如何在Ruby on Rails中将数组持久化到数据库？ [英] How can I persist an array to the database in Ruby on Rails?

问题描述

现在，我有一个可以容纳这样一个数组的对象，并且实例看起来保存没有问题。然而，它显然不是被持久化到数据库 - 当我调用My_Object.array中的函数的视图不同于数组被创建的视图，它出来nil，不工作。

例如：

  class My_Object< ActiveRecord :: Base 
 attr_accessor：array 
 end 
  

c $ c> My_Object.new（：array => [[1，2，3]，[4,5,6]]），一切似乎工作正常，在任何地方访问：array 属性，它只会变成nil。

任何想法？

解决方案

首先在表中创建一个名为 array 的文本列。然后使用 serialize ：

  class My_Object< ActiveRecord :: Base 
 serialize：array 
 end 
  

数组使用YAML，并且当你将它从数据库中取出时自动解包。

你应该重新考虑你的设计。您将无法对数据库中的序列化数据执行任何操作，特别是，您将无法在查询中使用它。 YAML将只是一个不透明的blob进入数据库并回来，数据库将无法做任何其他与它。如果你确定数据库永远不需要在数组里面，然后使用 serialize ，否则你将需要设置额外的表来存储您的数组数据。

I'm trying to persist an Array of Arrays to my SQLite database in Rails.

Right now, I've got an object that can hold such an Array, and instances appear to save with no problem. However, it's clearly not being persisted to the database-- when I call functions on My_Object.array in views different than the one that the array is created on, it comes out nil and doesn't work.

For example:

class My_Object < ActiveRecord::Base
  attr_accessor :array
end

When I call My_Object.new(:array => [ [1, 2, 3], [4, 5, 6] ]), everything appears to work properly, but I can't access the :array property anywhere else, it just turns out nil.

Any ideas?

解决方案

First create a text column called array in your table. Then use serialize:

class My_Object < ActiveRecord::Base
  serialize :array
end

That will automatically serialize your array using YAML and automatically unpack it when you pull it back out of the database.

You should reconsider your design though. You won't be able to do anything at all with the serialized data inside the database and in particular, you won't be able to use it in queries. The YAML will be just an opaque blob that goes into the database and comes back out, the database won't be able to do anything else with it. If you're certain that the database will never need to look inside array then go ahead and use serialize, otherwise you'll want to set up extra tables to store your array data.

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