Ruby-on-rails 在数据库中存储数组：JSON 与序列化数组
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Storing arrays in database : JSON vs. serialized array
提问by titibouboul
With ruby-on-rails, I want to store an array of 3 elements: the last 3 comments of a post. I know I could join the Comment table to the Post one, but I would avoid to do this heavy request for scaling purposes.
使用 ruby-on-rails，我想存储 3 个元素的数组：帖子的最后 3 条评论。我知道我可以将 Comment 表加入到 Post 表中，但我会避免为了缩放目的而执行这个繁重的请求。
So I was wondering what was the best way to store those 3 elements, as I would like to update them easily every time a new comment is made: remove the last comment and add the new one.
所以我想知道存储这 3 个元素的最佳方式是什么，因为我想在每次发表新评论时轻松更新它们：删除最后一条评论并添加新评论。
What is the correct way to do this ? Store it in a serialized array or in a JSON object ?
这样做的正确方法是什么？将其存储在序列化数组或 JSON 对象中？
回答by DiegoSalazar
You can store Arrays and Hashes using ActiveRecord's serializedeclaration:
您可以使用 ActiveRecord 的serialize声明来存储数组和哈希：
class Comment < ActiveRecord::Base
serialize :stuff
end
comment = Comment.new # stuff: nil
comment.stuff = ['some', 'stuff', 'as array']
comment.save
comment.stuff # => ['some', 'stuff', 'as array']
You can specify the class name that the object type should equal to (in this case Array). This is more explicit and a bit safer. You also won't have to create the array when you assign the first value, since you'll be able to append to the existing (empty) array.
您可以指定对象类型应等于的类名（在本例中为Array）。这更明确，也更安全。您也不必在分配第一个值时创建数组，因为您将能够附加到现有（空）数组。
class Comment < ActiveRecord::Base
serialize :stuff, Array
end
comment = Comment.new # stuff: []
comment.stuff << 'some' << 'stuff' << 'as array'
You can even use a neater version called store: http://api.rubyonrails.org/classes/ActiveRecord/Store.html
您甚至可以使用更简洁的版本 store：http: //api.rubyonrails.org/classes/ActiveRecord/Store.html
This should handle your use case using a built in method.
这应该使用内置方法处理您的用例。
