DRF源码基础

APIView的简单过程

class Request(object):
    def __init__(self, obj):
        self.obj = obj
    @property      # 方法变属性
    def user(self):
        return self.obj.authticate()

class Auth(object):
    def __init__(self, name, age):
        self.name = name
        self.age = age
    def authticate(self):
        return self.name

class APIView(object):
    def dispatch(self):
        self.f2()
    def f2(self):
        a = Auth('Good boys', 18)
        b = Auth('Hello world', 22)
        req = Request(b)
        print(req.user)

obj = APIView()
obj.dispatch()

---

通过列表生成式，生成对象

class first(object):
    pass
class second(object):
    pass

cls = [item() for item() in [first, second]]

---

封装

• 1. 把同一类方法封装至一个类中
• 2. 把数据封装至一个类中

# 与文件相关操作的类
class File:
    ... 文件增删改查方法
# 与数据库相关操作的类
class DB:
    ... 数据库方法

class Data:
    def __init__(self, a1, a2):
        self.a1 = a1
        self.a2 = a2
    def get:     ...
    def delete:  ...
    def update:  ...
    def add:     ...

obj1 = Data(11,12)
obj2 = Data(43,99)

---

反射

• 通过字符串的映射
• 动态操作

hasattr()

• 用于判断对象是否包含对应属性

class A(object):
    x = 1
    y = 2
    z = 3

a = A()
print(hasattr(a, 'x'))    # True
print(hasattr(a, 'y'))    # True
print(hasattr(a, 'z'))    # True
print(hasattr(a, 'w'))    # False

getattr()

• 函数用于返回一个对象属性值, 该属性必须存在

class A(object):
    bar = 1

a = A()
getattr(a, 'bar')    # 1

setattr()

• setattr()函数对应 getattr(), 用于设置属性值

class A(object):
    bar1 = 1

a = A()
print(getattr(a, 'bar1'))    # 1
setattr(a, 'bar1', 5)        # 5
setattr(a, 'bar2', 6)        # 6

delattr()

• delattr 函数用于删除属性

class A(object):
    x = 1
    y = 2
    z = 3

hasattr(A, 'z')    # True
delattr(A, 'z')
hasattr(A, 'z')    # False

---

反射应用例子:

def sing(self):
    print('{}: 在唱歌'.format(self.name))

class User(object):
    def __init__(self, name):
        self.name = name
    def run(self):
        print('{}: 在跑步'.format(self.name))
    def eat(self):
        print('{}: 在吃饭'.format(self.name))

p = User('张三')
send_choices = input('>>>>>>')
if  hasattr(p, send_choices):
    func = getattr(p, send_choices)
    func()
else:
    setattr(p, send_choices, sing) # 对象/ 名字/ 属性
    func = getattr(p, send_choices)
    func()

反射实际例子:

import request

class HTTP(object):
    def get(self):
        res = request.get(url)
        return res.text

    def post(self):
        ...Post的行为...
        res = request.get(url)
        return res.text

url = 'http://www.baidu.com'
method = input(">>>请输入请求方式").lower()
h = HTTP()
if hasattr(h, method):        # 若有方法
    res = getattr(h, method)  # 获取方法
    res = func(url)
    print(res)
else:
    print('请求方式有误')