# -*- coding: utf-8 -*-
# @author : pengj # @time : 2019/1/5 16:40
# @file : myorm.py
import numbers
class field:
pass
class charfield(field):
# 資料描述符
# 好處在於可以在各方法中校驗傳入值的合理性
def __init__(self, col_name, max_length):
if col_name is none or not isinstance(col_name, str):
raise valueerror("col_name must be given as str")
if max_length is none or not isinstance(max_length, numbers.integral):
raise valueerror("max_length must be given as int")
self._col_name = col_name
self._max_length = max_length
def __get__(self, instance, owner):
# return getattr(instance, self._col_name)
return instance.fields[self._col_name]
def __set__(self, instance, value):
# 這裡如果col_name和資料描述符對應的名字一樣的話,如name=charfield(col_name="name",10)
# 用setattr(instance, self._col_name, value)即user.name=value會再次進入此__set__方法,導致無限遞迴
instance.fields[self._col_name] = value
class intfield(field):
def __init__(self, col_name, min_length, max_length):
self._col_name = col_name
self._min_length = min_length
self._max_length = max_length
def __get__(self, instance, owner):
return instance.fields[self._col_name]
def __set__(self, instance, value):
if value is none or (not isinstance(value, numbers.integral)):
raise valueerror("value must be given as int")
instance.fields[self._col_name] = value
class modelmetaclass(type):
def __new__(cls, cls_name, base_class, attrs):
if cls_name == "model":
return super().__new__(cls, cls_name, base_class, attrs)
fields = {}
for k, v in attrs.items():
if isinstance(v, field):
fields[k] = v
attrs["fields"] = fields
_meta = {}
attrs_meta = attrs.get("meta", none)
if attrs_meta is not none and isinstance(attrs_meta, type):
_meta["tb_name"] = getattr(attrs_meta, "tb_name", cls_name)
del attrs["meta"]
else:
_meta["tb_name"] = cls_name.lower()
attrs["_meta"] = _meta
return super().__new__(cls, cls_name, base_class, attrs)
class model(metaclass=modelmetaclass):
def __init__(self, **kwargs):
self.fields = {}
for k, v in kwargs.items():
setattr(self, k, v)
# def more_func(self):
# pass
class user(model):
name = charfield(col_name="name", max_length=10)
*** = charfield(col_name="***", max_length=1)
age = intfield(col_name="age", min_length=1, max_length=10)
class meta:
tb_name = "user"
class company(model):
name = charfield(col_name="name", max_length=10)
address = charfield(col_name="address", max_length=1)
# class meta:
# tb_name = "company"
if __name__ == "__main__":
user = user(name="boy1", age=5, ***="男")
user1 = user(name="girl1", age=6, ***="女")
company = company(name="com", address="china")
print(user.__dict__)
print(user.__dict__)
print(user1.__dict__)
print(company.__dict__)
print(company.__dict__)
, '_meta': , '__doc__': none}}}
, '_meta': , '__doc__': none}
}
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