Question

在我的Rails 3.2应用程序中，连接器has_many事件。

要获取某个连接器的所有事件，我可以这样做：（在控制台中）

c = Connector.find(1) # c.class is Connector(id: integer, name: string, ...
i = c.incidents.all # all good, lists incidents of c

但是如何才能获得许多连接器的所有事件？

c = Connector.find(1,2) # works fine, but c.class is Array
i = c.incidents.all #=> NoMethodError: undefined method `incidents' for #<Array:0x4cc15e0>

应该很容易！但我不明白！

这是我的statistics_controller.rb中的完整代码

class StatisticsController < ApplicationController
  def index

    @connectors = Connector.scoped

    if params['connector_tokens']
      logger.debug "Following tokens are given:  #{params['connector_tokens']}"
      @connectors = @connectors.find_all_by_name(params[:connector_tokens].split(','))
    end

    @start_at = params[:start_at] || 4.weeks.ago.beginning_of_week
    @end_at = params[:end_at] || Time.now


    #@time_line_data = Incident.time_line_data( @start_at, @end_at, 10) #=> That works, but doesn’t limit the result to given connectors
    @time_line_data = @connectors.incidents.time_line_data( @start_at, @end_at, 10) #=> undefined method `incidents' for #<ActiveRecord::Relation:0x3f643c8>
    respond_to do |format|
      format.html # index.html.haml
    end
  end
end

参考下面的前3个答案进行编辑：

大！使用下面的代码，我得到一个包含给定连接器的所有事件的数组。

c = Connector.find(1,2)
i = c.map(&:incidents.all).flatten

但是理想我想获得一个Active Records对象而不是数组，因为我想调用它上面的where（），你可以在下面的方法time_line_data中看到。

我可以通过阵列实现我的目标，但我需要改变整个战略......

这是事件模型models / incidents.rb中的time_line_data()

      def self.time_line_data(start_at = 8.weeks.ago, end_at = Time.now, lim = 10)
        total = {}
        rickshaw = []
        arr = []
        inc = where(created_at: start_at.to_time.beginning_of_day..end_at.to_time.end_of_day)

        # create a hash, number of incidents per day, with day as key
        inc.each do |i|
          if total[i.created_at.to_date].to_i > 0
            total[i.created_at.to_date] += 1
          else
            total[i.created_at.to_date] = 1
          end
        end
        # create a hash with all days in given timeframe, number of incidents per day, date as key and 0 as value if no incident is in database for this day
        (start_at.to_date..end_at.to_date).each do |date|
          js_timestamp = date.to_time.to_i
          if total[date].to_i > 0
            arr.push([js_timestamp, total[date]])
            rickshaw.push({x: js_timestamp, y: total[date]})
          else
            arr.push([js_timestamp, 0])
            rickshaw.push({x: js_timestamp, y: 0})
          end
        end

        { :start_at => start_at,
          :end_at => end_at,
          :series => rickshaw #arr


}
end

Answer 1

参考： - map

c = Connector.find(1,2)
i = c.map(&:incidents.all).flatten

Answer 2

由于您似乎只对时间线数据感兴趣，您可以进一步扩展之前给出的地图示例：

@time_line_data = @connectors.map do |connector|
  connector.incidents.map do |incident|
    incident.time_line_data(@start_at, @end_at, 10)
  end
end

这将映射/收集time_line_data方法调用的所有返回值，用于连接器集合中的所有事件。

嵌套的ActiveRecords：找到许多父母的许多孩子

参考下面的前3个答案进行编辑：

2 个答案: