Python3教程Web开发实战梳理-day4（编写Model）

Day4-编写Model

在day3的实战中，我们编写了ORM，在ORM模块里我们编写了Model类，这是一个基类，定义了一些基本的类方法。今天要写的Model是对昨天的Model再进行抽象。我们的网站目标是搭建一个博客，因此我们我们要创建User, Blog和Comment三个不同的model，并初始化三个数据库表。

Models.py：

import time, uuidfrom orm import Model, StringField, BooleanField, FloatField, TextFielddef next_id():  #随机生成id的方法    return '%015d%s000' % (int(time.time()*1000), uuid.uuid4().hex)class User(Model):    __table__ = 'users'    id=StringField(primary_key=True, default=next_id, ddl='varchar(50)')    email = StringField(ddl='varchar(50)')    passwd = StringField(ddl='varchar(50)')    admin = BooleanField()    name = StringField(ddl='varchar(50)')    image = StringField(ddl='varchar(500)')    created_at = FloatField(default=time.time)class Blog(Model):    __table__ = 'blogs'    id = StringField(primary_key=True, default=next_id, ddl='varchar(50)')    user_id = StringField(ddl='varchar(50)')    user_name = StringField(ddl='varchar(50)')    user_image = StringField(ddl='varchar(500)')    name = StringField(ddl='varchar(50)')    summary = StringField(ddl='varchar(200)')    content = TextField()    created_at = FloatField(default=time.time)class Comment(Model):    __table__ = 'comments'    id = StringField(primary_key=True, default=next_id, ddl='varchar(50)')    blog_id = StringField(ddl='varchar(50)')    user_id = StringField(ddl='varchar(50)')    user_name = StringField(ddl='varchar(50)')    user_image = StringField(ddl='varchar(500)')    content = TextField()    created_at = FloatField(default=time.time)#测试部分if __name__== '__main__':    async def test():        await orm.create_pool(loop,user='www-data', password='www-data', db='awesome')        u = User(name='Test', email='[e-mail]', passwd='123456780', image='about:blank')        await u.save()        a = await u.findall() #这个要打印才显示出来        print(a)    loop = asyncio.get_event_loop()    loop.run_until_complete(test())    orm.__pool.close()  #在关闭event loop之前，首先需要关闭连接池。    loop.run_until_complete(orm.__pool.wait_closed())#在关闭event loop之前，首先需要关闭连接池。    loop.close()

初始化数据库表 schema.sql：

drop database if exists awesome;create database awesome;use awesome;grant select, insert, update, delete on awesome.* to 'www-data'@'localhost' identified by 'www-data';create table users (    `id` varchar(50) not null,    `email` varchar(50) not null,    `passwd` varchar(50) not null,    `admin` bool not null,    `name` varchar(50) not null,    `image` varchar(500) not null,    `created_at` real not null,    unique key `idx_email` (`email`),    key `idx_created_at` (`created_at`),    primary key (`id`)) engine=innodb default charset=utf8;create table blogs (    `id` varchar(50) not null,    `user_id` varchar(50) not null,    `user_name` varchar(50) not null,    `user_image` varchar(500) not null,    `name` varchar(50) not null,    `summary` varchar(200) not null,    `content` mediumtext not null,    `created_at` real not null,    key `idx_created_at` (`created_at`),    primary key (`id`)) engine=innodb default charset=utf8;create table comments (    `id` varchar(50) not null,    `blog_id` varchar(50) not null,    `user_id` varchar(50) not null,    `user_name` varchar(50) not null,    `user_image` varchar(500) not null,    `content` mediumtext not null,    `created_at` real not null,    key `idx_created_at` (`created_at`),    primary key (`id`)) engine=innodb default charset=utf8;

将以上代码保存为sql文件后，在命令行下或者可视化工具中执行该文件即可。
注意：该操作前提是需要提前手动创建名为 awesome 的数据库

小结

至此，我们完成了ORM与Model的编写，像之前所说的，相当于在程序中创建了一个虚拟数据库，在以后的开发中，我们只需要对User Blog Comment三个Model进行操作就可以了，而不需要再去关心他们是如何去与数据库交互的。这就是封装的好处，也是ORM广为采用的原因。