Ruby-on-rails 如何在rails中将数组保存到数据库
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how to save array to database in rails
提问by tardjo
if i have params like this :
如果我有这样的参数：
params["scholarship"] = {"name"=>"test", "state_ids"=>["1", "2", "3", "4"]}
and when i create object to database field state_id not save to database?
当我创建对象到数据库字段 state_id 时没有保存到数据库？
how to save to database with format :
如何以格式保存到数据库：
#<Scholarship id: 1, name: "test", state_id: "["1", "2", "3", "4"]">
how do that?
怎么办？
thanks before
之前谢谢
采纳答案by Rubyist
For example:
例如：
class User < ActiveRecord::Base
serialize :scholarship
end
user = User.create(:scholarship=> { "name" => "test", "state_ids" => ["1", "2"]})
User.find(user.id).scholarship# => { "name" => "test", "state_ids" => ["1", "2"] }
回答by cnnr
Also you can use PostrgreSQL support for array storing. (If you're using PG of course). Your migration will look like that:
您也可以使用 PostrgreSQL 支持数组存储。（当然，如果您使用的是 PG）。您的迁移将如下所示：
add_column :table_name, :column_name, :string, array: true, default: []
But don't forget about validations.
但不要忘记验证。
回答by j-dexx
回答by TomDunning
state_ids != state_id
you've got 2 different names for your attribute, so they don't line up.
then use serialize :state_idsonce you've renamed the column.
您的属性有 2 个不同的名称，因此它们不会对齐。然后serialize :state_ids在重命名列后使用。
However if you're storing a list of state_ids, i'm going to guess you also have a states table, and so should look into using has_and_belongs_to_manyassociation.
但是，如果您要存储 state_id 列表，我猜您还有一个状态表，因此应该考虑使用has_and_belongs_to_many关联。
