Rails has_many，仅查找那些有孩子的人 [英] Rails has_many, find only those with children

问题描述

我的产品表has_many：registered_products。

My "products" table has_many :registered_products.

我想使用

products.find(:has_registered_products) 

其中仅返回产品在registered_products表中也有一个条目。我该如何实现？

where that will return only the products that also have an entry in the registered_products table. How could I achieve this?

推荐答案

只要您在registered_products表中具有该产品的外键，就可以执行以下操作：

As long as you have a foreign_key for the product in the registered_products table you can do:

has_many :registered_products
named_scope :with_registered_products, :joins => :registered_products

# if you're using rails 3
scope :with_registered_products, joins(:registered_products)

，并且只会返回至少具有一个相关注册产品的产品。

and that will only return products that have at least one associated registered product.

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