Ruby on Rails：如何使用 ActiveRecord 对两列进行排序？
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Ruby on Rails: how do I sort with two columns using ActiveRecord?
提问by NullVoxPopuli
I want to sort by two columns, one is a DateTime (updated_at), and the other is a Decimal (Price)
我想按两列排序，一列是日期时间（updated_at），另一列是十进制（价格）
I would like to be able to sort first by updated_at, then, if multiple items occur on the same day, sort by Price.
我希望能够首先按updated_at 排序，然后，如果同一天出现多个项目，则按价格排序。
采纳答案by Daniel Vandersluis
Assuming you're using MySQL,
假设您使用的是 MySQL，
Model.all(:order => 'DATE(updated_at), price')
Note the distinction from the other answers. The updated_atcolumn will be a full timestamp, so if you want to sort based on the dayit was updated, you need to use a function to get just the date part from the timestamp. In MySQL, that is DATE().
注意与其他答案的区别。该updated_at列将是一个完整的时间戳，因此如果您想根据更新日期进行排序，您需要使用一个函数从时间戳中获取日期部分。在 MySQL 中，即DATE().
回答by Christian Fazzini
In Rails 4 you can do something similar to:
在 Rails 4 中，您可以执行以下操作：
Model.order(foo: :asc, bar: :desc)
fooand barare columns in the db.
foo并且bar是数据库中的列。
回答by Erik Escobedo
回答by golfadas
Active Record Query Interfacelets you specify as many attributes as you want to orderyour query:
Active Record Query Interface允许您指定任意数量的属性来对查询进行排序：
models = Model.order(:date, :hour, price: :desc)
or if you want to get more specific (thanks @zw963):
或者如果您想获得更具体的信息（感谢@zw963）：
models = Model.order(price: :desc, date: :desc, price: :asc)
Bonus: After the first query, you can chain other queries:
奖励：在第一次查询之后，您可以链接其他查询：
models = models.where('date >= :date', date: Time.current.to_date)
回答by Ruby Racer
Actually there are many ways to do it using Active Record. One that has not been mentioned above would be (in various formats, all valid):
实际上，使用 Active Record 有很多方法可以做到这一点。上面没有提到的一个是（各种格式，都有效）：
Model.order(foo: :asc).order(:bar => :desc).order(:etc)
Maybe it's more verbose, but personally I find it easier to manage. SQL gets produced in one step only:
也许它更冗长，但我个人觉得它更容易管理。SQL 只需一步生成：
SELECT "models".* FROM "models" ORDER BY "models"."etc" ASC, "models"."bar" DESC, "models"."foo" ASC
Thusly, for the original question:
因此，对于原始问题：
Model.order(:updated_at).order(:price)
You need not declare data type, ActiveRecord does this smoothly, and so does your DB Engine
您不需要声明数据类型，ActiveRecord 可以顺利完成此操作，您的数据库引擎也是如此
回答by robertokl
Model.all(:order => 'updated_at, price')
回答by Max Alexander Hanna
None of these worked for me! After exactly 2 days of looking top and bottom over the internet, I found a solution!!
这些都不适合我！经过整整 2 天在互联网上查看顶部和底部，我找到了一个解决方案！！
lets say you have many columns in the products table including: special_price and msrp. These are the two columns we are trying to sort with.
假设您在产品表中有许多列，包括：special_price 和 msrp。这是我们尝试排序的两列。
Okay, First in your Model add this line:
好的，首先在您的模型中添加以下行：
named_scope :sorted_by_special_price_asc_msrp_asc, { :order => 'special_price asc,msrp asc' }
Second, in the Product Controller, add where you need to perform the search:
其次，在 Product Controller 中，添加您需要执行搜索的位置：
@search = Product.sorted_by_special_price_asc_msrp_asc.search(search_params)
