Question

我在使这些多态关联完全正常工作时遇到了一些麻烦。我遵循了本教程www.railscasts.com/episodes/154-polymorphic-association，但这似乎只有在我发布新帖子时我是路径/控制器/ ID＃/注释时才有效。如果我尝试在/ controller / ID＃上呈现部分注释表单，则在创建注释时会出现此错误：

undefined method `comments' for #<ActiveSupport::HashWithIndifferentAccess:0x10341b2d0>

我有三种模式：

class Comment < ActiveRecord::Base
    belongs_to :commentable, :polymorphic => true       
end


class Post < ActiveRecord::Base
    belongs_to :user
    has_many :comments, :as => :commentable
end

class Article < ActiveRecord::Base
    belongs_to :user
    has_many :comments, :as => :commentable
end

这是我对/ articles /＃{ID}

的看法

<%= @article.title %>
<%= @article.content %>
<%= @article.user.login %>
<%= link_to 'Edit Article', edit_article_path(@article) %>

<h2>Comments</h2>
<%= render "comments/comments" %>
<%= render "comments/comment" %>

这是我的评论部分：

<div class="post_comment">
<%= form_for [@commentable, Comment.new] do |f| %>
    <%= f.text_area :content %>
    <%= f.submit "Post" %>
<% end %>
</div>

这是我在评论控制器中的创建方法：

def create
    @commentable = find_commentable
    @comment = @commentable.comments.build(params[:comment])
    @comment.user_id = current_user.id
    if @comment.save
        redirect_to :id => nil
    else    
        flash[:notice] = "something went wrong"
        redirect_to @commentable
    end 
end

def find_commentable
    params.each do |name, value|
        if name =~ /(.+)_id$/
            return $1.classify.constantize.find(value)
        end
    end
end

我想我明白这个问题是什么，但不知道如何解决问题。此表单正在寻找@commentable，但如果路径未嵌套，则无法找到@commentable（可能是错误的）。

以下是我的路线：

devise_for :users do
        get "login", :to => "devise/sessions#new"
        get "register", :to => "devise/registrations#new"
    end

    resources :posts do
        resources :comments
        resources :tags
    end

    resources :articles do
        resources :comments
        resources :tags
    end

    resources :users do 
        resources :articles
        resources :comments
        resources :tags
        resources :posts
    end 

    resources :comments

    root :to => "home#index"

end

Answer 1

你的问题是find_commentable返回params散列本身，因为return语句从未被触发过。

我通过错误消息推断出这一点，因为params.class == ActiveSupport::HashWithIndiffrentAccess

def find_commentable
    params.each do |name, value|
        if name =~ /(.+)_id$/
            return $1.classify.constantize.find(value)
        end
    end
end

我会添加类似

的内容

def find_commentable
    params.each do |name, value|
        if name =~ /(.+)_id$/
            return $1.classify.constantize.find(value)
        end
    end
    raise ActiveRecord:NoRecord.new("Couldn\'t find it captain!")
end

我认为上面的异常类型是正确的，如果没有看到什么Comment.find_by_id（-1）或类似的东西引发。应该是这样的。

修改

我建议引发异常的原因是因为ApplicationController应该捕获这些并在人们开始调整时优雅地处理它们并转到example.com/posts/9001

Answer 2

devise_for :users do
        get "login", :to => "devise/sessions#new"
        get "register", :to => "devise/registrations#new"
    end

    resources :posts do
        resources :comments
        resources :tags
    end

    resources :articles do
        resources :comments
        resources :tags
    end

    resources :users do 
        resources :articles
        resources :comments
        resources :tags
        resources :posts
    end 

    #REMOVE IT resources :comments

    root :to => "home#index"

end

并添加

def index
    @commentable = find_commentable #this
    @comments = @commentable.comments

    respond_to do |format|
      format.html # index.html.erb
      format.json { render json: @comments }
    end
  end

与注释的多态关联 - Ruby on Rails

2 个答案:

修改