不同模型的 Rails 新动作

Question

我在 Rails 中遇到了创建操作的问题 - 我的控制器中有以下信息：

ComputerController 
def create
  @computer = Computer.new(computer_params)
  redirect_to computers_path
end

private  
 def computer_params
 require.params(:computer).permit(:computer_name,
 :cpu_tag,:serial,:location,:brand,:model,:ram,:cpu,:os,:warranty,:comments)  
end

然后在我的模型中我有一些验证：

class Computer < ActiveRecord::Base
 validates :computer_name,  uniqueness: true, presence: true,
 length:{maximum: 12} 
 validates :cpu_tag, length: {maximum: 4}, uniqueness: true, 
 :numericality =>   {:only_integer => true}
 validates :serial, presence: true
 validates :location, presence: true
 validates :brand, presence: true
 validates :model, presence: true
 validates :ram, presence: true
 validates :cpu, presence: true
 validates :os, presence: true
 validates :warranty, presence: true
 validates :comments, presence: true
end

视图new.html.erb是：

<div class="row text-center">
 <h2 class = "mimsinfoblackindex">Add A Computer To The Inventory </h2><hr/>

<div class="col-md-3 description_pc text-left">
   <%= form_for @computer do |f|%>  

    <h4 class = "mimsformgreen">
      <%= f.label :computer_name,'Computer Name:'%>
      <%= f.text_field :computer_name%>
    </h4>

    <h4 class = "mimsformblack">
      <%= f.label :cpu_tag, 'Computer Tag:'%>
      <%= f.text_field :cpu_tag%>
    </h4>

    <h4 class = "mimsformblack">
      <%= f.label :serial, 'Serial:'%>
      <%= f.text_field :serial%>
    </h4>

    <h4 class = "mimsformblack">
      <%= f.label :location, 'Location:'%> 
      <%= f.text_field :location%>
    </h4>

    <h4 class = "mimsformblack">
      <%= f.label :brand, 'Brand:'%>
      <%= f.text_field :brand%>
    </h4>

    <h4 class = "mimsformblack">
      <%= f.label :model, 'Model:'%>
      <%= f.text_field :model%>
    </h4>

    <h4 class = "mimsformblack">
      <%= f.label :ram, 'Ram:'%> 
      <%= f.text_field :ram%>
    </h4>

    <h4 class = "mimsformblack">  
      <%= f.label :cpu, 'Processor:'%>
      <%= f.text_field :cpu %>
    </h4>

    <h4 class = "mimsformblack">
      <%= f.label :os, 'Operating System:'%> 
      <%= f.text_field :os%>
    </h4>

    <h4 class = "mimsformblack">
      <%= f.label :warranty, 'Warranty:'%>
      <%= f.text_field :warranty%>
    </h4>

     <h4 class = "mimsformblack">
      <%= f.label :comments, 'Comments:'%>
      <%= f.text_field :comments%>
    </h4>

        <%= f.submit 'Add The Computer'%>
  <% end %>

我已经为我的模型进行了 TDD，我没有任何问题，但是当我提交计算机表单时，我在屏幕上收到一条错误消息：

 wrong number of arguments (0 for 1)
 private  
 def computer_params
  require.params(:computer).permit(:computer_name,:cpu_tag,
  :serial,:location,:brand,:model,:ram,:cpu,:os,:warranty,:comments)  
 end

Answer 1

尝试将您的computer_params 重写为：

private  

def computer_params
  params.require(:computer).permit(:computer_name, :cpu_tag, :serial, :location, :brand, :model, :ram, :cpu, :os, :warranty, :comments)  
end

您的原始代码中的params 和require 似乎颠倒了。

希望对你有帮助！

Answer 2

为了补充答案，您可以使用您的代码进行一些修复：

---

1 验证

定义相同的presence验证时，可以pass multiple arguments（属性）给方法：

#app/models/computer.rb
class Computer < ActiveRecord::Base
   validates :serial, :location, :brand, :model, :ram, :cpu, :os, :warranty, :comments, presence: true
end

---

2 参数

Rails 的 strong params 功能非常具体地说明您需要“要求”一个顶级参数，然后“允许”它的子参数：

def computer_params
  params.require(:computer).permit(:computer_name,:cpu_tag, :serial,:location,:brand,:model,:ram,:cpu,:os,:warranty,:comments)  
end

---

3 个循环

在编程中，最高效的代码获胜。

这意味着您不应该一次又一次地复制一堆代码（使用attributes 方法）：

#app/views/computers/new.html.erb
<%= form_for @computer do |f| %>

    <% @computer.attributes.each do |attr| %>
       <% xtra = "green" if attr == :computer_name %>
       <%= content_tag :h4, class: "misform #{xtra}" do %>
          <%= f.label attr.to_sym, attr.titleize + ":" %>
          <%= f.text_field attr.to_sym %>
       <% end %>
    <% end %>

    <%= f.submit 'Add The Computer'%>
<% end %>

看看清洁度有多高？

---

4 个 HTML 类

你已经使用了这两个类名：

mimsformblack mimsformgreen

看看我的#3推​​荐，你能看出这是多么低效吗？这违反了一个名为 DRY (Don't Repeat Yourself) 的原则，在该原则中，您应该使用尽可能少的代码和尽可能多的功能。

您可以将multiple CSS classes 应用于每个元素，这意味着您将能够执行以下操作：

<div class="mimsform">This will be black</div> 
<div class="mimsform green">This will be green</div>

---

5 创建

当您在 Rails 中创建时，您必须将对象保存到模型中：

def create
  @computer = Computer.new computer_params
  redirect_to computers_path if @computer.save
end

许多新手开发人员不保存他们的新对象，从而阻止他们将数据实际保存到数据库中。