如何创建一个简单的活动流？

Question

我正在尝试实现一个简单的活动流。

Given that User abc creates a post 123
And User xyz comments on 123.  
Then user abc's activity stream should look something like:
<ul>
  <li>User <a href="/users/abc">abc</a> created a post <a href="/users/abc/posts/123">123</a></li>
  <li>User <a href="/users/xyz">xyz</a> commented on post <a href="/users/abc/posts/123">123</a></li>
</ul>

我更喜欢填充活动模型（而不是控制器中的多个查询）。我在帖子和 cmets 模型中添加了一个“after_create”钩子来填充活动：

class Post < ActiveRecord
  after_create do
    ActivityCreate(:user_id => self.user_id, :description => "created a post")
  end
end

我想存储创建路线和链接所需的特殊字段，例如 post_id 等，但我以后可能有更多想要跟踪的活动，喜欢、不喜欢、收藏夹等，我想要一个灵活的创建活动描述的方式。

所以我的问题是，将 link_to 放入活动描述的有效方法是什么？是否有任何 c 样式的 printf 方式列出稍后评估的助手？

有点像这样：

description = ["用户？评论了帖子？"，user_path(User.find(self.user_id))，post_path(Post.find(self.id))]

然后在模板端评估这个？

Answer 1

这是我第一次联想到你的案子。也许它足够激励你:)

class Activity < ActiveRecord::Base
  #this might be a comment or a post or something else
  belongs_to :changed_item, :polymorphic => true
  #who did it?
  belongs_to :user
  #what did he do?
  validates_presence_of :changes

  def msg
    #do fancy text generation
    if changes.new_record
      "#{user.name} created a #{changed_item.class}"
    else
      "#{user.name} changed #{changes.length} attributes of the #{changed_item.class} #{changed_item.title}"
    end
  end

  def initialize(model, user)
    #fetch changes and remember user and changed model
    self.changed_item = model
    self.user = user
    self.changes << model.changed_attributes.merge({:new_record => model.new_record?})
  end
end

class Post < ActiveRecord::Base
  after_save do
    #remember who to be blamed
    Activity.create(self, current_user)
  end
end

class User < ActiveRecord::Base
  #the users activities
  has_many :activities
end