MongoDB的许多-to-many关联 [英] MongoDB Many-to-Many Association

问题描述

你会怎么做一个多到很多协会的MongoDB？

How would you do a many-to-many association with MongoDB?

例如;假设你有一个用户表和角色表。用户有很多角色和角色有许多用户。在SQL的土地，你将创建一个表的UserRole

For example; let's say you have a Users table and a Roles table. Users have many roles, and roles have many users. In SQL land you would create a UserRoles table.

Users:
    Id
    Name

Roles:
    Id
    Name

UserRoles:
    UserId
    RoleId

如何为同一类的关系在MongoDB中如何处理？

How is same sort of relationship handled in MongoDB?

推荐答案

根据您的查询需要，你可以把用户文档中的所有内容：

Depending on your query needs you can put everything in the user document:

{name:"Joe"
,roles:["Admin","User","Engineer"]
}

要得到所有的工程师使用：

To get all the Engineers, use:

db.things.find( { roles : "Engineer" } );

如果你想保持在单独的文档中的作用，那么你可以包括文档的角色数组，而不是名称_id：

If you want to maintain the roles in separate documents then you can include the document's _id in the roles array instead of the name:

{name:"Joe"
,roles:["4b5783300334000000000aa9","5783300334000000000aa943","6c6793300334001000000006"]
}

和建立的角色，如：

{_id:"6c6793300334001000000006"
,rolename:"Engineer"
}

这篇关于MongoDB的许多-to-many关联的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持IT屋！