koa --- > [MVC实现之五]Model层的实现

说明

• 上一篇: MVC实现之四
• 这一篇主要介绍:
  • 项目中用到的Sequelize库中的一些方法,参考使用Sequelize连接mysql
  • 将Model层加入Mar类中

---

Service层

• 还是从业务出发,Service层是调用方,调用方式和Controller层调用Service层一样

class Service {
	constructor(app) {
		const { model } = app;
		Service.prototype.model = model;
	}
	async index() {
		const model = Service.prototype.model;
		let data = awati model.index();
		data.age = 20;
		data.remarks = `forever 18`;
		return data;
	}
}

---

Mar类

• 设计原则是,在不同层之间传递参数,通过Mar类.
• 故需要在Mar类中挂载Model
• 改写Mar类如下

class Mar {
	constructor(conf) {
		this.$app = new koa(conf);
		this.$router = new koaRouter();
		this.model = new Model(this);		// 这一行是新加的
		this.service = new Service(this);
		this.controller = new Controller(this);
		this.router = new Router(this);
	}
	listen(port){	/* 未改变 */}
}

---

Model类 - 初始化

• 新建Mar类如下

class Mar {
	constructor ( app ) {
		console.log('Model ok');
	}
	test() {
		return 'Model for Service'
	}
	async index() {
		return {
			name: 'marron'
		}
	}
}

• 此时启动服务器,访问http://localhost:3000
  

---

Model类-操作数据库

• 准备数据库,按照docker-compose.yml构建容器.
• 浏览器打开管理页面
  
  注: 密码是example
• 新建数据库 marron
  
  
• 准备就绪后,连接数据库,并测试

---

连接数据库

• Sequelize库提供的接口如下

const sequelize = new Sequelize('marron', 'root', 'example', {
    host: 'localhost',
    dialect: 'mysql'
})
sequelize
    .authenticate()
    .then(() => {
        console.log('Connect has been established successfully.');
    })
    .catch(err => {
        console.error('Unable to connect to the database:', err);
    });

• 写到Model类里面

1. 进入Model类的时候,连接到数据库
2. 有一个testSQL方法用于测试,连接数据库是否成功

class Model {
	constructor(app) {
		this.connect();
	}
	connect(){
		this.sequelize = new Sequelize('marron', 'root', 'example', {
			host: 'localhost',
			dialect: 'mysql'
		})
	}
	testSQL() {
		this.sequelize
			.authenticate()
			.then(() =>{
				console.log('Connect has been established successfully.');
			})
			.catch(err =>{
				console.error('Unable to connect to the database:', err);
			})
	}
}

看到这句话时,说明数据库连接成功了

---

表模型

• sequelize提供的接口如下

const User = sequelize.define('user', {
	// 属性
	firstName: {
		type: Sequelize.STRING,
		allowNull: false
	},
	lastName: {
		type: Sequelize.STRING
	},
	{
		// 参数
	}
});

• 加到Model层的addTableUser中

class Model{
	addTable = {
		user: async () => {
			const User = this.sequelize.define('user', {
				// 属性
				name: {
					type: Sequelize.STRING,
					allowNull: false
				},
				date: {
					type: Sequelize.DATE,
					defaultValue: Sequelize.NOW
				}
			});
			// 同步到数据库
			User.sync({ force: true })
		}
	}
}

• 然后在Model的构造函数中调用一次

class Mode {
	constructor(app) {
		this.addTable.user();
	}
}

---

插入一条数据到表中

• 首先要有User表的结构
• 暂时写在Model类的User方法中

class Model () {
	constructor(app) {
	}
	User() {
		return this.sequelize.define('user', {
			// 属性
			name: {
				type: Sequelize.STRING,
				allowNull: false
			},
			date: {
				type: Sequelize.DATE,
				defaultValue: Sequelize.NOW
			}
		})
	}
}

• 写添加user的方法
• 写在add属性下面

class Model () {
	add = {
		user: async (person) => {
			const User = this.User();
			User.create(person);
			// 同步新增用户
			this.sequelize.sync();
		}
	}
}

然后在constructor里面运行一次this.add.user({name:'marron'})

查询数据

class Model {
	find = {
		user: async () => {
			const User = this.User();
			return await User.findAll();
		}
	}
}

---

给Service提供服务

• 前面完成了连接数据库、创建表、往表内插入数据、查询数据的接口
• 下面就是在Model中写一个index方法,给Service层中let data = awati model.index(); 提供服务

class Model () {
	async index() {
		return await this.find.user();
	}
}

---

总代码如下

const koa = require('koa');
const koaRouter = require('koa-router');

class Mar {
    constructor(conf) {
        this.$app = new koa(conf); // 相当于koa的实例
        this.$router = new koaRouter(); // 相当于koa-router的实例
        this.model = new Model(this);
        this.service = new Service(this);
        this.controller = new Controller(this);
        this.router = new Router(this);

    }
    listen(port) {
        this.$app.listen(port, async () => {
            console.log(`[mar]Server is running at http://localhost:${port}`);
        })
    }
}

class Router {
    constructor(app) {
        const { controller, $router, $app } = app;
        $router.get('/', controller.index);
        $app.use($router.routes());
    }
}
class Controller {
    constructor(app) {
        const { service } = app;
        console.log('Controller:', service.test());
        Controller.prototype.service = service;
    }
    test() {
        return 'Controller for Router'
    }
    async index(ctx) {
        const service = Controller.prototype.service;
        ctx.body = await service.index();
    }
}
class Service {
    constructor(app) {
        const { model } = app;
        Service.prototype.model = model;
    }
    test() {
        return 'Service for Controller'
    }
    async index() {
        const model = Service.prototype.model;
        let data = await model.index();
        data.age = '20';
        data.remarks = 'forever 18';
        return data;
    }
}

const Sequelize = require('sequelize');

class Model {
    constructor(app) {
        this.connect();
    }
    // 给其他层的测试函数
    test() {
        return "Model for Service"
    }
    // 连接数据库的函数
    connect() {
        this.sequelize = new Sequelize('marron', 'root', 'example', {
            host: 'localhost',
            dialect: 'mysql'
        })
    }

    // 测试是否连接成功
    testSQL() {
        this.sequelize
            .authenticate()
            .then(() => {
                console.log('Connect has been established successfully.');
            })
            .catch(err => {
                console.error('Unable to connect to the database:', err);
            });
    }
    async index() {
        return await this.find.user()
    }
    addTable = {
        user: async () => {
            const User = this.sequelize.define('user', {
                // 属性
                name: {
                    type: Sequelize.STRING,
                    allowNull: false,
                },
                date: {
                    type: Sequelize.DATE,
                    defaultValue: Sequelize.NOW
                }
            });
            User.sync({ force: true })
        }
    }

    User() {
        return this.sequelize.define('user', {
            // 属性
            name: {
                type: Sequelize.STRING,
                allowNull: false,
            },
            date: {
                type: Sequelize.DATE,
                defaultValue: Sequelize.NOW
            }
        });

    }
    add = {
        user: async (person) => {
            const User = this.User();
            User.create(person);
            // 同步新增用户
            this.sequelize.sync();
        }
    }
    find = {
        user: async () => {
            const User = this.User();
            return await User.findAll();
        }
    }
}

module.exports = Mar;