在哈希中保存错误排序后的 activerecord-postgres-hstore

问题描述

用Hstore存储为Hash Table，保存后Hash排序错误

class Service < ActiveRecord::Base
  serialize :properties, ActiveRecord::Coders::Hstore
end

service = Service.new
service.properties = { "aaa" => 1, "zz" => 2, "cc" => 3, "d" => 4 }
#=> { "aaa" => 1, "zz" => 2, "cc" => 3, "d" => 4 }
service.save
reload!
service = Service.find(:id)
service.properties
#=> { "d" => "4", "cc" => "3", "zz" => 2, "aaa" => 1 }
Bug::: wrong ordering after save

是不是因为序列化后按Tree排序.任何想法或任何人之前都遇到过这个问题?提前致谢.

Is it because after serialize that it orders by Tree. Any ideas or anyone had faced this problem before? Thanks in advance.

推荐答案

来自 精美的 PostgreSQL 手册:

F.16.hstore
[...]
该模块实现了 hstore 数据类型，用于在单个 PostgreSQL 值中存储键/值对集.
[...]
对的顺序并不重要(并且可能不会在输出中重现).

所以 PostgreSQL 的 hstore 类型是一组无序的键/值对，不保证键/值对的任何特定顺序.一旦您的 Ruby Hash 转换为 hstore，排序就会丢失.

So PostgreSQL's hstore type is an unordered set of key/value pairs that doesn't guarantee any particular order of the key/value pairs. Once your Ruby Hash is converted to an hstore, the ordering is lost.

如果您需要维护哈希中的顺序，则必须使用不同的序列化格式.

If you need to maintain the order in your Hash you'll have to use a different serialize format.

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