NodeJS:如何实现存储库模式

时间:2018-05-29 19:57:46

标签: node.js repository-pattern

我想在我的NodeJS应用程序中实现Repository模式,但我遇到了循环要求的麻烦(我猜......)。

我是如何尝试实施它的:

  • PersonRepository类,包含方法:getAll,getById,create,update,delete
  • 具有方法的人员类:init,createAccount,showRelations,addRelation,

首先:我的存储库模式设计是否正确?

我的课程:

personRepository.js

const PersonModel = require('./model');
const Person = require('./person');

class PersonRepository {

    constructor() {
        this._persons = new Set();
    }

    getAll( cb ) { // To Do: convert to promise
        let results = new Set();

        PersonModel.find({}, 'firstName lastName', (err, people) => {
            if (err) { 
                console.error(err);
            }
            people.forEach((person, index) => {
                let foundPerson = new Person(person._id.toString(), person.firstName, person.lastName, person.email, person.birthday);
                results.add(foundPerson);
            });
            this._persons = results;
            if (cb) cb(this._persons);
        });
    }

    getById(id) {

        return PersonModel.findOne({ _id: id });

    }

    getByEmail(email) {
        throw new Error("Method not implemented");
    }

    create( person ) {
        throw new Error("Method not implemented");
    }

    update ( person ) {
        throw new Error("Method not implemented");
    }

    delete ( person ) {
        throw new Error("Method not implemented");
    }
}

module.exports = new PersonRepository();

person.js

const PersonModel = require('./model');
const personRepository = require('./personRepository');

class Person {

    constructor(personId, first, last, email, birthday) {
        this._id = personId ? personId : undefined;
        this._firstName = first ? first : undefined;
        this._lastName = last ? last : undefined;
        this._email = email ? email : undefined;
        this._birthday = birthday ? new Date(birthday) : undefined;
        this._relations = new Map();
    }
    init() { // Get all data from database
        personRepository.getById(this._id)
            .then(console.log)
            .catch(console.error);
    }

}

module.exports = Person;

tests.js

console.log("--- GET ALL : results--- ");
personRepository.getAll( (persons) => {
    for (let person of persons) {
        person.loadAllData()
            .then(() => {
                console.log(person);
            })
            .catch((e) => {
                console.log(e);
            });
    }

});
console.log("--- INIT : results--- ");
var personInit = new Person("59c18a9029ef510012312995");
console.log("before init");
console.log(personInit);
personInit.init();
console.log("after init");
console.log(personInit);

问题: 当运行"全部获取"测试(没有INIT测试),它的工作原理。 当我添加INIT测试时,我收到错误:

personRepository.getById(this._id)
                         ^

TypeError: personRepository.getById is not a function
    at Person.init

如何防止这种情况发生?   - 改变我需要模块的方式?   - 改变我的设计? (例如,不要在personRepository中使用Person类,只需在" getAll"而不是一组人中创建一组ID)   - 其他想法?

谢谢你的帮助!我现在试图解决这个问题几个小时......

1 个答案:

答案 0 :(得分:1)

自己解决了。问题是两个模块之间存在循环依赖关系。通过在require之后移动module.exports来解决问题。

参考:http://blog.cloudmineinc.com/managing-cyclic-dependencies-in-node.js?hsFormKey=ae1b2c3916d0a2be7aafb5d841ce24c0