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有了ORM,我们就可以把Web App需要的3个表用Model
表示出来:
import time, uuid
from orm import Model, StringField, BooleanField, FloatField, TextField
def next_id():
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)
在编写ORM时,给一个Field增加一个default
参数可以让ORM自己填入缺省值,非常方便。并且,缺省值可以作为函数对象传入,在调用save()
时自动计算。
例如,主键id
的缺省值是函数next_id
,创建时间created_at
的缺省值是函数time.time
,可以自动设置当前日期和时间。
日期和时间用float
类型存储在数据库中,而不是datetime
类型,这么做的好处是不必关心数据库的时区以及时区转换问题,排序非常简单,显示的时候,只需要做一个float
到str
的转换,也非常容易。
初始化数据库表
如果表的数量很少,可以手写创建表的SQL脚本:
-- 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;
如果表的数量很多,可以从Model
对象直接通过脚本自动生成SQL脚本,使用更简单。
把SQL脚本放到MySQL命令行里执行:
$ mysql -u root -p < schema.sql
我们就完成了数据库表的初始化。
编写数据访问代码
接下来,就可以真正开始编写代码操作对象了。比如,对于User
对象,我们就可以做如下操作:
import orm
from models import User, Blog, Comment
def test():
yield from orm.create_pool(user='www-data', password='www-data', database='awesome')
u = User(name='Test', email='test@example.com', passwd='1234567890', image='about:blank')
yield from u.save()
for x in test():
pass
可以在MySQL客户端命令行查询,看看数据是不是正常存储到MySQL里面了。
参考源码
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