Rails 3:在 .js.erb 文件中无法访问实例变量 | 文件中无法访问实例变量

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问题描述

我正在尝试构建一个非常简单的页面，我需要在其中为照片库生成一些动态 JavaScript.一些直觉上很简单的东西，但我正在为此苦苦挣扎.在我的控制器中，我将 Photo 列表构建为 @photos，然后需要为我的 photo.js.erb文件.

I'm trying to build a really simple page, where I need to generate some dynamic JavaScript for a photo gallery. Something intuitively simple, but which I'm struggling with greatly. In my controller I am building a list of Photo as @photos, then need to iterate out some JavaScript for each photo in my photo.js.erb file.

然而，每当我到达我的 .js.erb 文件时，@photos 变量就会变成 nil ......我错过了什么?

However, whenever I reach my .js.erb file, the @photos variable becomes nil... what am I missing?

controllers/photos_controller.rb 文件:

class PhotosController < ApplicationController
  layout "application_photos"
  def category
    @photos = ...(generates collection of Photos)...
  end
end

views/photos/category.html.haml 文件:

= content_for :head do
  // @photos is still initialized at this point
  = javascript_include_tag "photos"

// This partial only loads some more markup, it's inconsequential.
= render :partial => 'default_slideshow'

javascripts/photos.js.erb 文件:

jQuery(function($){
    // Throws NilClass error
    <% puts 'Photos: ' + @photos %>
});

我知道这个问题已经被问过十几次了，但以前接受的答案都没有对我有用.非常感谢任何建议.

I know this question has been asked a dozen times, but none of the previously accepted answers actually worked for me. Any suggestions are greatly appreciated.

`推荐答案`

您需要向服务器发送 js 请求才能访问实例变量.像这样

You need to send js request to the server in order to have access to the instance variable. Something like this

$(function($){
  $.ajax({
    type: "get",
    url: "..."
    })

});

在 views/photos/category.js.erb 文件中:

In views/photos/category.js.erb file:

alert("<%= j @photos %>")

或者您可以使用 gon gem 执行相同操作.

Or you can do the same using gon gem.

app/views/layouts/application.html.erb

<head>
 <title>some title</title>
 <%= include_gon %>
 <!-- include your action js code -->
 ...

你在控制器的动作中加入了这样的东西:

You put something like this in the action of your controller:

@your_int = 123
@your_array = [1,2]
@your_hash = {'a' => 1, 'b' => 2}
gon.your_int = @your_int
gon.your_other_int = 345 + gon.your_int
gon.your_array = @your_array
gon.your_array << gon.your_int
gon.your_hash = @your_hash

gon.all_variables # > {:your_int => 123, :your_other_int => 468, :your_array => [1, 2, 123], :your_hash => {'a' => 1, 'b' => 2}}
gon.your_array # > [1, 2, 123]

gon.clear # gon.all_variables now is {}

从您的 JavaScript 文件访问变量:

Access the varaibles from your JavaScript file:

alert(gon.your_int)
alert(gon.your_other_int)
alert(gon.your_array)
alert(gon.your_hash)

希望能帮到你

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