ruby-on-rails – Rails 3：用户对实体的多态喜好,怎么样？

事实证明,你所建议的几乎与我最终做的事情完全一致(我总是很高兴发现你决定做的是其他人会做的事情,我喜欢它的理智检查价值).

所以这就是我所做的,而且它都是通过回复来完成的.现在我只需要实现AJAX并设置样式：

我最喜欢的模型因为我的Polymorphic Favorites模型要求实体只能被我添加到验证“范围”的用户一次收藏,这表明对于每个属性,它必须在其他2个必需属性的范围内是唯一的.这解决了同一用户的多个收藏夹的问题.

class Favorite < ActiveRecord::Base
  before_save :associate_user

  belongs_to :favorable
  belongs_to :user

  # Validations
  validates :user_id,:presence => true,:uniqueness => {:scope => [:favorable_id,:favorable_type],:message => "item is already in favorites list."}
  validates :favorable_id,:uniqueness => {:scope => [:user_id,:message => "item is already in favorites list."}
  validates :favorable_type,:user_id],:message => "item is already in favorites list."}

  # Callbacks
  protected

  def associate_user
    unless self.user_id
      return self.user_id = session[:user_id] if session[:user_id]
      return false
    end
  end

end

我的用户模型(相关的)：我添加了2个方法,get_favorites与教程中的有利方法和收藏夹相同？检查有问题的实体是否已添加到用户的收藏夹的方法.

class User < ActiveRecord::Base  
  # Relationships
  has_many  :microposts,:dependent => :destroy
  has_many  :favorites

  # Methods
  def favorite?(id,type)
    if get_favorites({:id => id,:type => type}).length > 0
      return true
    end
    return false
  end

  def get_favorites(opts={})
    # Polymorphic Favoritability: allows any model in the
    # application to be favorited by the user.
    # favorable_type
    type = opts[:type] ? opts[:type] : :topic
    type = type.to_s.capitalize

    # add favorable_id to condition if id is provided
    con = ["user_id = ? AND favorable_type = ?",self.id,type]

    # append favorable id to the query if an :id is passed as an option into the
    # function,and then append that id as a string to the "con" Array
    if opts[:id]
      con[0] += " AND favorable_id = ?"
      con << opts[:id].to_s
    end

    # Return all Favorite objects matching the above conditions
    favs = Favorite.all(:conditions => con)

    case opts[:delve]
    when nil,false,:false
      return favs
    when true,:true
      # get a list of all favorited object ids
      fav_ids = favs.collect{|f| f.favorable_id.to_s}

      if fav_ids.size > 0
        # turn the Capitalized favorable_type into an actual class Constant
        type_class = type.constantize

        # build a query that only selects
        query = []
        fav_ids.size.times do
          query << "id = ?"
        end
        type_conditions = [query.join(" AND ")] + fav_ids

        return type_class.all(:conditions => type_conditions)
      else
        return []
      end
    end
  end

end

我的Micropost模型(相关的)：注意has_many关系中的Polymorphic关联标题为：favorites.

class Micropost < ActiveRecord::Base
  attr_accessible :content

  # Scopes
  default_scope :order => 'microposts.created_at DESC'

  # Relationships
  belongs_to  :user
  has_many  :favorites,:as => :favorable # Polymorphic Association

  # Validations
  validates :content,:length => { :minimum => 1,:maximum => 140 }
  validates :user_id,:presence => true

end

我的Micropost表单：正如您所看到的那样,我将作为本地变量映射到Favorite模型的实体传递给2 Favorite表单作为’local_entity’.这样我就可以为多态关联提取ID和实体的TYPE.

<div class="post">
    <span class="value">
      <%= micropost.content %>
    </span>
    <span>
        <% if current_user.favorite?(micropost.id,micropost.class.to_s) %>
            <%= render :partial => 'favorites/remove_favorite',:locals => {:local_entity => micropost} %>
        <% else %>
            <%= render :partial => 'favorites/make_favorite',:locals => {:local_entity => micropost} %>
        <% end %>
    </span>
    <span class="timestamp">
        Posted <%= time_ago_in_words(micropost.created_at) %> ago.
    </span>
    <div class="clear"></div>
</div>

我最喜欢的表格：

<%= form_for current_user.favorites.build do |f| %>
    <div><%= f.hidden_field :favorable_id,:value => local_entity.id %></div>
    <div><%= f.hidden_field :favorable_type,:value => local_entity.class.to_s %></div>
    <div class="actions"><%= f.submit "make favorite" %></div>
<% end %>

我删除最喜欢的表格：

<%= form_for current_user.get_favorites(
                     {:id => local_entity.id,:type => local_entity.class.to_s}),:html => { :method => :delete } do |f| %>
    <div class="actions"><%= f.submit "remove favorite" %></div>
<% end %>