ruby-on-rails - 无法再序列化为ActiveSupport::HashWithIndifferentAccess

由于到目前为止我完全无法解读的原因，我不再能够使用ActiveSupport::HashWithIndifferentAccess。

模型的相关部分如下所示:

class Item < ActiveRecord::Base
  serialize :metadata, ActiveSupport::HashWithIndifferentAccess

(我添加了尝试将其强制执行的选项，但并没有帮助。以前，这一切都很好，并且在那儿我还没有。)

只要对象在内存中，一切就可以正常工作。正确地，它是一个HashWithIndifferentAccess，而且生活很好。将其保存到数据库后，将其另存为哈希:

mysql> select * from items;
+----+------+-------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------+
| id | link | text        | metadata                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                                            | category_id |
+----+------+-------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------+
|  1 | NULL | Apple Store | ---
id: 42cc7080f964a520e9251fe3
name: Apple Store
contact:
  phone: '4153920202'
  formattedPhone: [phone]
location:
  address: 1 Stockton St.
  crossStreet: at Ellis St.
  lat: '37.78573590563453'
  lng: '-122.40610713227913'
  distance: '1784'
  postalCode: '94108'
  city: San Francisco
  state: CA
  country: USA
categories:
  '0':
    id: 4bf58dd8d48988d122951735
    name: Electronics Store
    pluralName: Electronics Stores
    shortName: Electronics
    icon: https://foursquare.com/img/categories/shops/technology.png
    parents:
    - Shops & Services
    primary: 'true'
verified: 'false'
stats:
  checkinsCount: '30462'
  usersCount: '16105'
  tipCount: '128'
url: http://apple.com/sanfrancisco
hereNow:
  count: '7'
 | 1           |
+----+------+-------------+---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------+-------------+

这意味着它不能被强制返回到HashWithIndifferentAccess中，并且事情像这样爆炸:

ActiveRecord::SerializationTypeMismatch in Index#index

Showing /development/lists.io/website/app/views/users/_todo.html.haml where line #7 raised:

Attribute was supposed to be a ActiveSupport::HashWithIndifferentAccess, but was a Hash

这使用的是Rails 3.1.3，使用mysql2 gem版本0.3.10将数据存储在MySQL中。我也正在运行ruby 1.9.2p290。我可以添加任何人都认为有帮助的信息，但是对于如何进一步调试它，我一无所知。

最佳答案

1.9.2通常包括Psych作为YAML库。但是，libyaml是一个外部依赖关系，如果在编译Ruby时libyaml不可用，则1.9.2默认使用Syck(旧库):link

Psych YAML将ActiveSupport::HashWithIndifferentAccess用作标准哈希的事实是Psych的Github上的oustanding issue。似乎已在1.9.3中修复。