ORM 实现类与表，类属性与字段的映射关系

# 类 -> 表
# 类属性 -> 字段

class model:

    def __init__(self, max_length=100):
        self.max_length = max_length
        self.table = self.__class__.__name__
        self.fields = [i for i in dir(self) if i not in ['save', 'table', 'max_length'] and i[0:2] != '__']
        values = [getattr(self, i) for i in self.fields]

    def save(self):
        table = self.table
        fields = self.fields
        fields_sql = [f'`%s` varchar({
      self.max_length}) not null,\n' % i for i in fields]
        my_fields_sql = "".join(fields_sql)
        sql = f'''create table if not exists `{
      table}`(`id` int unsigned auto_increment,\n''' + my_fields_sql + 'primary key (`id`))engine=InnoDB default charset=utf8; '
        print(sql)


class CharField(model):
    pass


class Cat(model):
    head = CharField(max_length=200)
    foot = CharField()


Cat().save()

输出结果:

create table if not exists `Cat`(`id` int unsigned auto_increment,
`foot` varchar(100) not null,
`head` varchar(100) not null,
primary key (`id`))engine=InnoDB default charset=utf8;