我正在研究＆＃34; Rails：Up＆amp;跑步，第2版。＆＃34;，http://shop.oreilly.com/product/9780596522018.do。我是Javascript的新手，对Rails中的关联经验有限。
我正在尝试使用Rails 4中的jQuery而不是原始中使用的Prototype来实现幻灯片循环。
当我从＆＃39; show.rs.erb＆＃39;调用show_slide操作时，Rails没有看到关联：
NoMethodError (undefined method `slides' for #<Hash:0x007f8f71d49a60> Did you mean? slice slice!)
使用pry我可以看到session[:slideshow]和session[:slide_index]包含正确的值。
我很感激任何建议。
谢谢！
**雷
def show
@slideshow = Slideshow.find(params[:id])
session[:slideshow_id] = params[:id]
session[:slide_index] = 0
@slide = @slideshow.slides[0]
end
def show_slide
@slideshow = Slideshow.find(session[:slideshow_id])
session[:slide_index] += 1
@slide = @slideshow.slides[session[:slide_index]]
if @slide == nil
session[:slide_index] = 0
@slide = @slideshow.slides[0]
end
render :partial => "show_slide"
end
show.js.erb：
$(document).ready(
function(){
setInterval(function(){
$('#slides').load('/show_slide');
}, 2000);
});
幻灯片＃show_slide：
def show_slide
@slideshow = session[:slideshow]
session[:slide_index] += 1
# binding.pry
@slide = @slideshow.slides[session[:slide_index]] # => NoMethodError (undefined method `slides' for #<Hash:0x007f8f71d49a60> Did you mean? slice slice!)
if @slide == nil
session[:slide_index] = 0
@slide = @slideshow.slides[0]
end
render :partial => "show_slide"
end
＆＃34; slideshow.slides＆＃34;关联适用于views / slideshows / index.html.erb：
<% for slideshow in @slideshows %>
<div class="slideshow-summary">
<div class="slideshow-caption">
<strong><%= slideshow.name %> </strong>
<small>(<%= slideshow.slides.size %> slides)</small>
</div>
<div class="slideshow-thumbnails">
<% 5.times do |i| -%>
<%= thumbnail_tag slideshow.slides[i] %>
<% end -%>
<strong>. . .</strong>
</div>
<div class="slideshow-controls">
<%= link_to 'Play', slideshow, :remote => true %>
<%= link_to 'Edit', edit_slideshow_path(slideshow) %>
<%= link_to 'Delete', slideshow, :confirm => 'Are you sure?', :method => :delete %>
</div>
</div>
<br />
<% end %>
但不在这里：
# class SlideshowsController < ApplicationController
def show_slide
@slideshow = session[:slideshow]
session[:slide_index] += 1
# binding.pry
@slide = @slideshow.slides[session[:slide_index]] # NoMethodError (undefined method `slides' for #<Hash:0x007fa574ac11d0> Did you mean? slice slice!)
if @slide == nil
session[:slide_index] = 0
@slide = @slideshow.slides[0]
end
render :partial => "show_slide"
end
show_slide.html.erb：
<%= image_tag "photos/#{@slide.photo.filename}" %>
<h4><%= get_photo_name_from_filename(@slide.photo) %></h4>
show.html.erb：
<p><i><%= @slideshow.name %></i></p>
<% if @slide %>
<div id="slides">
<%= render :partial => "show_slide"%>
</div>
<% end %>
幻灯片＃显示：
# class SlideshowsController < ApplicationController
def show
@slideshow = Slideshow.find(params[:id])
session[:slideshow] = @slideshow
session[:slide_index] = 0
@slide = @slideshow.slides[0]
end
型号：
class Slideshow < ActiveRecord::Base
has_many :slides
end
class Photo < ActiveRecord::Base
has_many :slides
has_and_belongs_to_many :categories
validates_presence_of :filename
scope :with_filetype_jpg, lambda {{:conditions => "filename like '%.jpg'" }}
scope :with_thumbnail, lambda {{:conditions => "thumbnail not null and thumbnail != ''"}}
scope :with_filetype,
lambda {|ftype| {:conditions => ["filename like ?", "%.#{ftype}"] } }
end
class Slide < ActiveRecord::Base
belongs_to :slideshow
belongs_to :photo
acts_as_list :scope => "slideshow_id"
end
的Gemfile：
source 'https://rubygems.org'
gem 'rails', '4.2.5.2'
gem 'sqlite3'
gem 'sass-rails', '~> 5.0'
gem 'uglifier', '>= 1.3.0'
gem 'coffee-rails', '~> 4.1.0'
gem 'jquery-rails'
gem 'turbolinks'
gem 'jbuilder', '~> 2.0'
gem 'sdoc', '~> 0.4.0', group: :doc
group :development, :test do
gem 'byebug'
end
group :development do
gem 'better_errors'
gem 'binding_of_caller'
gem 'meta_request'
gem 'pry-rails'
gem 'spring'
end
gem 'bootstrap-sass'
gem 'bootstrap-generators', '~> 3.3.4'
gem 'acts_as_list'
gem 'acts_as_tree'
调试器会话：
slideshows_controller.rb @ line 15 SlideshowsController#show:
12: def show
13: @slideshow = Slideshow.find(params[:id])
14: session[:slideshow] = @slideshow
=> 15: binding.pry
16: session[:slide_index] = 0
17: @slide = @slideshow.slides[0]
18: end
[1] pry(#<SlideshowsController>)> @slideshow
=> #<Slideshow:0x007f86dce8c320
id: 1,
name: "Interesting Pictures",
created_at: Thu, 24 Mar 2016 21:03:56 UTC +00:00,
updated_at: Thu, 24 Mar 2016 21:03:56 UTC +00:00>
[2] pry(#<SlideshowsController>)> session[:slideshow]
=> #<Slideshow:0x007f86dce8c320
id: 1,
name: "Interesting Pictures",
created_at: Thu, 24 Mar 2016 21:03:56 UTC +00:00,
updated_at: Thu, 24 Mar 2016 21:03:56 UTC +00:00>
[3] pry(#<SlideshowsController>)> exit
slideshows_controller.rb @ line 23 SlideshowsController#show_slide:
21: def show_slide
22: @slideshow = session[:slideshow]
=> 23: binding.pry
24: session[:slide_index] += 1
25: @slide = @slideshow.slides[0]
26: # @slide = @slideshow.slides[session[:slide_index]]
27: if @slide == nil
28: session[:slide_index] = 0
29: @slide = @slideshow[:slides][0]
30:
31: # @slide = @slideshow.slides[0]
32: end
33: render :partial => "show_slide"
34: end
[1] pry(#<SlideshowsController>)> @slideshow
=> {"id"=>1,
"name"=>"Interesting Pictures",
"created_at"=>"2016-03-24T21:03:56.000Z",
"updated_at"=>"2016-03-24T21:03:56.000Z"}
[2] pry(#<SlideshowsController>)> session[:slideshow]
=> {"id"=>1,
"name"=>"Interesting Pictures",
"created_at"=>"2016-03-24T21:03:56.000Z",
"updated_at"=>"2016-03-24T21:03:56.000Z"}
[3] pry(#<SlideshowsController>)>
答案 0 :(得分：0)
如果@slideshow是哈希，则需要使用密钥访问其内容（例如，不像在javascript中那样使用点符号）。
@slideshow[:some_key]
修改
但在您的情况下，您需要一个模型实例，因此您实际上希望从数据库而不是从会话对象加载@slideshow。
将幻灯片的ID存储在会话中（假设您需要跨请求访问它），然后在后续请求中通过该ID读取数据库。
您还可以在会话中存储幻灯片中所需的任何相关信息，并避免每次都从数据库中读取。但总的来说，你要小心你在会话中存储的内容。请参阅Rails session security。