Firebase 简单的多对多关系 [英] Firebase simple many to many relationship

问题描述

我对 NoSQL 和 Firebase 实时数据库有点熟悉，而且我知道这不是解决关系数据库更合适的任务的最佳解决方案.我想验证我拥有的简单多对多关系的结构.

I am bit familiar with NoSQL and Firebase Realtime Database and also I know that it is not best solution to solve tasks where relational database should be more appropriate. I want to verify about structure of simple many to many relationship that I have.

我有事件和用户.我想使用 Firebase 存储有关用户参与活动的信息，稍后我需要

I have events and users. I want to use Firebase for storing information about users participating in events, later I will need to

• 获取活动用户列表，知道它的 id 和城市
• 获取用户活动列表，了解其 id 和城市
• 添加或删除有关用户参加活动的信息

• Get list of users for event knowing it's id and city
• Get list of events for users knowing it's id and city
• add or delete information about user attending to event

我想要按城市划分的第一个事件 ID 树.

I would like to have first tree of events ids divided by cities.

events {
'city1' : {
           event_id_1 : {'user_1', 'user_2'},
           event_id_2 : {'user_3', 'user_4'}. 
           }
'city2' : {
           event_id_3 : {'user_5', 'user_6'},
           event_id_4 : {'user_7', 'user_7'}. 
           }
}

用户的第二棵树

users {
'user1' : {
           'city1' : {event_id_1, event_id_2}, 
           'city2' : {event_id_3, event_id_4},
           'city3' : {event_id_3, event_id_4}
           }, 
'user2' : {
           'city1' : {event_id_1, event_id_2}, 
           'city2' : {event_id_3, event_id_4},
           'city3' : {event_id_3, event_id_4}
           },
'user3' : {
           'city1' : {event_id_1, event_id_2}, 
           'city2' : {event_id_3, event_id_4},
           'city3' : {event_id_3, event_id_4}
           },
}

是否易于使用和维护?

推荐答案

考虑到列出的要求，您的结构在我看来还不错.最重要的是:您已经在两个方向上存储数据，这对于许多刚接触 NoSQL 数据建模的开发人员来说是最大的障碍.

Your structure looks pretty OK to me given the requirements listed. Most importantly: you store the data in both directions already, which is the biggest hurdle for many developers new to NoSQL data modeling.

关于您的数据模型的一些注意事项，尽管大多数都属于拼写错误:

A few notes about your data model, though most are on the level of typos:

1. 务必将数据存储为地图，而不是数组.所以 event_id_1 : {'user_1': true, 'user_2': true }
2. 如果用户和事件之间存在多对多关系，我通常会有四个顶级列表:users 和 events(用于主要信息)，然后是 userEvents 和 eventUsers(用于两者之间的连接).

1. Be sure to store the data as maps, not arrays. So event_id_1 : {'user_1': true, 'user_2': true }
2. If there is a many-to-many relationship between users and events, I'd usually have four top-level lists: users and events (for the primary information about each), and then userEvents and eventUsers (for connections between the two).

将用户添加到事件可以通过单个多位置更新来完成，例如:

Adding a user to an event can be done with a single multi-location update, e.g.:

ref.update({
  '/userEvents/userId1/eventId1': true,
  '/eventUsers/eventId1/userId1': true
});

取消注册它们只需使用 null 作为值(删除现有键):

Unregistering them is a matter of doing the same with null as the value (which deletes the existing key):

ref.update({
  '/userEvents/userId1/eventId1': null,
  '/eventUsers/eventId1/userId1': null
});

还可以在这里查看我的答案:Firebase 中的多对多关系

Also see my answer here: Many to Many relationship in Firebase

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