Question

我有一些这样的模型：

class LogActivity < ActiveRecord::Base
   has_many :call_logs
   has_many :send_email_logs
   has_many :send_sms_logs
   ...
end

class CallLog < ActiveRecord::Base
   belongs_to :log_activity
end

class SendEmailLog < ActiveRecord::Base
   belongs_to :log_activity
end

class SendSmsLog < ActiveRecord::Base
   belongs_to :log_activity
end

现在，我希望在:call_logs，:send_email_logs，:send_sms_logs中获得一条最新记录。我怎么能这样做？

Answer 1

您可以尝试这样做 -

newest_call_log       = LogActivity.call_logs.last
newest_sent_email_log = LogActivity.send_email_logs.last
newest_sent_sms_log   = LogActivity.send_sms_logs.last

单个查询替代方法是执行此操作 -

newest_log = LogActivity.eager_load(:call_logs, :send_email_logs, :send_sms_logs).last
# The above will fire a query and fetch all the data you need, the below lines will segregate your data
newest_call_log       = newest_log.call_logs.last
newest_sent_email_log = newest_log.send_email_logs.last
newest_sent_sms_log   = newest_log.send_sms_logs.last

Answer 2

您可以尝试如下：

Content-Type

有关详细说明，您可以查看导轨guide link

由于

Rails在许多has_many中获得最新记录

2 个答案: