Sequelize 多对多自引用

Posted 2023-03-07

【中文标题】Sequelize 多对多自引用

【英文标题】：Sequelize many-to-many self reference

【发布时间】：2015-04-06 22:53:48

【问题描述】：

我正在尝试从 sequelize 中获取关联 examples 之一，但它似乎没有正确设置连接表。在示例中，我们有一个名为 Person 的模型，然后是 Person 的子代的多对多自引用。代码：

var Sequelize = require('sequelize');
var sequelize = new Sequelize('postgres://root@localhost/database_bug');

var Person = sequelize.define('Person', 
  id: 
    type: Sequelize.INTEGER,
    primaryKey: true,
    autoIncrement: true
  ,
  name: 
    type: Sequelize.STRING,
    allowNull: false
  
);

Person.belongsToMany(Person,  as: 'Children', through: 'PersonChildren' );

Person.sequelize.sync(force:true).then(function() 
  Person.build( name: 'John Doe' ).save().then(function(father) 
    Person.build( name: 'Jane Doe' ).save().then(function(daughter) 
      father.addChild(daughter);
    );
  );
);

但是当我在 postgres 中查看我的表时，我觉得自动生成的连接表中缺少一列。

            List of relations
 Schema |      Name      |   Type   | Owner 
--------+----------------+----------+-------
 public | People         | table    | root
 public | People_id_seq  | sequence | root
 public | PersonChildren | table    | root

                                    Table "public.People"
  Column   |           Type           |                       Modifiers                       
-----------+--------------------------+-------------------------------------------------------
 id        | integer                  | not null default nextval('"People_id_seq"'::regclass)
 name      | character varying(255)   | not null
 createdAt | timestamp with time zone | not null
 updatedAt | timestamp with time zone | not null
Indexes:
    "People_pkey" PRIMARY KEY, btree (id)
Referenced by:
    TABLE ""PersonChildren"" CONSTRAINT "PersonChildren_PersonId_fkey" FOREIGN KEY ("PersonId") REFERENCES "People"(id)

          Table "public.PersonChildren"
  Column   |           Type           | Modifiers 
-----------+--------------------------+-----------
 createdAt | timestamp with time zone | not null
 updatedAt | timestamp with time zone | not null
 PersonId  | integer                  | not null
Indexes:
    "PersonChildren_pkey" PRIMARY KEY, btree ("PersonId")
Foreign-key constraints:
    "PersonChildren_PersonId_fkey" FOREIGN KEY ("PersonId") REFERENCES "People"(id)

PersonChildren 需要一个名为 ChildId 的列或类似的东西来将 Person 链接到它的 Child。

人员表：

database_bug=# SELECT * FROM "People";
 id |   name   |         createdAt          |         updatedAt          
----+----------+----------------------------+----------------------------
  1 | John Doe | 2015-02-06 09:36:44.975-08 | 2015-02-06 09:36:44.975-08
  2 | Jane Doe | 2015-02-06 09:36:44.985-08 | 2015-02-06 09:36:44.985-08

更奇怪的是，我选择确保将 daughter 作为子级添加到 father：

database_bug=# SELECT * from "PersonChildren";
         createdAt          |         updatedAt          | PersonId 
----------------------------+----------------------------+----------
 2015-02-06 09:36:44.997-08 | 2015-02-06 09:36:44.997-08 |        2

但 PersonId 是 2，而不是 1。father 应该添加 daughter，而不是相反。

任何想法如何让这个协会运作？

【参考方案1】：

好的，看起来文档中的示例是错误的。公平地说，他们确实说必须使用hasMany，但随后展示了一个使用belongsToMany 的示例。

我将belongsToMany 更改为hasMany，看起来我们很高兴：

          Table "public.PersonChildren"
  Column   |           Type           | Modifiers 
-----------+--------------------------+-----------
 createdAt | timestamp with time zone | not null
 updatedAt | timestamp with time zone | not null
 PersonId  | integer                  | not null
 ChildId   | integer                  | not null

database_bug=# select * from "PersonChildren";
         createdAt          |         updatedAt          | PersonId | ChildId 
----------------------------+----------------------------+----------+---------
 2015-02-06 10:04:21.624-08 | 2015-02-06 10:04:21.624-08 |        1 |       2

现在我可以执行father.getChildren() 并且promise 将返回一个孩子列表。

【讨论】：

此问题已在 Sequelize 中修复。他们现在建议您在创建多对多自引用时使用 .belongsToMany。

在创建多对多自引用时，有没有 belongsToMany 的例子？