MongoDB 多对多关联 [英] MongoDB Many-to-Many Association

问题描述

您将如何与 MongoDB 进行多对多关联?

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

例如；假设您有一个用户表和一个角色表.用户有很多角色，角色有很多用户.在 SQL 域中，您将创建一个 UserRoles 表.

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

在 MongoDB 中如何处理同类关系?

How is same sort of relationship handled in MongoDB?

推荐答案

根据您的查询需求，您可以将所有内容放入用户文档中:

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

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

要获得所有工程师，请使用:

To get all the Engineers, use:

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

如果您想在单独的文档中维护角色，那么您可以在角色数组中包含文档的 _id 而不是名称:

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"]
}

并设置如下角色:

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

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