多选菜单和虚拟属性

Question

我有周期表具有start_at：datetime end_at：datetime。 由于每个周期在同一天开始和结束，我想分开三个字段而不是两个字段。

场1：日期 场2：时间 “00:00” 开始 场3：时间 “00:00” 结束

的，我开始并做到了这一点。但不幸的是，我遇到了一个问题。

所以请看看期间模型，表格和错误，并纠正我，纠正代码。

在此先感谢！

周期模型

class Period < ActiveRecord::Base 
    belongs_to :show 

    def show_date; start_at.nil? ? Time.now.to_date : start_at.to_date; end 
    def start_at_time; start_at.nil? ? Time.now.to_time : start_at.to_time; end 
    def end_at_time; end_at.nil? ? Time.now.to_time : end_at.to_time; end 

    def start_at_time=(start_str) 
    self.start_at = DateTime.parse("#{show_date.strftime("%Y-%m-%d")}T#{start_str.strftime("%H:%M:%S")}") 
    end 

    def end_at_time=(end_str) 
    self.end_at = DateTime.parse("#{show_date.strftime("%Y-%m-%d")}T#{end_str.strftime("%H:%M:%S")}") 
    end 
end 

周期模式

#just the schema for periods table 
    create_table "periods", :force => true do |t| 
    t.integer "show_id" 
    t.datetime "start_at" 
    t.datetime "end_at" 
    t.datetime "created_at" 
    t.datetime "updated_at" 
    end 

_form.html.erb

<div class="group"> 
    <%= f.label :show_id, "Show", :class => :label %> 
    <%= f.collection_select :show_id, @shows.collect, :id, :name %> 
    <span class="description">Select the show</span> 
    </div> 

    <div class="group"> 
    <%= f.label :show_date, "Date at", :class => :label %> 
    <%= f.date_select :show_date, :class => 'datetime_select' %> 
    <span class="description">Date of the show</span> 
    </div> 

    <div class="group"> 
    <%= f.label :start_at_time, "Start at", :class => :label %> 
    <%= f.time_select :start_at_time, {:minute_step => 15, :ignore_date => true}, :class => 'datetime_select' %> 
    <span class="description">Time :: When does it start?</span> 
    </div> 

    <div class="group"> 
    <%= f.label :end_at_time, "End at", :class => :label %> 
    <%= f.time_select :end_at_time, {:minute_step => 15, :ignore_date => true}, :class => 'datetime_select' %> 
    <span class="description">Time :: When does it end?</span> 
    </div> 

    <div> 
    <button class="button" type="submit"><%= image_tag("tick.png", :alt => "Save") %> Save</button> 
    </div> 

的错误

==Framework Trace 

3 error(s) on assignment of multiparameter attributes 



==Framework Trace 

/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:3073:in `execute_callstack_for_multiparameter_attributes' 
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:3028:in `assign_multiparameter_attributes' 
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:2750:in `attributes=' 
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/base.rb:2628:in `update_attributes' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/base.rb:1331:in `send' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/base.rb:1331:in `perform_action_without_filters' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/filters.rb:617:in `call_filters' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/filters.rb:610:in `perform_action_without_benchmark' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue' 
/home/amrnt/.gem/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/core_ext/benchmark.rb:17:in `ms' 
/usr/lib/ruby/1.8/benchmark.rb:308:in `realtime' 
/home/amrnt/.gem/ruby/1.8/gems/activesupport-2.3.5/lib/active_support/core_ext/benchmark.rb:17:in `ms' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/benchmarking.rb:68:in `perform_action_without_rescue' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/rescue.rb:160:in `perform_action_without_flash' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/flash.rb:146:in `perform_action' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/base.rb:532:in `send' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/base.rb:532:in `process_without_filters' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/filters.rb:606:in `sass_old_process' 
/usr/lib/ruby/gems/1.8/gems/haml-2.3.0/lib/sass/plugin/rails.rb:19:in `process_without_compass' 
/home/amrnt/cc/vendor/gems/compass-0.8.17/lib/compass/app_integration/rails/action_controller.rb:7:in `process' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/base.rb:391:in `process' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/base.rb:386:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/routing/route_set.rb:437:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:87:in `dispatch' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:121:in `_call' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:130:in `build_middleware_stack' 
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/query_cache.rb:29:in `call' 
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/query_cache.rb:29:in `call' 
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/query_cache.rb:34:in `cache' 
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/query_cache.rb:9:in `cache' 
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/query_cache.rb:28:in `call' 
/usr/lib/ruby/gems/1.8/gems/activerecord-2.3.5/lib/active_record/connection_adapters/abstract/connection_pool.rb:361:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/string_coercion.rb:25:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/head.rb:9:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/methodoverride.rb:24:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/params_parser.rb:15:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/session/cookie_store.rb:93:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/failsafe.rb:26:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/lock.rb:11:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/lock.rb:11:in `synchronize' 
/home/amrnt/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/lock.rb:11:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:114:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/reloader.rb:34:in `run' 
/home/amrnt/.gem/ruby/1.8/gems/actionpack-2.3.5/lib/action_controller/dispatcher.rb:108:in `call' 
/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/rack/static.rb:31:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/urlmap.rb:46:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/urlmap.rb:40:in `each' 
/home/amrnt/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/urlmap.rb:40:in `call' 
/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/rails/rack/log_tailer.rb:17:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/content_length.rb:13:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/chunked.rb:15:in `call' 
/home/amrnt/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/handler/mongrel.rb:64:in `process' 
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:159:in `process_client' 
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `each' 
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:158:in `process_client' 
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `run' 
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `initialize' 
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `new' 
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:285:in `run' 
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `initialize' 
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `new' 
/usr/lib/ruby/gems/1.8/gems/mongrel-1.1.5/lib/mongrel.rb:268:in `run' 
/home/amrnt/.gem/ruby/1.8/gems/rack-1.0.1/lib/rack/handler/mongrel.rb:34:in `run' 
/usr/lib/ruby/gems/1.8/gems/rails-2.3.5/lib/commands/server.rb:111 
/usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `gem_original_require' 
/usr/local/lib/site_ruby/1.8/rubygems/custom_require.rb:31:in `require' 
script/server:3 



==Request Parameters: 

{"period"=>{"start_at_time(4i)"=>"20", 
"start_at_time(5i)"=>"00", 
"end_at_time(4i)"=>"23", 
"end_at_time(5i)"=>"30", 
"show_date(1i)"=>"2010", 
"show_date(2i)"=>"3", 
"show_date(3i)"=>"31", 
"show_id"=>"1"}, 
"_method"=>"put", 
"authenticity_token"=>"pm/cXQQnOCsidcAj/OEJuMtHgfppZvoqq09epdETAxo=", 
"id"=>"46"} 

Answer 1

ActionView附带的date and time form helpers会生成使用称为“多参数分配”的特殊表单元素。这意味着当您提交date_select,datetime_select或time_select表单字段时，它们会生成几个单独的参数，这些参数由ActiveRecord编译为一个日期，日期时间或时间对象。在你的情况，这些参数是这样的：

"start_at_time(4i)"=>"20", 
"start_at_time(5i)"=>"00" 

"end_at_time(4i)"=>"23", 
"end_at_time(5i)"=>"30" 

"show_date(1i)"=>"2010", 
"show_date(2i)"=>"3", 
"show_date(3i)"=>"31" 

我要指出，这些都是你在你的周期模型start_at_time=和end_at_time=方法和期待串非常不同的模型没有一个show_date=方法在所有。

带括号的参数格式是Rails用于多参数分配的内容。但是，ActiveRecord依赖相应的数据库列来知道提交的多个参数是否代表日期，时间或日期时间对象。这意味着助手不会在虚拟属性上工作，至少是开箱即用的。没有办法告诉他们期望什么样的对象。

有这个至少一个有效票：

https://rails.lighthouseapp.com/projects/8994/tickets/2675-support-for-multiparameter-attribute-assignment-on-virtual-attribute-writers

，你可以找到多参数赋值的一个很好的概述，并在此链接使用日期格式助手使用Rails：

http://www.alexrothenberg.com/2009/05/how-to-use-dates-in-rails-when-your.html

关于对此设计的一般改进：如果每个周期在同一日期开始和结束，为什么不使用date属性来存储周期d吃了两个time属性来存储开始和结束时间。您可以轻松创建一个方法，该方法返回从这些属性编译的start_at和end_at日期时间对象。

您可以使用表单助手或多或少地设置您的表单，因为您已经有了。您还可以轻松设置end_time属性的验证，确保它始终在start_time之后。