如何访问用户在Ruby on Rails上使用控制器发送的数据 [英] How to access data sent by user using controller on Ruby on Rails

问题描述

我在保存用户发送的数据并在我的视图文件中使用它时出现问题，我找不到其他主题的解决方案。

我的代码通过表单选择日期：

 <％= select（'resource'，'field'，@benchmark .compositions.find（：all）.collect {| u | [u.date_composition]}，：prompt =>'Selected date'）％> 
  

这是我的控制器来获得这个选择：

  def sample_method 
 @resource_field = params [：resource] [：field] 
 end 
  

这是我在routes.rb文件中的行：

  match'benchmark / sample_method /：resource /：field'，：controller => 'benchmarks'，：action => 'sample_method'
  

现在我想在我的视图中使用所选的值，

 <％@resource_field = @ benchmark.find（params [：resource] [：field]）％> 
  

但它说

  ActionView :: Template :: Error（未定义的方法`[]'for nil：NilClass）
  

$ b b

如何使用我选择的值？

解决方案

参数

问题是您尝试访问视图中的 params 哈希

这将不起作用，因为 params 是从请求发送到您网站的 HTTP值 - 只有可用基于每个请求。由于您的视图本质上是另一个请求（类似重定向）， params 在其中不可用

当您收到错误：

未定义方法`[]'for nil：NilClass

这基本上说你在 params 变量上调用 [] 是不可能的，因为此对象 nil （未填充数据）

-

变量

您需要做的是在控制器中设置数据 MVC编程模式（您应该永不必须在视图btw中使用 ActiveRecord 方法：

 ＃app / controllers / your_controller.rb 
 Class YourController< ApplicationController 
 def action 
 @resource_field = @ benchmark.find params [：resource] [：field] 
 end 
 end 
  pre> 
 
 
这应该使您的数据可用，而使用刚刚传递给Rails的 params  
 
I have a problem saving data sent by a user and using it in my view file, and I can't find a solution in other topics.

This is my code to select a date via a form:
<%= select( 'resource', 'field', @benchmark.compositions.find(:all).collect {|u| [u.date_composition] }, :prompt => 'Selected date') %>
This is my controller to get this selection:
 def sample_method
  @resource_field = params[:resource][:field]
end
And this is my line in the routes.rb file:
match 'benchmark/sample_method/:resource/:field', :controller => 'benchmarks', :action => 'sample_method'
Now I'd like to use the selected value in my view, so I put:
<% @resource_field = @benchmark.find(params[:resource][:field]) %>
But it says 
ActionView::Template::Error (undefined method `[ ]' for nil:NilClass)
How can I use my selected value please ?
解决方案
Params

The problem is you're trying to access the params hash in your view

This won't work, as the params are HTTP values sent from a request to your site - only being available on a per-request basis. As your view is essentially another request (kind of like a redirect), the params are not available in there

When you receive the error:

  
undefined method `[ ]' for nil:NilClass
This basically says that your calling of [] on the params variable is not possible, as this object is nil (not populated with data)

--

Variables

What you'll have to do is set your data in your controller, as per the MVC programming pattern (you should never have to use ActiveRecord methods in your views btw):
#app/controllers/your_controller.rb
Class YourController < ApplicationController
   def action
       @resource_field = @benchmark.find params[:resource][:field]
   end
end
This should make this data available in your view, whilst using the params which have just been passed to Rails 

                        
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