orm功能封装

封装功能：

查 ： select

**kwargs.keys() --返回-> obj -转为-->list
[{},{}] ---> [obj,obj]
class Models(dict,metaclass=OSError):
    def __getattr__(self, item):
        #调用没有属性时触发
        return self.get(item)
    def __setattr__(self, key, value):
        self[key] = value
        
    @classmethod
    def orm_select(cls,**kwargs):
        mysql = MySQLClient()
        
        if not kwargs:
            sql = 'select * from %s' %cls.table_name
            
            res = mysql.my_select(sql)
            
        else: 
            key = list(kwargs.keys())[0]
            value = kwargs.get(key)
            
            sql = 'select * from %s where %s=? '%(
                cls.table_name,key
            )
            sql = sql.replace('?','%s')
            res = mysql.my_select(sql,value)
            
        return [cls(**d) for d in res]

增：

    def orm_insert(self):
        mysql = SQLClient()

        keys = []
        values = []
        args = []

        for k , v in self.mappings.items():
            if not v.primary_key:

                keys.append(v.name)

                values.append(
                    getattr(self,v.name,v.default)
                )

                args.append('?')
        sql = 'insert into %s(%s) values(%s)' %(
            self.table_name,
            ','.join(keys),
            ','.join(args)
        )

        sql = sql.replace('?','%s')
        mysql.my_execute(sql,values)

改：

  #更新
  class Models(dict,metaclass=OSError):
    def orm_update(self):
        mysql = SQLClient()

        keys = []
        values = []
        primary_key = None

        for k,v in self.mappings.items():
            if v.primary_key:
                primary_key = v.name + '= %s' % getattr(self,v.name)

            else:
                keys.append(v.name + '=?')
                values.append(
                    getattr(self,v.name)
                )

        sql = 'update %s set %s where %s' %(
            self.table_name,
            ','.join(keys),
            primary_key
        )
        sql = sql.replace('?','%s')
        mysql.my_execute(sql,values)

连接数据库:

连接数据库
import pymysql

class MySQLClient:
    def __init__(self):
        
        self.client = pymysql.connect(
            host ='localhost',
            port = 3306,
            user= 'root',
            password = '123',
            database = 'orm_demo',
            charset = 'utf-8',
            auto_increment = True
            
        )
        self.cursor = self.client.cursor(
            pymysql.cursors.DictCursor
        )
        
        def my_select(self,sql,value=None):
            self.cursor.execute(sql,value)
            
            res = self.cursor.fetchall()
            
            return res

        def my_execute(self, sql, values):
            try:
                self.cursor.execute(sql, values)

            except Exception as e:
                print(e)

        def close(self):
            self.cursor.close()
            self.client.close()

操作系统 ： C

手机应用： iphone swift / objective-c

​ android java

​ 3D : C / C ++

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