Sequelize Find belongsToMany 关联

Posted 2023-03-07

【中文标题】Sequelize Find belongsToMany 关联

【英文标题】：Sequelize Find belongsToMany Association

【发布时间】：2017-08-15 00:08:00

【问题描述】：

我在两个表之间有一个关联 m:n 与这样的 sequelize：

课程

module.exports = function(sequelize, DataTypes) 

  var Course = sequelize.define('Course', 
     .....
    ,
    
      associate: function(models)
        Course.hasMany(models.Schedule);
        Course.belongsTo(models.Period);
        Course.belongsTo(models.Room);
        Course.belongsTo(models.Subject);
        Course.belongsTo(models.School);
        Course.belongsTo(models.Person,  as: 'Teacher' );
      
    
  );
 return Course;
;

人物

module.exports = function(sequelize, DataTypes) 

  var Person = sequelize.define('Person', 
    ....
    ,
    
      associate: function(models)
        Person.belongsTo(models.Role,  as: 'Role' );
        Person.belongsTo(models.School,  as: 'School' );
        Person.belongsTo(models.Person,  as: 'Tutor' );
      
    
  );

  return Person;
;

以及关联表Enrollment

module.exports = function(sequelize, DataTypes) 

  var Enrollment = sequelize.define('Enrollment', 
      ....
    ,
    
      associate: function(models)
        Enrollment.belongsTo(models.Product, as: 'Product');
        Enrollment.belongsTo(models.School,  as: 'School' );

        models.Person.belongsToMany(models.Course, through: model: Enrollment,foreignKey: 'StudentEnrollId');
        models.Course.belongsToMany(models.Person, through: model: Enrollment,foreignKey: 'CourseEnrollId');

      
    

  );
  return Enrollment;
;

我尝试关注这个“example”，但没有解释太多，而是一个简单的查询，其中包含参数。

我试图存档的是获取所有课程给定一个学生 ID（人模型）。如您所见，课程模型仅保存共同构成课程的不同表的 id。 Person 模型也与不同的模型相关联，因此我使用 foreignKey: 'StudentEnrollId' 提供自定义 id 名称，但是当我尝试在包含 model : db.Person, as: 'StundetEnroll' 中指定 id 名称时，查询显示以下错误：Person (StudentEnroll) is not associated to Course

【参考方案1】：

您还需要在belongsToMany 关联中定义别名as

models.Person.belongsToMany(models.Course,  as: 'CourseEnrolls', through:  model: Enrollment , foreignKey: 'StudentEnrollId');
models.Course.belongsToMany(models.Person,  as: 'StudentEnrolls', through:  model: Enrollment , foreignKey: 'CourseEnrollId');

现在您可以查询Course 及其所有学生，反之亦然

models.Course.findByPrimary(1, 
    include: [
        
            model: models.Person,
            as: 'StudentEnrolls'
        
    ]
).then(course => 
    // course.StudentEnrolls => array of Person instances (students of given course)
);

您还可以使用get/set Associations 方法来检索或设置关联对象

// assuming that course is an instance of Course model
course.getStudentEnrolls().then(students => 
    // here you get all students of given course
);

【讨论】：

谢谢，这对我帮助很大。现在我只需要使用包含来获取其他数据。