Rails 4按虚拟属性排序 [英] Rails 4 order by virtual attribute

问题描述

我有一个产品模型，该模型具有名称和描述数据库中的列。

I have a Product model which has name and description columns in the database.

我也有一个 Product.search_results_for（query），其中 query 是类似于青苹果 的字符串。

I also have a Product.search_results_for(query), where query is a string like "Green Apple".

我需要返回效果最好的排序结果的 ActiveRecord :: Relation 。目前，我正在为每个产品设置 search_result_value 。 search_result_value 不是数据库中的一列，我也不希望这样。

I need to return an ActiveRecord::Relation of the results ordered by which is the best hit. Currently, I'm setting a search_result_value to each product. search_result_value IS NOT a column in the database, and I don't want it to be.

所以从本质上讲，我有一个产品的 ActiveRecord :: Relation ，我需要按 search_result_value 进行排序，而无需将其更改为数组，这是一个未存储在数据库中的实例变量。我该怎么做？

So in essence, I have an ActiveRecord::Relation of Products that I need to order by search_result_value without changing it to an array, which is an instance variable that isn't stored in the database. How can I do this?

类似这样的东西：

Product.order(:search_result_value)

推荐答案

如果您不输入列中的值或在纯SQL中的 search_result_value 中表达逻辑，则必须将所有产品加载到内存中，然后使用 sort_by ：

If you do not put the value in a column or express the logic in search_result_value in pure SQL, then you’ll have to load all Products into memory and then sort them in Ruby using sort_by:

Product.all.to_a.sort_by(&:search_result_value)

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