-这很可能与您稍后创建的form_tag冲突。

未定义的方法为nil类创建产品/

2 个答案: