app.model.Classes.hasMany找不到属性，该引用的也引用了

Question

'use strict';

module.exports = app => {
    const { STRING, INTEGER, BOOLEAN } = app.Sequelize;

    const Classes = app.model.define('classes', {
        id: {
            type: INTEGER,
            autoIncrement: true,
            primaryKey: true
        },
        name: {
            type: STRING(50),
            allowNull: false,
        },
        age: {
            type: INTEGER,
            allowNull: false
        },
        sex: {
            type: BOOLEAN,
            allowNull: false,
            get() {
                if ( this.getDataValue('sex') ){
                    return '男';
                }else {
                    return '女';
                }
            }
        },
        studentId: {
            type: INTEGER,
            allowNull: false
        }
    });

    Classes.associate = function (){
        app.model.Classes.hasMany(app.model.Student, {foreignKey: 'classId', targetKey: 'id'});
    }

    return Classes;
}

E:\webServer1\app\model\oms\classes.js:38
        app.model.Classes.hasMany(app.model.Student, {foreignKey: 'classId', targetKey: 'id'});
                          ^

TypeError: Cannot read property 'hasMany' of undefined
    at Function.Classes.associate (E:\webServer1\app\model\oms\classes.js:38:27)
    at E:\webServer1\node_modules\egg-sequelize\lib\loader.js:118:54
    at Array.forEach (<anonymous>)
    at loadDatabase (E:\webServer1\node_modules\egg-sequelize\lib\loader.js:117:12)
    at module.exports (E:\webServer1\node_modules\egg-sequelize\lib\loader.js:32:20)
    at module.exports (E:\webServer1\node_modules\egg-sequelize\agent.js:4:26)
    at Hook.configDidLoad (E:\webServer1\node_modules\egg-core\lib\lifecycle.js:91:9)
    at Lifecycle.triggerConfigDidLoad (E:\webServer1\node_modules\egg-core\lib\lifecycle.js:145:14)
    at Lifecycle.triggerConfigWillLoad (E:\webServer1\node_modules\egg-core\lib\lifecycle.js:139:10)
    at AgentWorkerLoader.loadCustomAgent (E:\webServer1\node_modules\egg-core\lib\loader\mixin\custom.js:45:20)
    at AgentWorkerLoader.load (E:\webServer1\node_modules\egg\lib\loader\agent_worker_loader.js:23:10)
    at new Agent (E:\webServer1\node_modules\egg\lib\agent.js:24:17)
    at Object.<anonymous> (E:\webServer1\node_modules\egg-cluster\lib\agent_worker.js:28:15)
    at Module._compile (internal/modules/cjs/loader.js:1156:30)
    at Object.Module._extensions..js (internal/modules/cjs/loader.js:1176:10)
    at Module.load (internal/modules/cjs/loader.js:1000:32)
    at Function.Module._load (internal/modules/cjs/loader.js:899:14)
    at Function.executeUserEntryPoint [as runMain] (internal/modules/run_main.js:74:12)
    at internal/main/run_main_module.js:18:47
2020-04-25 15:55:36,716 ERROR 5992 nodejs.AgentWorkerDiedError: [master] agent_worker#1:18692 died (code: 1, signal: null)
    at Master.onAgentExit (E:\webServer1\node_modules\egg-cluster\lib\master.js:425:17)
    at Master.emit (events.js:310:20)
    at Messenger.sendToMaster (E:\webServer1\node_modules\egg-cluster\lib\utils\messenger.js:137:17)
    at Messenger.send (E:\webServer1\node_modules\egg-cluster\lib\utils\messenger.js:102:12)
    at ChildProcess.<anonymous> (E:\webServer1\node_modules\egg-cluster\lib\master.js:289:22)
    at Object.onceWrapper (events.js:417:26)
    at ChildProcess.emit (events.js:310:20)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:275:12)
name: "AgentWorkerDiedError"
pid: 5992
hostname: DESKTOP-GA8G421

2020-04-25 15:55:36,725 ERROR 5992 [master] agent_worker#1:18692 start fail, exiting with code:1
2020-04-25 15:55:36,751 ERROR 5992 [master] exit with code:1
Error: E:\webServer1\node_modules\egg-bin\lib\start-cluster {"typescript":false,"declarations":true,"workers":1,"baseDir":"E:\\webServer1","framework":"E:\\webServer1\\node_modules\\egg"} exit with code 1
    at ChildProcess.<anonymous> (E:\webServer1\node_modules\common-bin\lib\helper.js:56:21)
    at Object.onceWrapper (events.js:417:26)
    at ChildProcess.emit (events.js:310:20)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:275:12) {
  code: 1
}
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! ruiji_server@1.0.0 dev: `egg-bin dev`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the ruiji_server@1.0.0 dev script.
    at ChildProcess.emit (events.js:310:20)
    at Process.ChildProcess._handle.onexit (internal/child_process.js:275:12) {
  code: 1
}
npm ERR! code ELIFECYCLE
npm ERR! errno 1
npm ERR! ruiji_server@1.0.0 dev: `egg-bin dev`
npm ERR! Exit status 1
npm ERR!
npm ERR! Failed at the ruiji_server@1.0.0 dev script.
npm ERR! This is probably not a problem with npm. There is likely additional logging output above.

npm ERR! A complete log of this run can be found in:

Answer 1

1. 你这个应该是用egg-sequelize
2. 不需要写app.model，直接去掉

Classes.associate = function (){
        Classes.hasMany(app.model.Student, {foreignKey: 'classId', targetKey: 'id'});
    }