手写ORM第一版

ORM第一版：

#Author = __rianley cheng__

#ORM 简易版

from mysql_ import Mysql

class Fileld:

    def __init__(self,name,colmun_type,primary_key,default):

        self.name=name

        self.colmun_type=colmun_type

        self.primary_key =primary_key

        self.default=default

class Stringfileld(Fileld):

    def __init__(self,name=None,column_type='varchar(200)',primary_key=False,default=None):

        super().__init__(name,column_type,primary_key,default)

class Interfileld(Fileld):

    def __init__(self, name=None, column_type='int', primary_key=False, default=0):

        super().__init__(name, column_type, primary_key, default)

class Model_metaclass(type):

    def __new__(cls, name, bases, attrs):

        if name == 'Model':

            return type.__new__(cls, name, bases, attrs)

        table_name = attrs.get('table_name', None)

        if not table_name:

            table_name = name

        primary_key = None

        mappings = dict()

        for k, v in attrs.items():

            if isinstance(v, Fileld):  # v 是不是Field的对象

                mappings[k] = v

                if v.primary_key:

                    # 找到主键

                    if primary_key:

                        raise TypeError('主键重复：%s' % k)

                    primary_key = k

        for k in mappings.keys():

            attrs.pop(k)

        if not primary_key:

            raise TypeError('没有主键')

        attrs['table_name'] = table_name

        attrs['primary_key'] = primary_key

        attrs['mappings'] = mappings

        return type.__new__(cls, name, bases, attrs)

class Model(dict,metaclass=Model_metaclass):

    def __init__(self,**kwargs):

        super(Model,self).__init__(**kwargs)

    def __getattr__(self, key):  # .访问属性触发

        try:

            return self[key]

        except KeyError:

            raise AttributeError('没有属性：%s' % key)

    def __setattr__(self, key, value):

        self[key] = value

    @classmethod

    def select_all(cls, **kwargs):

        ms = Mysql().singleton()

        if kwargs:  # 当有参数传入的时候

            key = list(kwargs.keys())[0]

            value = kwargs[key]

            sql = "select * from %s where %s=?" % (cls.table_name, key)

            sql = sql.replace('?', '%s')

            res = ms.select(sql, value)

        else:  # 当无参传入的时候查询所有

            sql = "select * from %s" % cls.table_name

            res = ms.select(sql)

        return [cls(**r) for r in res]

    @classmethod

    def select_one(cls, **kwargs):

        # 此处只支持单一条件查询

        key = list(kwargs.keys())[0]

        value = kwargs[key]

        ms = Mysql().singleton()

        sql = "select * from %s where %s=?" % (cls.table_name, key)

        sql = sql.replace('?', '%s')

        res = ms.select(sql, value)

        if res:

            return cls(**res[0])

        else:

            return None

class User(Model):

    table_name = 'User'

    id = Interfileld('id','int',primary_key=True,default=0)

    name = Stringfileld('name')

if __name__ == '__main__':

    user=User().select_one(id='1')

    user1=User().select_all()

    print(user)

    print('=====================>')

    print(user1)

　　

说明

并非是最终版本！ 持续更新中....

每天进步一小点，heiheihei..

作者：rianley  cheng

原创作品，转载请注明出处！