Sequelize：TypeError：User.hasMany不是函數

Question

我有這種奇怪的行為。 我有一個用戶模型和一個客戶端模型。 用戶有很多客戶端。 我正在使用這個文檔： http ： //docs.sequelizejs.com/manual/tutorial/associations.html

當我運行服務器時，Sequelize拋出TypeError：User.hasMany不是一個函數

節點版本： 8.9.1
方言： postgres
數據庫版本： Postgres 10
Sequelize版本： 4.22.15

以下文件都在同一文件夾中

user.js模型

const Sequelize = require('sequelize');
const db = require('../index.js'); //This is an instance of new Sequelize(...)

const tableName = 'users';

const User = db.define('user', {
  firstName: {
    type: Sequelize.STRING(50),
    allowNull: false,
    validate: {
      notEmpty: true
    }
  },
  lastName: {
    type: Sequelize.STRING(50),
    allowNull: false,
    validate: {
      notEmpty: true
    }
  },
  username: { //Username will be the email
    type: Sequelize.STRING(80),
    allowNull: false,
    unique: true,
    validate: {
      isEmail: true
    }
  },
  password: {
    type: Sequelize.STRING,
    allowNull: false,
    validate: {
      notEmpty: true
    }
  },
  isAdmin: {
    type: Sequelize.BOOLEAN,
    allowNull: false,
    defaultValue: false
  },
  isActive: {
    type: Sequelize.BOOLEAN,
    allowNull: false,
    defaultValue: false
  }

}, { tableName });

module.exports = User;

client.js模型

'use strict'

const Sequelize = require('sequelize');
const db = require('../index.js');

const instanceMethods = {
  toJSON() {
    const values = Object.assign({}, this.get());

    return values;
  },
};

const Client = db.define('clients', {
  ibid: {
    type: Sequelize.BIGINT,
    allowNull: true,
    defaultValue: null
  },
  firstName: {
    type: Sequelize.STRING(50),
    allowNull: false,
    validate: {
      notEmpty: true
    }
  },
  lastName: {
    type: Sequelize.STRING(50),
    allowNull: false,
    validate: {
      notEmpty: true
    }
  },
  agreementSigned: {
    type: Sequelize.BOOLEAN,
    allowNull: false,
    defaultValue: false
  },
  totalBalance: {
    type: Sequelize.DECIMAL(11,2),
    allowNull: true,
    defaultValue: null
  },
  currentAllocation: {
    type: Sequelize.STRING,
    allowNull: true,
    defaultValue: null
  }

}, { instanceMethods });

module.exports = Client;

index.js模型

'use strict';

const User = require('./user')
const Client = require('./client');

User.hasMany(Client);
Client.belongsTo(User);

module.exports = {User, Client};

Answer 1

在index.js中，您尚未導出已初始化的新sequelize實例，因此client.js和user.js無法使用它！ define函數適用於您創建的sequelize實例對象！

此外，項目中存在循環依賴，這可能會產生問題！

我嘗試了你的代碼並改變了結構，它現在正常工作！ 可能還有其他結構，但這個對我有用！

1）不要在index.js中創建一個新的sequelize實例，而是創建另一個文件，作為sequelize實例的初始化！

sequelize_index.js（我使用此文件創建基本實例，然后在客戶端和用戶模型中使用此基本實例）

const Sequelize = require('sequelize');
const dbconfig=require('./dbconfig.json');

const sequelize = new Sequelize('postgres://' + dbconfig.USER + ":" +     dbconfig.PASSWORD + "@" + dbconfig.HOST + ":5432/" + dbconfig.DB, {
host: dbconfig.HOST,
dialect: dbconfig.DIALECT,
pool: {
    min: 0,
    max: 5,
    idle: 1000
     }
});

 module.exports={sequelize};

2）cli​​ent.js看起來像這樣！

'use strict'
const Sequelize = require('sequelize');

const sequelize=require('./sequelize_index').sequelize;
const db = require('./index.js');

const instanceMethods = {
    toJSON() {
        const values = Object.assign({}, this.get());

        return values;
    },
};

const Client = sequelize.define('clients', {
    ibid: {
        type: Sequelize.BIGINT,
        allowNull: true,
        defaultValue: null
    },
    firstName: {
        type: Sequelize.STRING(50),
        allowNull: false,
        validate: {
            notEmpty: true
        }
    },
    lastName: {
        type: Sequelize.STRING(50),
        allowNull: false,
        validate: {
            notEmpty: true
        }
    },
    agreementSigned: {
        type: Sequelize.BOOLEAN,
        allowNull: false,
        defaultValue: false
    },
    totalBalance: {
        type: Sequelize.DECIMAL(11,2),
        allowNull: true,
        defaultValue: null
    },
    currentAllocation: {
        type: Sequelize.STRING,
        allowNull: true,
        defaultValue: null
    }

}, { instanceMethods });

module.exports = Client;

3）User.js

const Sequelize = require('sequelize');
const sequelize=require('./sequelize_index').sequelize;
const db = require('./index.js'); //This is an instance of new Sequelize(...)

const tableName = 'users';

const User = sequelize.define('user', {
    firstName: {
        type: Sequelize.STRING(50),
        allowNull: false,
        validate: {
            notEmpty: true
        }
    },
    lastName: {
        type: Sequelize.STRING(50),
        allowNull: false,
        validate: {
            notEmpty: true
        }
    },
    username: { //Username will be the email
        type: Sequelize.STRING(80),
        allowNull: false,
        unique: true,
        validate: {
            isEmail: true
        }
    },
    password: {
        type: Sequelize.STRING,
        allowNull: false,
        validate: {
            notEmpty: true
        }
    },
    isAdmin: {
        type: Sequelize.BOOLEAN,
        allowNull: false,
        defaultValue: false
    },
    isActive: {
        type: Sequelize.BOOLEAN,
        allowNull: false,
        defaultValue: false
    }

}, { tableName });

module.exports = User;

4）index.js

'use strict';
const sequelize = require('./sequelize_index').sequelize;
const User = require('./user')
const Client = require('./client');


User.hasMany(Client);
Client.belongsTo(User);

sequelize.sync({force: false}).then(function () {
    console.log("Database Configured");
});
module.exports = {User, Client};

運行index.js后，將創建數據庫！