ActiveRecord和ActiveRecord :: Relation对象之间的区别 [英] Difference between ActiveRecord and ActiveRecord::Relation objects

问题描述

我已经搜索了但找不到ActiveRecord和ActiveRecord :: relation对象之间的区别的简要说明。

I have searched but not able to find the brief explanation for the difference between ActiveRecord and ActiveRecord::relation object.

我了解ActiveRecord是单个对象通过类似的方式查找

I have understand that ActiveRecord is the single object find by something like

User.find(1)

和ActiveRecord :: Relation是类似对象的数组，查找对象的方式类似于

And ActiveRecord::Relation is the array like object Find by something like

User.where(id: 1)

我正在寻找查询之间的区别执行或对其进行深入的解释，因此将清除其背后的整个概念。

I am looking for the difference between them in terms of query execution or deep explanation about them, so it will clear the whole concept behind it.

预先感谢！

推荐答案

ActiveRecord :: Base 的实例是一个对象，代表数据库的特定行（或可能保存到数据库中） ）。

An instance of ActiveRecord::Base is an object that represents a specific row of your database (or might be saved into the database).

而 ActiveRecord :: Relation 的实例表示可以针对您的查询运行的查询数据库（但不是运行）。通过调用 to_a ，每个每个，第一个等。在该 Relation 实例中，将返回一个实例或 ActiveRecord :: Base 实例的数组。

Whereas an instance of ActiveRecord::Relation is a representation of a query that can be run against your database (but wasn't run yet). Once you run that query by calling to_a, each, first etc. on that Relation a single instance or an array of ActiveRecord::Base instances will be returned.

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