javascript - belongsTo 使用 associate 似乎不起作用

Question

我的应用程序中有两个“模型”，它们分支到不同的文件中:

ApplicationSession.model.js

module.exports = function(sequelize, DataTypes) {

    const { INTEGER, DATE } = DataTypes;

    var ApplicationSession = sequelize.define("applicationSession", {
        sessionStart: DATE,
        sessionEnd: DATE
    }, {
        associate: (models) => {
            ApplicationSession.belongsTo(models.User, {
                foreignKey: 'userId',
                as: 'User',
            });
        }
    });

    return ApplicationSession;
};

用户模型.js

module.exports = function(sequelize, DataTypes) {

    const { STRING, INTEGER, DATE } = DataTypes;

    var User = sequelize.define("user", {
        name: STRING
    }, {
        associate: (models) => {
            User.hasMany(models.ApplicationSession);
        }
    });

    return User;
};

保存表格时(删除/重新创建) force: true和手动删除只是为了理智，从来没有为用户创建一个字段。

这是我加载不同模型的方式

import fs from 'fs';
import path from 'path';
import sequelize from '../connection';
var exports = {};

fs.readdirSync(__dirname).forEach(fileName => {
    if(~fileName.indexOf('.model.js')) {
        const subname = fileName.replace('.model.js', '');

        const model = sequelize.import(path.join(__dirname, fileName));
        exports[subname] = model;
    }

});

export default exports;

当所有模型都在一个文件中声明时，我可以使用 X.belongsTo(Y)没有任何问题，所以我想尝试将其添加到我的 sequelize.import 的底部来电

    exports['ApplicationSession'].belongsTo(exports['User'], { as: 'User', foreignKey: 'userId' });
    exports['User'].hasMany(exports['ApplicationSession']);

但是，这产生了一个不同的错误:

/node_modules/sequelize/lib/associations/mixin.js:96
      throw new Error(this.name + '.' + Utils.lowercaseFirst(Type.toString()) + ' called with something that\'s not an instance of Sequelize.Model');
      ^

Error: applicationSession.function BelongsTo(source, target, options) 

我该怎么做才能让人际关系发挥作用？

Answer 1

您需要在模型加载模块中再添加一件事以使关联起作用。

fs.readdirSync(__dirname).forEach(fileName => {
    if(~fileName.indexOf('.model.js')) {
        const subname = fileName.replace('.model.js', '');
        const model = sequelize.import(path.join(__dirname, fileName));
        exports[subname] = model;
    }
});

// You need to check for every model if it has `associate` class method
// and execute it
Object.keys(exports).forEach(function(modelName) {
  if ("associate" in exports[modelName]) {
    exports[modelName].associate(db);
  }
});

我还在您的代码中看到了另一个错误。模型中定义的类方法 associate应该环绕 classMethods属性(property)。

它应该是这样的:

var ApplicationSession = sequelize.define("applicationSession", {
    sessionStart: DATE,
    sessionEnd: DATE
}, {
    // Add this 
    classMethods: {
        associate: (models) => {   
            ApplicationSession.belongsTo(models.User, {
                foreignKey: 'userId',
                as: 'User',
            });
        }
    }
});

您可以按照 GitHub 中的示例进行后续处理.