运行效果如下:
Found mapping: uid ==> ('uid', 'int unsigned')Found mapping: password ==> ('password', 'varchar(30)')Found mapping: name ==> ('username', 'varchar(30)')Found mapping: email ==> ('email', 'varchar(30)')SQL: insert into User (email,uid,password,username) values ('test@orm.org',12345,'my-pwd','Michael')4. 抽取到基类中class ModelMetaclass(type): def __new__(cls, name, bases, attrs): mappings = dict() # 判断是否需要保存 for k, v in attrs.items(): # 判断是否是指定的StringField或者IntegerField的实例对象 if isinstance(v, tuple): print('Found mapping: %s ==> %s' % (k, v)) mappings[k] = v # 删除这些已经在字典中存储的属性 for k in mappings.keys(): attrs.pop(k) # 将之前的uid/name/email/password以及对应的对象引用、类名字 attrs['__mappings__'] = mappings # 保存属性和列的映射关系 attrs['__table__'] = name # 假设表名和类名一致 return type.__new__(cls, name, bases, attrs)class Model(object, metaclass=ModelMetaclass): def __init__(self, **kwargs): for name, value in kwargs.items(): setattr(self, name, value) def save(self): fields = [] args = [] for k, v in self.__mappings__.items(): fields.append(v[0]) args.append(getattr(self, k, None)) args_temp = list() for temp in args: # 判断入如果是数字类型 if isinstance(temp, int): args_temp.append(str(temp)) elif isinstance(temp, str): args_temp.append("""'%s'""" % temp) sql = 'insert into %s (%s) values (%s)' % (self.__table__, ','.join(fields), ','.join(args_temp)) print('SQL: %s' % sql)class User(Model): uid = ('uid', "int unsigned") name = ('username', "varchar(30)") email = ('email', "varchar(30)") password = ('password', "varchar(30)")u = User(uid=12345, name='Michael', email='test@orm.org', password='my-pwd')# print(u.__dict__)u.save()
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