为什么我不能在Rails的表中创建一个数组作为列？

Why can't I do something like this:

为什么我不能这样做：

class CreateModels < ActiveRecord::Migration
  def self.up
    create_table :fruit do |t|
      t.array :apples
    end
  end
end

Is there some other way to make an array ("apples) be an attribute of an instance of the Fruit class?

是否有其他方法可以使数组（“apples”）成为Fruit类实例的属性？

3 个解决方案

#1

Check out the Rails guide on associations (pay particular attention to has_many).

查看关于关联的Rails指南（特别注意has_many）。

You can use any column type supported by your database (use t.column instead of t.type), although if portability across DBs is a concern, I believe it's recommended to stick to the types explicitly supported by activerecord.

您可以使用数据库支持的任何列类型（使用t.column而不是t.type），但如果担心跨DB的可移植性，我相信建议坚持使用activerecord明确支持的类型。

It seems kind of funny for fruit to have_many apples, but maybe that is just an example? (I would expect apples to be a subclass of fruit).

拥抱苹果的水果似乎很有趣，但也许这仅仅是一个例子？（我希望苹果成为水果的子类）。

#2

In Rails 4 and using PostgreSQL you can actually use an array type in the DB:

在Rails 4中并使用PostgreSQL，您实际上可以在DB中使用数组类型：

Migration:

移民：

class CreateSomething < ActiveRecord::Migration
  def change
    create_table :something do |t|
      t.string :some_array, array: true, default: []
      t.timestamps
    end
  end
end

#3

You may use serialize. But if an Apple is going to be an AR object, use associations.

您可以使用序列化。但如果Apple将成为AR对象，请使用关联。

#1