从其json表示中获取IPAddr实例 [英] Get IPAddr instance from its json representation

问题描述

$ p

上下文：

我正在使用使用 draftsman gem的Rails应用程序。基本上，当对数据库中的记录进行更改时，并且红宝石模型 has_drafts ，而不是立即更改记录，更改草案和生成的记录保存在草稿表中，直到一个发布！。然后对实际记录进行更改。相当整齐：）

草稿表包含允许在postgres表中的json列中进行更改的对象。

我也在使用Devise，我的用户模型使用可追踪模块，其中包含一个 current_sign_in_ip 以及列类型 inet 的 last_sign_in_ip 。

问题：

inet 在我的用户表中键入列，以及其余的用户对象，正在存储在由 draftsman gem创建的草稿表中，单个json列中名为物体。在这种情况下，由于以下原因： reify 该对象不成功，因为以下原因： IPAddr 实例有一个json表示 IPAddr 类不能察觉。例如，ruby中的 IPAddr 实例响应 to_json ，这给我看起来像这样： \ family\ ：2，\ addr\ ：2130706433，\ mask_addr\ ：4294967295}。这些实例也响应 to_s ，并给我这样的东西：127.0.0.1。不幸的是， IPAddr 类似乎不知道如何把自己从json从我可以告诉的东西：

< pre class =lang-rb prettyprint-override> [277,286] in /home/jake/.rvm/gems/ruby-2.2.1/bundler/gems/draftsman-1bd3c797d540/lib/ draftsman / model.rb
277：data = {
278：：item => self，
279：：whodunnit => Draftsman.whodunnit，
280：：object => object_attrs_for_draft_record
281：}
=> 282：data = merge_metadata_for_draft（data）
283：
284：＃如果已经有草稿，请更新。
285：if send（self.class.draft_association_name）.present？
286：data [：object_changes] = changes_for_draftsman如果track_object_changes_for_draft？

（byebug）data [：object] ['current_sign_in_ip']
＃< IPAddr：IPv4：127.0.0.1/255.255.255.255>
（byebug）data [：object] ['current_sign_in_ip']。to_json
{\family\：2，\add​​r\：2130706433，\mask_addr\\ \\：4294967295}

（byebug）IPAddr.new（data [：object] ['current_sign_in_ip']。to_s）
＃< IPAddr：IPv4：127.0.0.1/255.255 .255.255>
（byebug）IPAddr.new（data [：object] ['current_sign_in_ip']。to_json）
*** IPAddr :: InvalidAddressError异常：无效地址

nil
（byebug）


我想把这个问题发布给StackOverflow会引起这个问题的一些注意，我还在 Draftsman 问题 $ c> github页面，如果需要任何其他信息。

解决方案

不知道这是否有帮助，但如果您阅读我的评论d_ethier的答案您可以看到， IPAddr 并不知道有关JSON的任何内容。

但是，您可以将猴子修补要理解这样的JSON：

  require'active_model'
 require'active_support'
 require'active_support / core_ext'
 require'ipaddr'
 
 class IPAddr 
 include ActiveModel :: Serializers :: JSON 
 
 attr_accessor：addr，：mask_addr，：family 
 
 def attributes =（hash）
 hash.each do | key，value | 
 send（＃{key} =，value）
 end 
 end 
 
定义属性
 instance_values 
 end 
 end 
 
pi = IPAddr.new（'127.0.0.1'）
pj = i.to_json 
p IPAddr.new.from_json（j）
  

输出：

 ＃< IPAddr： IPv4的：127.0.0.1/255.255.255.255> 
{\family\：2，\add​​r\：2130706433，\mask_addr\：4294967295}
＃< IPAddr：IPv4：127.0。 0.1 / 255.255.255.255> 
  

资料来源：

http://apidock.com/rails/ActiveModel/Serializers/JSON/from_json

How can I get back an IPAddr instance from its json representation?

Context:

I'm working on a Rails application that uses the draftsman gem. Essentially, when one makes a change to a record in the database and that ruby model has_drafts, instead of making the change to the record right away, a draft of the changes and the resulting record is saved in the drafts table until one publish!es that draft. Then the changes are made to the actual record. Pretty neat :)

The drafts table holds the object that would result from allowing the changes to happen in a json column in a postgres table.

I'm also using Devise and my user model uses the trackable module, which includes a current_sign_in_ip as well as a last_sign_in_ip of column type inet.

Problem:

inet type columns in my user table, as well as the rest of the User object, are being stored in the drafts table created by the draftsman gem in a single json column called object. reifying the object from its draft does not succeed in this case because of the following reason: IPAddr instances have a json representation that the IPAddr class is incapable of perceiving. For example, IPAddr instances in ruby respond to to_json, which gives me something that looks like this: "\"family\":2,\"addr\":2130706433,\"mask_addr\":4294967295}". These instances also respond to to_s and give me something like this: "127.0.0.1". Unfortunately, the IPAddr class doesn't seem to know how to bring itself back from json from what I can tell:

[277, 286] in /home/jake/.rvm/gems/ruby-2.2.1/bundler/gems/draftsman-1bd3c797d540/lib/draftsman/model.rb
   277:               data = {
   278:                 :item      => self,
   279:                 :whodunnit => Draftsman.whodunnit,
   280:                 :object    => object_attrs_for_draft_record
   281:               }
=> 282:               data = merge_metadata_for_draft(data)
   283: 
   284:               # If there's already a draft, update it.
   285:               if send(self.class.draft_association_name).present?
   286:                 data[:object_changes] = changes_for_draftsman if track_object_changes_for_draft?

(byebug) data[:object]['current_sign_in_ip']
#<IPAddr: IPv4:127.0.0.1/255.255.255.255>
(byebug) data[:object]['current_sign_in_ip'].to_json
"{\"family\":2,\"addr\":2130706433,\"mask_addr\":4294967295}"

(byebug) IPAddr.new(data[:object]['current_sign_in_ip'].to_s)
#<IPAddr: IPv4:127.0.0.1/255.255.255.255>
(byebug) IPAddr.new(data[:object]['current_sign_in_ip'].to_json)
*** IPAddr::InvalidAddressError Exception: invalid address

nil
(byebug) 

I figured posting this question to StackOverflow would get some attention to this issue, but I also submitted a github issue on the Draftsman github page if any other information is needed.

解决方案

Not sure if this helps, but if you read my comment below d_ethier's answer you can see that IPAddr doesn't really know anything about JSON.

However you can monkey patch it to understand JSON like so:

require 'active_model'
require 'active_support'
require 'active_support/core_ext'
require 'ipaddr'

class IPAddr
  include ActiveModel::Serializers::JSON

  attr_accessor :addr, :mask_addr, :family

  def attributes=(hash)
    hash.each do |key, value|
      send("#{key}=", value)
    end
  end

  def attributes
    instance_values
  end
end   

p i = IPAddr.new('127.0.0.1')
p j = i.to_json
p IPAddr.new.from_json(j)

Output:

#<IPAddr: IPv4:127.0.0.1/255.255.255.255>
"{\"family\":2,\"addr\":2130706433,\"mask_addr\":4294967295}"
#<IPAddr: IPv4:127.0.0.1/255.255.255.255>

Source:
http://apidock.com/rails/ActiveModel/Serializers/JSON/from_json

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