>>> class ObjectCreator(object):
...       pass
...

>>> my_object = ObjectCreator()
>>> print(my_object)
<__main__.ObjectCreator object at 0x8974f2c>

>>> class ObjectCreator(object):
...       pass
...

>>> print(ObjectCreator) # 你可以打印一个类,因为它是一个对象
<class '__main__.ObjectCreator'>
>>> def echo(o):
...       print(o)
...
>>> echo(ObjectCreator) # 你可以把类作为参数传递
<class '__main__.ObjectCreator'>
>>> print(hasattr(ObjectCreator, 'new_attribute'))
False
>>> ObjectCreator.new_attribute = 'foo' # 可以给一个类添加属性
>>> print(hasattr(ObjectCreator, 'new_attribute'))
True
>>> print(ObjectCreator.new_attribute)
foo
>>> ObjectCreatorMirror = ObjectCreator # 可以把类赋值给一个变量
>>> print(ObjectCreatorMirror.new_attribute)
foo
>>> print(ObjectCreatorMirror())
<__main__.ObjectCreator object at 0x8997b4c>

>>> def choose_class(name):
...     if name == 'foo':
...         class Foo(object):
...             pass
...         return Foo # 返回一个类不是一个实例
...     else:
...         class Bar(object):
...             pass
...         return Bar
...
>>> MyClass = choose_class('foo')
>>> print(MyClass) # 返回一个类不是一个实例
<class '__main__.Foo'>
>>> print(MyClass()) # 你可以在类里创建一个对象
<__main__.Foo object at 0x89c6d4c>

>>> print(type(1))
<type 'int'>
>>> print(type("1"))
<type 'str'>
>>> print(type(ObjectCreator))
<type 'type'>
>>> print(type(ObjectCreator()))
<class '__main__.ObjectCreator'>

type(类名,
     父类名的元组 (针对继承情况,可以为空),
     包含属性的字典(名称和值))

>>> class MyShinyClass(object):
...       pass

>>> MyShinyClass = type('MyShinyClass', (), {}) # 返回类对象
>>> print(MyShinyClass)
<class '__main__.MyShinyClass'>
>>> print(MyShinyClass()) # 创建一个类的实例
<__main__.MyShinyClass object at 0x8997cec>

>>> class Foo(object):
...       bar = True

>>> Foo = type('Foo', (), {'bar':True})

>>> print(Foo)
<class '__main__.Foo'>
>>> print(Foo.bar)
True
>>> f = Foo()
>>> print(f)
<__main__.Foo object at 0x8a9b84c>
>>> print(f.bar)
True

>>>   class FooChild(Foo):
...         pass

>>> FooChild = type('FooChild', (Foo,), {})
>>> print(FooChild)
<class '__main__.FooChild'>
>>> print(FooChild.bar) # bar从Foo继承
True

>>> def echo_bar(self):
...       print(self.bar)
...
>>> FooChild = type('FooChild', (Foo,), {'echo_bar': echo_bar})
>>> hasattr(Foo, 'echo_bar')
False
>>> hasattr(FooChild, 'echo_bar')
True
>>> my_foo = FooChild()
>>> my_foo.echo_bar()
True

MyClass = MetaClass()
MyObject = MyClass()

MyClass = type('MyClass', (), {})

>>> age = 35
>>> age.__class__
<type 'int'>
>>> name = 'bob'
>>> name.__class__
<type 'str'>
>>> def foo(): pass
>>> foo.__class__
<type 'function'>
>>> class Bar(object): pass
>>> b = Bar()
>>> b.__class__
<class '__main__.Bar'>

>>> age.__class__.__class__
<type 'type'>
>>> name.__class__.__class__
<type 'type'>
>>> foo.__class__.__class__
<type 'type'>
>>> b.__class__.__class__
<type 'type'>

class Foo(object):
  __metaclass__ = something...
  [...]

class Foo(Bar):
  pass

# 元类会自动将你通常传给'type'的参数作为自己的参数传入
def upper_attr(future_class_name, future_class_parents, future_class_attr):
  """
    返回一个将属性列表变为大写字母的类对象
  """

  # 选取所有不以'__'开头的属性,并把它们编程大写
  uppercase_attr = {}
  for name, val in future_class_attr.items():
      if not name.startswith('__'):
          uppercase_attr[name.upper()] = val
      else:
          uppercase_attr[name] = val

  # 用'type'创建类
  return type(future_class_name, future_class_parents, uppercase_attr)

__metaclass__ = upper_attr # 将会影响整个模块

class Foo(): # global __metaclass__ won't work with "object" though
  # 我们也可以只在这里定义__metaclass__，这样就只会作用于这个类中
  bar = 'bip'

print(hasattr(Foo, 'bar'))
# 输出: False
print(hasattr(Foo, 'BAR'))
# 输出: True

f = Foo()
print(f.BAR)
# 输出: 'bip'

# 请记住，'type'实际上是一个类，就像'str'和'int'一样
# 所以，你可以从type继承
class UpperAttrMetaclass(type):
    # __new__ 是在__init__之前被调用的特殊方法
    # __new__是用来创建对象并返回它的方法
    # 而__init__只是用来将传入的参数初始化给对象
    # 你很少用到__new__，除非你希望能够控制对象的创建
    # 这里，创建的对象是类，我们希望能够自定义它，所以我们这里改写__new__
    # 如果你希望的话，你也可以在__init__中做些事情
    # 还有一些高级的用法会涉及到改写__call__特殊方法，但是我们这里不用
    def __new__(upperattr_metaclass, future_class_name,
                future_class_parents, future_class_attr):

        uppercase_attr = {}
        for name, val in future_class_attr.items():
            if not name.startswith('__'):
                uppercase_attr[name.upper()] = val
            else:
                uppercase_attr[name] = val

        return type(future_class_name, future_class_parents, uppercase_attr)

class UpperAttrMetaclass(type):

    def __new__(upperattr_metaclass, future_class_name,
                future_class_parents, future_class_attr):

        uppercase_attr = {}
        for name, val in future_class_attr.items():
            if not name.startswith('__'):
                uppercase_attr[name.upper()] = val
            else:
                uppercase_attr[name] = val

        # 重用 type.__new__ 方法
        # 这就是基本的OOP编程，没什么魔法
        return type.__new__(upperattr_metaclass, future_class_name,
                            future_class_parents, uppercase_attr)

class UpperAttrMetaclass(type):

    def __new__(cls, clsname, bases, dct):

        uppercase_attr = {}
        for name, val in dct.items():
            if not name.startswith('__'):
                uppercase_attr[name.upper()] = val
            else:
                uppercase_attr[name] = val

        return type.__new__(cls, clsname, bases, uppercase_attr)

class UpperAttrMetaclass(type):

    def __new__(cls, clsname, bases, dct):

        uppercase_attr = {}
        for name, val in dct.items():
            if not name.startswith('__'):
                uppercase_attr[name.upper()] = val
            else:
                uppercase_attr[name] = val

        return super(UpperAttrMetaclass, cls).__new__(cls, clsname, bases, uppercase_attr)

class Person(models.Model):
  name = models.CharField(max_length=30)
  age = models.IntegerField()

guy = Person(name='bob', age='35')
print(guy.age)

>>> class Foo(object): pass
>>> id(Foo)
142630324

import time
import asyncio

now = lambda : time.time()

async def do_some_work(x):
    print('Waiting: ', x)

start = now()

coroutine = do_some_work(2)

loop = asyncio.get_event_loop()
loop.run_until_complete(coroutine)

print('TIME: ', now() - start)

import asyncio
import time

now = lambda : time.time()

async def do_some_work(x):
    print('Waiting: ', x)

start = now()

coroutine = do_some_work(2)
loop = asyncio.get_event_loop()
# task = asyncio.ensure_future(coroutine)
task = loop.create_task(coroutine)
print(task)
loop.run_until_complete(task)
print(task)
print('TIME: ', now() - start)

import time
import asyncio

now = lambda : time.time()

async def do_some_work(x):
    print('Waiting: ', x)
    return 'Done after {}s'.format(x)

def callback(future):
    print('Callback: ', future.result())

start = now()

coroutine = do_some_work(2)
loop = asyncio.get_event_loop()
task = asyncio.ensure_future(coroutine)
task.add_done_callback(callback)
loop.run_until_complete(task)

print('TIME: ', now() - start)

async def do_some_work(x):
    print('Waiting {}'.format(x))
    return 'Done after {}s'.format(x)

start = now()

coroutine = do_some_work(2)
loop = asyncio.get_event_loop()
task = asyncio.ensure_future(coroutine)
loop.run_until_complete(task)

print('Task ret: {}'.format(task.result()))
print('TIME: {}'.format(now() - start))

Waiting:  2
Task ret:  Done after 2s
TIME:  0.0003650188446044922

import asyncio
import time

now = lambda: time.time()

async def do_some_work(x):
    print('Waiting: ', x)
    await asyncio.sleep(x)
    return 'Done after {}s'.format(x)

start = now()

coroutine = do_some_work(2)
loop = asyncio.get_event_loop()
task = asyncio.ensure_future(coroutine)
loop.run_until_complete(task)

print('Task ret: ', task.result())
print('TIME: ', now() - start)

import asyncio

import time

now = lambda: time.time()

async def do_some_work(x):
    print('Waiting: ', x)

    await asyncio.sleep(x)
    return 'Done after {}s'.format(x)

start = now()

coroutine1 = do_some_work(1)
coroutine2 = do_some_work(2)
coroutine3 = do_some_work(4)

tasks = [
    asyncio.ensure_future(coroutine1),
    asyncio.ensure_future(coroutine2),
    asyncio.ensure_future(coroutine3)
]

loop = asyncio.get_event_loop()
loop.run_until_complete(asyncio.wait(tasks))

for task in tasks:
    print('Task ret: ', task.result())

print('TIME: ', now() - start)

Waiting:  1
Waiting:  2
Waiting:  4
Task ret:  Done after 1s
Task ret:  Done after 2s
Task ret:  Done after 4s
TIME:  4.003541946411133

import asyncio

import time

now = lambda: time.time()

async def do_some_work(x):
    print('Waiting: ', x)

    await asyncio.sleep(x)
    return 'Done after {}s'.format(x)

async def main():
    coroutine1 = do_some_work(1)
    coroutine2 = do_some_work(2)
    coroutine3 = do_some_work(4)

    tasks = [
        asyncio.ensure_future(coroutine1),
        asyncio.ensure_future(coroutine2),
        asyncio.ensure_future(coroutine3)
    ]

    dones, pendings = await asyncio.wait(tasks)

    for task in dones:
        print('Task ret: ', task.result())

start = now()

loop = asyncio.get_event_loop()
loop.run_until_complete(main())

print('TIME: ', now() - start)

results = await asyncio.gather(*tasks)

    for result in results:
        print('Task ret: ', result)

async def main():
    coroutine1 = do_some_work(1)
    coroutine2 = do_some_work(2)
    coroutine3 = do_some_work(2)

    tasks = [
        asyncio.ensure_future(coroutine1),
        asyncio.ensure_future(coroutine2),
        asyncio.ensure_future(coroutine3)
    ]

    return await asyncio.gather(*tasks)

start = now()

loop = asyncio.get_event_loop()
results = loop.run_until_complete(main())

for result in results:
    print('Task ret: ', result)

async def main():
    coroutine1 = do_some_work(1)
    coroutine2 = do_some_work(2)
    coroutine3 = do_some_work(4)

    tasks = [
        asyncio.ensure_future(coroutine1),
        asyncio.ensure_future(coroutine2),
        asyncio.ensure_future(coroutine3)
    ]

    return await asyncio.wait(tasks)

start = now()

loop = asyncio.get_event_loop()
done, pending = loop.run_until_complete(main())

for task in done:
    print('Task ret: ', task.result())

async def main():
    coroutine1 = do_some_work(1)
    coroutine2 = do_some_work(2)
    coroutine3 = do_some_work(4)

    tasks = [
        asyncio.ensure_future(coroutine1),
        asyncio.ensure_future(coroutine2),
        asyncio.ensure_future(coroutine3)
    ]
    for task in asyncio.as_completed(tasks):
        result = await task
        print('Task ret: {}'.format(result))

start = now()

loop = asyncio.get_event_loop()
done = loop.run_until_complete(main())
print('TIME: ', now() - start)

import asyncio

import time

now = lambda: time.time()

async def do_some_work(x):
    print('Waiting: ', x)

    await asyncio.sleep(x)
    return 'Done after {}s'.format(x)

coroutine1 = do_some_work(1)
coroutine2 = do_some_work(2)
coroutine3 = do_some_work(2)

tasks = [
    asyncio.ensure_future(coroutine1),
    asyncio.ensure_future(coroutine2),
    asyncio.ensure_future(coroutine3)
]

start = now()

loop = asyncio.get_event_loop()
try:
    loop.run_until_complete(asyncio.wait(tasks))
except KeyboardInterrupt as e:
    print(asyncio.Task.all_tasks())
    for task in asyncio.Task.all_tasks():
        print(task.cancel())
    loop.stop()
    loop.run_forever()
finally:
    loop.close()

print('TIME: ', now() - start)

Waiting:  1
Waiting:  2
Waiting:  2
{<Task pending coro=<do_some_work() running at...
True
True
True
True
TIME:  0.8858370780944824

Task was destroyed but it is pending!
task: <Task pending coro=<do_some_work() done,

import asyncio

import time

now = lambda: time.time()

async def do_some_work(x):
    print('Waiting: ', x)

    await asyncio.sleep(x)
    return 'Done after {}s'.format(x)

async def main():
    coroutine1 = do_some_work(1)
    coroutine2 = do_some_work(2)
    coroutine3 = do_some_work(2)

    tasks = [
        asyncio.ensure_future(coroutine1),
        asyncio.ensure_future(coroutine2),
        asyncio.ensure_future(coroutine3)
    ]
    done, pending = await asyncio.wait(tasks)
    for task in done:
        print('Task ret: ', task.result())

start = now()

loop = asyncio.get_event_loop()
task = asyncio.ensure_future(main())
try:
    loop.run_until_complete(task)
except KeyboardInterrupt as e:
    print(asyncio.Task.all_tasks())
    print(asyncio.gather(*asyncio.Task.all_tasks()).cancel())
    loop.stop()
    loop.run_forever()
finally:
    loop.close()

from threading import Thread

def start_loop(loop):
    asyncio.set_event_loop(loop)
    loop.run_forever()

def more_work(x):
    print('More work {}'.format(x))
    time.sleep(x)
    print('Finished more work {}'.format(x))

start = now()
new_loop = asyncio.new_event_loop()
t = Thread(target=start_loop, args=(new_loop,))
t.start()
print('TIME: {}'.format(time.time() - start))

new_loop.call_soon_threadsafe(more_work, 6)
new_loop.call_soon_threadsafe(more_work, 3)

def start_loop(loop):
    asyncio.set_event_loop(loop)
    loop.run_forever()

async def do_some_work(x):
    print('Waiting {}'.format(x))
    await asyncio.sleep(x)
    print('Done after {}s'.format(x))

def more_work(x):
    print('More work {}'.format(x))
    time.sleep(x)
    print('Finished more work {}'.format(x))

start = now()
new_loop = asyncio.new_event_loop()
t = Thread(target=start_loop, args=(new_loop,))
t.start()
print('TIME: {}'.format(time.time() - start))

asyncio.run_coroutine_threadsafe(do_some_work(6), new_loop)
asyncio.run_coroutine_threadsafe(do_some_work(4), new_loop)

while True:
        task = rcon.rpop("queue")
        if not task:
            time.sleep(1)
            continue
        asyncio.run_coroutine_threadsafe(do_some_work(int(task)), new_loop)

127.0.0.1:6379[3]> lpush queue 2
(integer) 1
127.0.0.1:6379[3]> lpush queue 5
(integer) 1
127.0.0.1:6379[3]> lpush queue 1
(integer) 1
127.0.0.1:6379[3]> lpush queue 1

Waiting  2
Done 2
Waiting  5
Waiting  1
Done 1
Waiting  1
Done 1
Done 5

try:
    while True:
        task = rcon.rpop("queue")
        if not task:
            time.sleep(1)
            continue
        asyncio.run_coroutine_threadsafe(do_some_work(int(task)), new_loop)
except KeyboardInterrupt as e:
    print(e)
    new_loop.stop()

new_loop = asyncio.new_event_loop()
t = Thread(target=start_loop, args=(new_loop,))
t.setDaemon(True)    # 设置子线程为守护线程
t.start()

try:
    while True:
        # print('start rpop')
        task = rcon.rpop("queue")
        if not task:
            time.sleep(1)
            continue
        asyncio.run_coroutine_threadsafe(do_some_work(int(task)), new_loop)
except KeyboardInterrupt as e:
    print(e)
    new_loop.stop()

import time
from flask import Flask, request

app = Flask(__name__)

@app.route('/<int:x>')
def index(x):
    time.sleep(x)
    return "{} It works".format(x)

@app.route('/error')
def error():
    time.sleep(3)
    return "error!"

if __name__ == '__main__':
    app.run(debug=True)

import time
import asyncio
from threading import Thread
import redis
import aiohttp

def get_redis():
    connection_pool = redis.ConnectionPool(host='127.0.0.1', db=3)
    return redis.Redis(connection_pool=connection_pool)

rcon = get_redis()

def start_loop(loop):
    asyncio.set_event_loop(loop)
    loop.run_forever()

async def fetch(url):
    async with aiohttp.ClientSession() as session:
        async with session.get(url) as resp:
            print(resp.status)
            return await resp.text()

async def do_some_work(x):
    print('Waiting ', x)
    try:
        ret = await fetch(url='http://127.0.0.1:5000/{}'.format(x))
        print(ret)
    except Exception as e:
        try:
            print(await fetch(url='http://127.0.0.1:5000/error'))
        except Exception as e:
            print(e)
    else:
        print('Done {}'.format(x))

new_loop = asyncio.new_event_loop()
t = Thread(target=start_loop, args=(new_loop,))
t.setDaemon(True)
t.start()

try:
    while True:
        task = rcon.rpop("queue")
        if not task:
            time.sleep(1)
            continue
        asyncio.run_coroutine_threadsafe(do_some_work(int(task)), new_loop)
except Exception as e:
    print('error')
    new_loop.stop()
finally:
    pass

try:
    while True:
        _, task = rcon.brpop("queue")
        asyncio.run_coroutine_threadsafe(do_some_work(int(task)), new_loop)
except Exception as e:
    print('error', e)
    new_loop.stop()
finally:
    pass

127.0.0.1:6379[3]> lpush queue 5
(integer) 1
127.0.0.1:6379[3]> lpush queue 1
(integer) 1
127.0.0.1:6379[3]> lpush queue 1

Waiting  5
Waiting  1
Waiting  1
200
1 It works
Done 1
200
1 It works
Done 1
200
5 It works
Done 5

import time
import asyncio
import redis

now = lambda : time.time()

def get_redis():
    connection_pool = redis.ConnectionPool(host='127.0.0.1', db=3)
    return redis.Redis(connection_pool=connection_pool)

rcon = get_redis()

async def worker():
    print('Start worker')

    while True:
        start = now()
        task = rcon.rpop("queue")
        if not task:
            await asyncio.sleep(1)
            continue
        print('Wait ', int(task))
        await asyncio.sleep(int(task))
        print('Done ', task, now() - start)

def main():
    asyncio.ensure_future(worker())
    asyncio.ensure_future(worker())

    loop = asyncio.get_event_loop()
    try:
        loop.run_forever()
    except KeyboardInterrupt as e:
        print(asyncio.gather(*asyncio.Task.all_tasks()).cancel())
        loop.stop()
        loop.run_forever()
    finally:
        loop.close()

if __name__ == '__main__':
    main()

>>> class MyClass():
...     def __init__(self):
...             self.__superprivate = "Hello"
...             self._semiprivate = ", world!"
...
>>> mc = MyClass()
>>> print mc.__superprivate
Traceback (most recent call last):
  File "<stdin>", line 1, in <module>
AttributeError: myClass instance has no attribute '__superprivate'
>>> print mc._semiprivate
, world!
>>> print mc.__dict__
{'_MyClass__superprivate': 'Hello', '_semiprivate': ', world!'}

class Singleton(object):
    def __new__(cls, *args, **kw):
        if not hasattr(cls, '_instance'):
            orig = super(Singleton, cls)
            cls._instance = orig.__new__(cls, *args, **kw)
        return cls._instance

class MyClass(Singleton):
    a = 1

class Borg(object):
    _state = {}
    def __new__(cls, *args, **kw):
        ob = super(Borg, cls).__new__(cls, *args, **kw)
        ob.__dict__ = cls._state
        return ob

class MyClass2(Borg):
    a = 1

def singleton(cls, *args, **kw):
    instances = {}
    def getinstance():
        if cls not in instances:
            instances[cls] = cls(*args, **kw)
        return instances[cls]
    return getinstance

@singleton
class MyClass:
  ...

# mysingleton.py
class My_Singleton(object):
    def foo(self):
        pass

my_singleton = My_Singleton()

# to use
from mysingleton import my_singleton

my_singleton.foo()

import threading
from contextlib import contextmanager

# Thread-local state to stored information on locks already acquired
_local = threading.local()

@contextmanager
def acquire(*locks):
    # Sort locks by object identifier
    locks = sorted(locks, key=lambda x: id(x))

    # Make sure lock order of previously acquired locks is not violated
    acquired = getattr(_local,'acquired',[])
    if acquired and max(id(lock) for lock in acquired) >= id(locks[0]):
        raise RuntimeError('Lock Order Violation')

    # Acquire all of the locks
    acquired.extend(locks)
    _local.acquired = acquired

    try:
        for lock in locks:
            lock.acquire()
        yield
    finally:
        # Release locks in reverse order of acquisition
        for lock in reversed(locks):
            lock.release()
        del acquired[-len(locks):]

>>> res = add.delay(2)
>>> res.failed()
True
>>> res.successful()
False
# 查看任务状态，典型的任务阶段是：PENDING -> STARTED -> SUCCESS
>>> res.state
'FAILURE'
启动状态是一种特殊状态，仅在task_track_started启用该设置或 仅为@task(track_started=True)该任务设置选项时才会记录 。

>>> add.signature((2, 2), countdown=10)
tasks.add(2, 2)

>>> add.s(2, 2)
tasks.add(2, 2)

创建不完整的签名来创建我们称之为 partials的内容：
# incomplete partial: add(?, 2)
>>> s2 = add.s(2)

s2 现在是一个部分签名，需要另一个参数完成，这可以在调用签名时解决：
# resolves the partial: add(8, 2)
>>> res = s2.delay(8)
>>> res.get()
10

一个任务返回后调用另一个任务：
```python
>>> from celery import chain
>>> from proj.tasks import add, mul
# (4 + 4) * 8
>>> chain(add.s(4, 4) | mul.s(8))().get()
64

或部分链：
>>> # (? + 4) * 8
>>> g = chain(add.s(4) | mul.s(8))
>>> g(4).get()
64

链也可以这样写：
>>> (add.s(4, 4) | mul.s(8))().get()
64

@app.task
def update_page_info(url):
    page = fetch_page.delay(url).get()
    info = parse_page.delay(url, page).get()
    store_page_info.delay(url, info)

@app.task
def fetch_page(url):
    return myhttplib.get(url)

@app.task
def parse_page(url, page):
    return myparser.parse_document(page)

@app.task
def store_page_info(url, info):
    return PageInfo.objects.create(url, info)

def update_page_info(url):
    # fetch_page -> parse_page -> store_page
    chain = fetch_page.s(url) | parse_page.s() | store_page_info.s(url)
    chain()

@app.task()
def fetch_page(url):
    return myhttplib.get(url)

@app.task()
def parse_page(page):
    return myparser.parse_document(page)

@app.task(ignore_result=True)
def store_page_info(info, url):
    PageInfo.objects.create(url=url, info=info)

fetch_page.apply_async((url), link=[parse_page.s(), store_page_info.s(url)])

app.conf.update(
    task_routes = {
        'proj.tasks.add': {'queue': 'hipri'},
    },
)

>>> from proj.tasks import add
>>> add.apply_async((2, 2), queue='hipri')

>>> app.conf.timezone
'Europe/London'

>>> app.conf.update(
...     enable_utc=True,
...     timezone='Europe/London',
...)

from django.core  import serializers
from django.http import JsonResponse

def get_users:
    ret = {}
    users = models.UserInfo.objects.all()
    # 序列化QuerySet
    ret['users'] = serializers.serialize('json', users)
    return JsonResponse(ret)

from django.core  import serializers
from django.http import JsonResponse

def get_users:
    ret = {}
    users = models.UserInfo.objects.all().values('id', 'username')
    # 序列化QuerySet
    # ret['users'] = serializers.serialize('json', users)
    ret['users'] = list(users)

    return JsonResponse(ret)

# 添加csrf_exempt装饰器的函数免除csrf_token验证，添加csrf_protect装饰器的函数需要csrf_token验证
from django.views.decorators.csrf import csrf_exempt, csrf_protect

# CBV中csrf_token处理，需要在dispatch方法中加装饰器将csrf_exempt, csrf_protect当作参数传入
from django.utils.decorators import method_decorator
from django.views.decorators.csrf import csrf_exempt, csrf_protect
@method_decorator(csrf_exempt)
def dispatch(self, request, *args, **kwargs)...

# 或者

@method_decorator(csrf_exempt, name='dispatch')
class ClassName()...

from django.template import loader
from django.template.loader import render_to_string

ret = loader.render_to_string('secondPage/news_snippet.html', {'articles': index_article}, request=request)
return HttpResponse(ret)

from rest_framework import serializers
class UserInfoSerializer(serializers.Serializer):
    xxx = serializers.CharField(source="get_user_type_display") choices
    name = serializers.CharField()
    age = serializers.IntegerField()
    gp = serializers.Charfield(source='group.name') #ForiegnKey
    rls = serializers.SerializerMethodField()

    def get_rls(self, row):
        role_obj_list = row.objects.all()
        ret = []
        for item in role_obj_list:
            ret.append({'id': item.id, 'title': item.title})
        return ret

    # 过滤函数
    def get_queryset(self):
        return self.queryset.filter(end_time__gt=timezone.now())

INSTALLED_APPS = (
    ...
    'rest_framework',
)

urlpatterns = [
    ...
    url(r'^api-auth/', include('rest_framework.urls'))
]

REST_FRAMEWORK = {
    # Use Django's standard `django.contrib.auth` permissions,
    # or allow read-only access for unauthenticated users.
    'DEFAULT_PERMISSION_CLASSES': [
        'rest_framework.permissions.DjangoModelPermissionsOrAnonReadOnly'
    ]
}

# http://www.django-rest-framework.org/tutorial/1-serialization/
# 序列化
snippet = Snippet(code='print "hello, world"\n')
snippet.save()
serializer = SnippetSerializer(snippet)
content = JSONRenderer().render(serializer.data)

# 反序列化
from django.utils.six import BytesIO
stream = BytesIO(content)
data = JSONParser().parse(stream)
serializer = SnippetSerializer(data=data)
serializer.is_valid()
# True
serializer.validated_data
# OrderedDict([('title', ''), ('code', 'print "hello, world"\n'), ('linenos', False), ('language', 'python'), ('style', 'friendly')])
serializer.save()
# <Snippet: Snippet object>

 class IndexSerializers(serializers.HyperlinkedModelSerializer):
        name = serializers.ReadOnlyField(source='goods.name')    # 增加外健的字段
        price = serializers.ReadOnlyField(source='goods.price')  # 添加外健的字段 

        class Meta:
            model = Index
            fields = ('goods', 'start_at', 'end_at', 'name', 'price')

html = '''
<div>
    <ul>
         <li class="item-0">first item</li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
         <li class="item-1 active"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a></li>
     </ul>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html) # 初始化
print(doc('li'))
doc1 = pq(url='http://baidu.com') # url初始化
print(doc1('title')
doc2 = pq(filename='demo.html') # 文件初始化
print(doc2('title')

from pyquery import PyQuery as pq
doc = pq(html)
items = doc('.list')
print(type(items))
print(items)
lis = items.find('li') # 查找节点的所有子孙节点
print(type(lis))
print(lis)

lis1 = items.children('.active') # 查找子节点
print(type(lis1))
print(lis1)

lis2 = items.parent('.active') # 查找父节点
print(type(lis2))
print(lis2)

lis3 = items.parents('.active') # 查找祖先节点
print(type(lis3))
print(lis3)

lis4 = items.siblings('.active') # 查找兄弟节点
print(type(lis4))
print(lis4)

from pyquery import PyQuery as pq
doc = pq(html)
li = doc('.item-0.active')
print(li)
print(str(li))

lis = doc('li').items()
print(type(lis))
for li in lis:
    print(li, type(li))

html = '''
<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
a = doc('.item-0.active a')
print(a, type(a))
print(a.attr('href')) # 等同于print(a.attr.href)，如果有多个结果时，需要遍历

html = '''
<div class="wrap">
    Hello, World
    <p>This is a paragraph.</p>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
wrap = doc('.wrap')
print(wrap.text())
wrap.find('p').remove()
print(wrap.text())

html = '''
<div class="wrap">
    <div id="container">
        <ul class="list">
             <li class="item-0">first item</li>
             <li class="item-1"><a href="link2.html">second item</a></li>
             <li class="item-0 active"><a href="link3.html"><span class="bold">third item</span></a></li>
             <li class="item-1 active"><a href="link4.html">fourth item</a></li>
             <li class="item-0"><a href="link5.html">fifth item</a></li>
         </ul>
     </div>
 </div>
'''
from pyquery import PyQuery as pq
doc = pq(html)
li = doc('li:first-child') # 第一个 li 节点
print(li)
li = doc('li:last-child') # 最后一个 li 节点
print(li)
li = doc('li:nth-child(2)') # 第二个 li 节点
print(li)
li = doc('li:gt(2)') # 第三个 li 之后的 li 节点
print(li)
li = doc('li:nth-child(2n)') # 偶数位置的 li 节点
print(li)
li = doc('li:contains(second)') # 包含 second 文本的 li 节点
print(li)

from lxml import etree
text = '''
<div>
    <ul>
         <li class="item-0"><a href="link1.html">first item</a></li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-inactive"><a href="link3.html">third item</a></li>
         <li class="item-1"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a>
         <li class="li li-first"><a href="link.html">first item</a></li>
     </ul>
 </div>
'''
html = etree.HTML(text) #能自动闭合标签
result = etree.tostring(html) # 转化为字符串
print(result.decode('utf-8'))
print(html)
ret = html.xpath('//li')
print(ret)
print(ret[0])
text = html.xpath('//ul//a//text()') # text()获取文本
print(text)
href = html.xpath('//li/a/@href') # @href属性获取
print(href)
ret1 = html.xpath('//li[contains(@class, "li")]/a/text()') # 属性多值匹配用contains()
print(ret1)
ret2= html.xpath('//li[contains(@class, "li") and @name="item"]/a/text()') # 多属性匹配用and连接
print(ret2)

from lxml import etree

text = '''
<div>
    <ul>
         <li class="item-0"><a href="link1.html">first item</a></li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-inactive"><a href="link3.html">third item</a></li>
         <li class="item-1"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a>
     </ul>
 </div>
'''
html = etree.HTML(text)
# 选取了第一个 li 节点，中括号中传入数字1即可，注意这里和代码中不同，序号是以 1 开头的，不是 0 开头的。
result = html.xpath('//li[1]/a/text()')
print(result)
# 选取了最后一个 li 节点，中括号中传入 last() 即可，返回的便是最后一个 li 节点。
result = html.xpath('//li[last()]/a/text()')
print(result)
# 选取了位置小于 3 的 li 节点，也就是位置序号为 1 和 2 的节点，得到的结果就是前 2 个 li 节点。
result = html.xpath('//li[position()<3]/a/text()')
print(result)
# 选取了倒数第三个 li 节点，中括号中传入 last()-2即可，因为 last() 是最后一个，所以 last()-2 就是倒数第三个。
result = html.xpath('//li[last()-2]/a/text()')
print(result)

from lxml import etree

text = '''
<div>
    <ul>
         <li class="item-0"><a href="link1.html"><span>first item</span></a></li>
         <li class="item-1"><a href="link2.html">second item</a></li>
         <li class="item-inactive"><a href="link3.html">third item</a></li>
         <li class="item-1"><a href="link4.html">fourth item</a></li>
         <li class="item-0"><a href="link5.html">fifth item</a>
     </ul>
 </div>
'''
html = etree.HTML(text)
# 调用了 ancestor 轴，可以获取所有祖先节点，其后需要跟两个冒号，然后是节点的选择器，这里我们直接使用了 *，表示匹配所有节点，因此返回结果是第一个 li 节点的所有祖先节点，包括 html，body，div，ul。
result = html.xpath('//li[1]/ancestor::*')
print(result)
# 这次加了限定条件，这次在冒号后面加了 div，这样得到的结果就只有 div 这个祖先节点了。
result = html.xpath('//li[1]/ancestor::div')
print(result)
# 调用了 attribute 轴，可以获取所有属性值，其后跟的选择器还是 *，这代表获取节点的所有属性，返回值就是 li 节点的所有属性值。
result = html.xpath('//li[1]/attribute::*')
print(result)
# 调用了 child 轴，可以获取所有直接子节点，在这里我们又加了限定条件选取 href 属性为 link1.html 的 a 节点。
result = html.xpath('//li[1]/child::a[@href="link1.html"]')
print(result)
# 调用了 descendant 轴，可以获取所有子孙节点，这里我们又加了限定条件获取 span 节点，所以返回的就是只包含 span 节点而没有 a 节点。
result = html.xpath('//li[1]/descendant::span')
print(result)
# 调用了 following 轴，可以获取当前节点之后的所有节点，这里我们虽然使用的是 * 匹配，但又加了索引选择，所以只获取了第二个后续节点。
result = html.xpath('//li[1]/following::*[2]')
print(result)
# 调用了 following-sibling 轴，可以获取当前节点之后的所有同级节点，这里我们使用的是 * 匹配，所以获取了所有后续同级节点。
result = html.xpath('//li[1]/following-sibling::*')
print(result)