“合并”多个模型。创建“最近的活动”框

你必须:

1. 每个模型的查询元素
2. 以通用格式合并它们
3. 分类和限制

下面是一些代码:

class Activity < Struct.new(:title, :text, :date); end

limit = 10
activities = []
activities += Post.all(:order => 'created_at DESC', :limit => limit).map do |post|
  Activity.new(post.title, post.summary, post.created_at)
end

activities += Planet.all(:order => 'published_at DESC', :limit => limit).map do |planet|
  Activity.new(planet.title, planet.message, planet.published_at)
end

activities += Message.all(:conditions => ['receiver_id = ?', current_user.id], :order => 'created_at DESC', :limit => limit).map do |message|
  Activity.new(message.title, message.text, message.created_at)
end

# descending sort by 'date' field
sorted_activities = activities.sort_by(&:date).reverse

# 10 most recent elements across all models
@activities = sorted_activities[0..(limit-1)]

当然,根据您的模型,您必须更改将哪个方法用作“标题”或“文本”。

但是如果您碰巧需要许多这样的习惯用法,那么应该像我们在中所做的那样使用单表继承。 zena (Rails CMS)。

我将使用代理类。类可以存储ActiveRecord对象引用和排序字段。

class ActivityProxy
  attr_accessor :object, :date
  def initialize(object, date)
    self.object = object
    self.date = date
  end
end

然后加载对象。

activity = []
activity += Post.all(:limit => 10, :order => "created_at DESC").map { |post| ActivityProxy.new(post, post.created_at) }
# and so on with the other objects

最后对对象进行排序

activity.sort_by(&:field)
# => here you have the sorted objects
# and you can iterate them with
activity.each do |proxy|
  proxy.object.id
  # ...
end

创建提要的另一种方法是创建一个将两者结合在一起的视图,然后让视图拥有自己的模型。