Rails多态关联与表单collection_select没有嵌套答案

【问题标题】：Rails Polymorphic association with form collection_select without nestingRails多态关联与表单collection_select没有嵌套
【发布时间】：2014-04-07 02:17:50
【问题描述】：

我的应用中有以下模型

class User < ActiveRecord::Base
has_many :articles
has_many :tour_companies
has_many :accomodations
end

class Articles < ActiveRecord::Base
belongs_to :user
belongs_to :bloggable, :polymorphic => true
end

class TourCompany < ActiveRecord::Base
belongs_to :user
has_many :articles, :as => :bloggable
end

class Accommodation < ActiveRecord::Base
belongs_to :user
has_many :articles, :as => :bloggable
end

现在我的问题是我希望登录用户能够写一篇文章并使用表单 collection_select 来选择文章应该与他/她的哪个旅游公司或住宿相关联，我该怎么做轨道4？如何从表单集合选择中选择可博客类型和 ID？我不想要嵌套资源

【问题讨论】：

标签： ruby-on-rails-4 polymorphic-associations

【解决方案1】：

从 Rails 4.2 开始，这可以通过rails/globalid 处理。 Rails 的 ActiveJob 使用了这个较新的选项。它使解析和查找的设置非常简单。

首先，检查您的Gemfile.lock 是否有globalid。对于 Rails 5，它已包含在内。

所有的魔法都发生在模型中...

文章型号：

# Use :to_global_id to populate the form
def bloggable_gid
  bloggable&.to_global_id
end

# Set the :bloggable from a Global ID (handles the form submission)
def bloggable_gid=(gid)
  self.bloggable = GlobalID::Locator.locate gid
end

要了解它的作用，请打开rails console。玩弄gid = TourCompany.first.to_global_id 和GlobalID::Locator.locate gid。

现在你的代码的其余部分是库存 Rails 的东西......

文章管理员：

# consider building the collection in the controller.
# For Rails 5, this would be a `before_action`.
def set_bloggables
  @bloggables = TourCompany.all + Accomodation.all
end

# permit :bloggable_gid if you're using strong parameters...
def article_params
  params.require(:article).permit(:bloggable_gid)
end

文章形式：

<%= f.collection_select(:bloggable_gid, @bloggables, :to_global_id, :to_s) %>

如需更多演练，Simple Polymorphic Selects with Global IDs 博客文章会很有帮助。

【讨论】：

很好的答案，我不得不去查找 try 简写 &。多么棒的把戏！
在 2020 年（以及使用 Rails 6），这绝对是正确的答案。谢谢！

【解决方案2】：

所以我终于做到了。我是这样做的在意见/文章/_form.html.erb

<div class="row">
<% bloggable_collection = TourCompany.all.map{|x| [x.title, "TourCompany:#{x.id}"]} +
                          Accomodation.all.map{|x| [x.title, "Accomodation:#{x.id}]}
%>
<p>Select one of your listing this article is associated with</p>
<%= f.select(:bloggable, bloggable_collection,:selected =>"#{f.object.bloggable_type}:#  {f.object.bloggable_id}" ) %>
</div>

然后在文章控制器中

#use regular expression to match the submitted values
def create
bloggable_params = params[:article][:bloggable].match(/^(?<type>\w+):(?<id>\d+)$/)
params[:article].delete(:bloggable)

@article = current_user.articles.build(article_params)
@article.bloggable_id         =  bloggable_params[:id]
@article.bloggable_type       =  bloggable_params[:type]
if @article.save
  redirect_to admin_root_url, :notice => "Successfully created article"
else
  render 'new', :alert => "There was an error"
end
end

它应该可以工作！

【讨论】：