❥纯手撸ORM❥

from orm.mysql_class import MySql
class Field(object):
    def __init__(self, name, field_type, primary_key, default):
        self.name = name
        self.field_type = field_type
        self.primary_key = primary_key
        self.default = default

class StringField(Field):
    def __init__(self,name,field_type='varchar',primary_key=False,default=None):
        super(StringField, self).__init__(name, field_type, primary_key, default)

class IntegerField(Field):
    def __init__(self,name,field_type='int',primary_key=False,default=0):
        super(IntegerField, self).__init__(name, field_type, primary_key, default)

class MyMetaClass(type):
    def __new__(cls, class_name, class_bases, class_attrs):
        if class_name == 'Models':
            return type.__new__(cls, class_name, class_bases, class_attrs)

        table_name = class_attrs.get('table_name',class_name)
        primary_key = None
        mappings = {}
        for k, v in class_attrs.items():
            if isinstance(v,Field):
                mappings[k] = v
                if v.primary_key:
                    if primary_key:
                        raise TypeError('只能有一个主键')
                    primary_key = v.name
        for i in mappings:
            class_attrs.pop(i)
        if not primary_key:
            raise TypeError('没有主键')
        class_attrs['table_name'] = table_name
        class_attrs['primary_key'] = primary_key
        class_attrs['mappings'] = mappings
        return type.__new__(cls, class_name, class_bases, class_attrs)


class Models(dict,metaclass=MyMetaClass):
    def __init__(self,**kwargs):
        super().__init__(**kwargs)

    def __getattr__(self, item):
        return self.get(item, '没有这个字段')

    def __setattr__(self, key, value):
        self[key] = value

    @classmethod
    def my_select(cls,**kwargs):
        md = MySql()
        if not kwargs:
            sql = "select * from %s"%cls.table_name
            res = md.select(sql)
        else:
            key = list(kwargs.keys())[0]
            values = kwargs.get(key)
            sql = "select * from %s where %s=?"%(cls.table_name,key)
            sql = sql.replace('?','%s')
            res = md.select(sql,values)
            print(res)
        if res:
            return [cls(**i) for i in res]

    def my_insert(self):
        ms = MySql()
        keys = []
        values = []
        wenhao = []
        for k,v in self.mappings.items():
            if not v.primary_key:
                keys.append(v.name)
                values.append(getattr(self,v.name,v.default))
                wenhao.append('?')
        sql = "insert into %s(%s) values(%s)"%(self.table_name,','.join(keys),','.join(wenhao))
        sql = sql.replace('?','%s')
        ms.execute(sql,values)

    def my_update(self):
        ms = MySql()
        field = []
        values = []
        primary_key = None
        for k, v in self.mappings.items():
            if v.primary_key:
                primary_key = getattr(self,v.name,v.default)
            else:
                field.append(v.name+'=?')
                values.append(getattr(self,v.name))
        sql = "update %s set %s where %s=%s"%(
            self.table_name,
            ','.join(field),
            self.primary_key,
            primary_key
        )
        print(self.primary_key)
        print(primary_key)
        sql = sql.replace('?','%s')
        ms.execute(sql,values)