68 lines
1.9 KiB
Python
68 lines
1.9 KiB
Python
# -*- coding: utf-8 -*-
|
||
"""
|
||
Day_5 参考解答
|
||
=============
|
||
主题：面向对象（二）—— 继承。
|
||
建议：先自己写，写不出来再看；看完后关掉文件自己默写一遍。
|
||
"""
|
||
|
||
import time
|
||
|
||
class BaseModel:
|
||
objects = [] # 类属性：模拟数据库表（所有子类共用）
|
||
|
||
def save(self):
|
||
BaseModel.objects.append(self)
|
||
print(f"[DB] 已保存 {type(self).__name__}: {self}")
|
||
|
||
def delete(self):
|
||
BaseModel.objects.remove(self)
|
||
print(f"[DB] 已删除 {self}")
|
||
|
||
def to_dict(self):
|
||
return dict(self.__dict__) # 实例的所有属性 => 字典
|
||
|
||
def __str__(self):
|
||
return f"<{type(self).__name__}#{id(self)}>"
|
||
|
||
|
||
class Article(BaseModel):
|
||
def __init__(self, title, content, author):
|
||
self.title = title
|
||
self.content = content
|
||
self.author = author
|
||
self.created_at = time.strftime("%Y-%m-%d %H:%M:%S")
|
||
|
||
# 进阶：重写 save，先打日志，再调用父类逻辑
|
||
def save(self):
|
||
print(f"[LOG] 正在保存文章《{self.title}》...")
|
||
super().save() # 父类的 save 负责真正"入库"
|
||
|
||
def __str__(self):
|
||
return f"<Article: {self.title}>"
|
||
|
||
|
||
class Comment(BaseModel):
|
||
def __init__(self, content, author):
|
||
self.content = content
|
||
self.author = author
|
||
|
||
def __str__(self):
|
||
return f"<Comment: {self.content[:10]}...>"
|
||
|
||
|
||
if __name__ == '__main__':
|
||
a1 = Article("Django 入门", "从 Hello World 开始", "zhangsan")
|
||
a1.save() # 触发重写后的 save（带日志 + super）
|
||
c1 = Comment("写得太好了！", "lisi")
|
||
c1.save()
|
||
|
||
for obj in BaseModel.objects:
|
||
print(obj.to_dict())
|
||
|
||
print(issubclass(Article, BaseModel)) # True
|
||
print(isinstance(a1, BaseModel)) # True
|
||
|
||
a1.delete()
|
||
print(len(BaseModel.objects)) # 1（只剩评论）
|