Rails:如何对多对多关系进行排序 [英] Rails: How to sort many-to-many relation

问题描述

我在模型用户和图片之间存在多对多关系.这些通过称为Picturization的联接表链接.

I have a many-to-many relationship between a model User and Picture. These are linked by a join table called Picturization.

如果我获得单个图片的用户列表，即picture.users->如何确保通过创建Picturization行(即，图片与图片关联的顺序)对获得的结果进行排序用户).如果我想按修改顺序获得此更改，该如何更改?

If I obtain a list of users of a single picture, i.e. picture.users -> how can I ensure that the result obtained is sorted by either creation of the Picturization row (i.e. the order at which a picture was associated to a user). How would this change if I wanted to obtain this in order of modification?

谢谢！

修改 也许像

picture.users.where(:order => "created_at")

• 但是这个created_at指的是图片中的created_at

推荐答案

在图形化表中还增加了一个列，例如 sequence ，并将排序顺序定义为Picturization中的默认范围

Have an additional column something like sequence in picturization table and define sort order as default scope in your Picturization

default_scope :order => 'sequence ASC'

如果您要基于Modify_at的默认排序顺序，请使用以下默认范围

If you want default sort order based on modified_at then use following default scope

default_scope :order => 'modified_at DESC'

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