Rails accept_nested_attributes_for回调 [英] Rails accepts_nested_attributes_for callbacks

问题描述

我有两个模型 Ticket 和 TicketComment ，TicketComment是Ticket的子代。

ticket.rb

  ; ActiveRecord :: Base 
 has_many：ticket_comments，：dependent => ：destroy，：order => 'created_at DESC'
 
＃允许从票单内创建票证注释
 accepts_nested_attributes_for：ticket_comments，：reject_if => proc {| attributes | attributes ['comment']。blank？ } 
 end 
  

ticket_comment.rb

  class TicketComment< ActiveRecord :: Base 
 belongs_to：ticket 
 
 validates_presence_of：comment 
 end 
  

b $ b

我想要做的是模仿Trac中的功能，其中如果用户更改票证和/或添加评论，电子邮件将发送给分配给票证的人员。 p>

我想使用after_update或after_save回调，以便我知道在发送电子邮件之前所有的信息都已保存。

如何检测对模型（ticket.changes）的更改以及是否创建了新评论（ticket.comments），并将此更新（x更改为y，用户添加了评论text）发送到回调方法中有一封电子邮件？

解决方案

您可以使用 ActiveRecord :: Dirty 模块，您可以跟踪未保存的更改。

  t1 = Ticket.first 
 t1.some_attribute = some_new_value 
 t1.changed？ => true 
 t1.some_attribute_changed？ => true 
 t1.some_attribute_was => old_value 
  

因此，在before_create的before_update中，你应该有那些（你只能在保存之前检查！

收集所有这些方法的非常好的地方是在 Observer-class TicketObserver，因此您可以将观察者代码与实际模型分开。

例如

  class TicketObserver< ActiveRecord :: Observer 
 def before_update 
 ..在这里做一些检查.. 
 end 
 end 
  

启用观察者类，您需要将它添加到 environment.rb ：

  config.active_record.observers =：ticket_observer 
  

这应该让你开始：）

关联的评论。如果您这样做：

  new_comment = ticket.ticket_comments.build 
 new_comment.new_record？ => true 
 ticket.comments.changed => true 
  

这样就是你所需要的。这不适合你吗？
再次注意：你需要在保存之前检查这一点，当然是：）

我想你必须收集在before_create中改变的数据， before_update，并在after_update / create实际发送邮件（因为那样你肯定成功了）。

显然还不清楚。我会让它更清楚一点。我建议使用TicketObserver类。但是如果你想使用回调，它将是这样：

  class Ticked 
 
 before_save ：check_state 
 after_save：send_mail_if_needed 
 
 def check_state 
 @ logmsg =
如果ticket_comments.changed 
＃查找注释
 ticket_comments。每个| c | 
 @logmsg<< comment changedif c.changed？ 
 @logmsg<< comment addedif c.new_record？ 
 end 
 end 
 end 
 
 end 
 def send_mail_if_needed 
 if @ logmsg.size> 0 
 ..发送邮件.. 
 end 
 end 
  

I have two models Ticket and TicketComment, the TicketComment is a child of Ticket.

ticket.rb

class Ticket < ActiveRecord::Base
  has_many :ticket_comments, :dependent => :destroy, :order => 'created_at DESC'

  # allow the ticket comments to be created from within a ticket form
  accepts_nested_attributes_for :ticket_comments, :reject_if => proc { |attributes| attributes['comment'].blank? }
end

ticket_comment.rb

class TicketComment < ActiveRecord::Base
  belongs_to :ticket

  validates_presence_of :comment
end

What I want to do is mimic the functionality in Trac, where if a user makes a change to the ticket, and/or adds a comment, an email is sent to the people assigned to the ticket.

I want to use an after_update or after_save callback, so that I know the information was all saved before I send out emails.

How can I detect changes to the model (ticket.changes) as well as whether a new comment was created or not (ticket.comments) and send this update (x changes to y, user added comment 'text') in ONE email in a callback method?

解决方案

you could use the ActiveRecord::Dirty module, which allows you to track unsaved changes.

E.g.

t1 = Ticket.first
t1.some_attribute = some_new_value
t1.changed? => true
t1.some_attribute_changed? => true
t1.some_attribute_was => old_value 

So inside a before_update of before_create you should those (you can only check before the save!).

A very nice place to gather all these methods is in a Observer-class TicketObserver, so you can seperate your "observer"-code from your actual model.

E.g.

class TicketObserver < ActiveRecord::Observer
  def before_update
    .. do some checking here ..
  end
end

to enable the observer-class, you need to add this in your environment.rb:

config.active_record.observers = :ticket_observer

This should get you started :)

What concerns the linked comments. If you do this:

new_comment = ticket.ticket_comments.build
new_comment.new_record? => true
ticket.comments.changed => true

So that would be exactly what you would need. Does that not work for you? Note again: you need to check this before saving, of course :)

I imagine that you have to collect the data that has changed in a before_create or before_update, and in an after_update/create actually send the mail (because then you are sure it succeeded).

Apparently it still is not clear. I will make it a bit more explicit. I would recommend using the TicketObserver class. But if you want to use the callback, it would be like this:

class Ticked

  before_save :check_state
  after_save :send_mail_if_needed

  def check_state
    @logmsg=""
    if ticket_comments.changed
      # find the comment
      ticket_comments.each do |c| 
        @logmsg << "comment changed" if c.changed?
        @logmsg << "comment added" if c.new_record? 
      end
    end
  end

end
def send_mail_if_needed
  if @logmsg.size > 0
    ..send mail..
  end
end

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