Flask frame base 3

Thread threading

from threading import Thread
from threading import local
import time

cxw = local()
def task(arg):
    cxw.value = arg
    time.sleep(2)
    print(cxw.value)
    
for i in range(10):
    t = Thread(target=task, args(i,))
    t.start()

Achieve threading-local (function) by the dictionary

from threading import Thread, get_ident
import time

storage = {}
def set(k, v):
    ident = get_ident()
    if ident in storage:
        storage[ident][k] = v
    else:
        storage[ident] = {k:v}
def get(k):
    ident = get_ident()
    return storage[ident][k]
def task(arg):
    set('val',arg)
    v = get('val')
    print(v)

for i in range(10):
    t = Thread(target=task,args=(i,))
    t.start()

Object-oriented version

from threading import get_ident,Thread
import time
class Local(object):
    storage = {}
    def set(self, k, v):
        ident = get_ident()
        if ident in Local.storage:
            Local.storage[ident][k] = v
        else:
            Local.storage[ident] = {k: v}
    def get(self, k):
        ident = get_ident()
        return Local.storage[ident][k]
obj = Local()
def task(arg):
    obj.set('val',arg) 
    v = obj.get('val')
    print(v)
for i in range(10):
    t = Thread(target=task,args=(i,))
    t.start()

Achieved by setattr and getattr

from threading import get_ident,Thread
import time
class Local(object):
    storage = {}
    def __setattr__(self, k, v):
        ident = get_ident()
        if ident in Local.storage:
            Local.storage[ident][k] = v
        else:
            Local.storage[ident] = {k: v}
    def __getattr__(self, k):
        ident = get_ident()
        return Local.storage[ident][k]
obj = Local()
def task(arg):
    obj.val = arg
    print(obj.val)
for i in range(10):
    t = Thread(target=task,args=(i,))
    t.start()

Each object has its own memory space (dictionary)

from threading import get_ident,Thread
import time
class Local(object):
    def __init__(self):
        object.__setattr__(self,'storage',{})
        self.storage={}
    def __setattr__(self, k, v):
        ident = get_ident()
        if ident in self.storage:
            self.storage[ident][k] = v
        else:
            self.storage[ident] = {k: v}
    def __getattr__(self, k):
        ident = get_ident()
        return self.storage[ident][k]
obj = Local()
def task(arg):
    obj.val = arg
    obj.xxx = arg
    print(obj.val)
for i in range(10):
    t = Thread(target=task,args=(i,))
    t.start()

And coroutine compatible thread (see the source code to the request, the look __getattr local __, setattr)

try:
    from greenlet import getcurrent as get_ident
except Exception as e:
    from threading import get_ident
from threading import Thread
import time
class Local(object):
    def __init__(self):
        object.__setattr__(self,'storage',{})
    def __setattr__(self, k, v):
        ident = get_ident()
        if ident in self.storage:
            self.storage[ident][k] = v
        else:
            self.storage[ident] = {k: v}
    def __getattr__(self, k):
        ident = get_ident()
        return self.storage[ident][k]
obj = Local()
def task(arg):
    obj.val = arg
    obj.xxx = arg
    print(obj.val)
for i in range(10):
    t = Thread(target=task,args=(i,))
    t.start()
   

Request context

'''
全局的变量
_request_ctx_stack = LocalStack()
_app_ctx_stack = LocalStack()
current_app = LocalProxy(_find_app)
#local就是我们的partial(_lookup_req_object, "request")
request = LocalProxy(partial(_lookup_req_object, "request"))
session = LocalProxy(partial(_lookup_req_object, "session"))
g = LocalProxy(partial(_lookup_app_object, "g"))

self.wsgi_app(environ, start_response)源码：
    def wsgi_app(self, environ, start_response):
        #ctx是ResquestContext的对象，里面request
        ctx = self.request_context(environ)
        error = None
        try:
            try:
                #就是ctx放到了Local对象
                ctx.push()
                #所有请求的执行函数的，包括请求扩展，真正的视图函数
                response = self.full_dispatch_request()
            except Exception as e:
                error = e
                response = self.handle_exception(e)
            except:  # noqa: B001
                error = sys.exc_info()[1]
                raise
            # 请求之后的函数
            return response(environ, start_response)
        finally:
            if self.should_ignore_error(error):
                error = None
            ctx.auto_pop(error)
1 ctx = self.request_context(environ) environ,请求相关的，ctx现在是包含request,session的RequestContext的对象
    源码：
        1.1RequestContext(self, environ) self ,是app对象 environ,请求相关的
        1.2 RequestContext在实例化的时候的源码：
        def __init__(self, app, environ, request=None, session=None):
            self.app = app
            if request is None:
                request = app.request_class(environ)
            self.request = request
            self.url_adapter = None
            try:
                self.url_adapter = app.create_url_adapter(self.request)
            except HTTPException as e:
                self.request.routing_exception = e
            self.flashes = None
            self.session = session
            self._implicit_app_ctx_stack = []
            self.preserved = False
            self._after_request_functions = []
        这个RequestContext对象封装了,request 和seesoin

2  ctx.push()这个ctx是RequestContext，那就执行RequestContext.push方法
    2.1RequestContext.push()的源码
        def push(self):
            #_request_ctx_stack是localStack的对象
            #self是ctx,把self也就ctx放入到local对象里面
            _request_ctx_stack.push(self)
            if self.session is None:
                session_interface = self.app.session_interface
                self.session = session_interface.open_session(self.app, self.request)

                if self.session is None:
                    self.session = session_interface.make_null_session(self.app)

            if self.url_adapter is not None:
                self.match_request()
        2.1.1 _request_ctx_stack.push(self)现在的self是ctx
        2.1.2 _request_ctx_stack是LocalStack()的对象
        2.1.3 LocalStack()的push把ctx传过来
        2.1.4 LocalStack()的push方法
            源码：
            #obj是ctx
            def push(self, obj):
                #obj是ctx,requestContext的对象
                rv = getattr(self._local, "stack", None)
                if rv is None:
                    # self._local是Local()的对象
                    # storage[“线程id或者协程id”][stack] = [ctx,]
                    self._local.stack = rv = []
                rv.append(obj)
                return rv

    2的最终也就是ctx.push()他的最终目的：把当前的ctx放入到Local()里面

3  response = self.full_dispatch_request()
    源码:
        def full_dispatch_request(self):
            #这是服务器第一次请求时候执行的函数
            self.try_trigger_before_first_request_functions()
            try:
                request_started.send(self)
                #执行请求之前所有的函数，并且拿到请求之前的返回值
                rv = self.preprocess_request()
                if rv is None:
                    #这个是真正视图函数，如果我的请求之前函数没有返回值才会执行
                    rv = self.dispatch_request()
            except Exception as e:
                rv = self.handle_user_exception(e)
            return self.finalize_request(rv)
    3.1 return self.finalize_request(rv)的源码：
        def finalize_request(self, rv, from_error_handler=False):
            response = self.make_response(rv)
            try:
                #请求之后的函数，after_request
                response = self.process_response(response)
                request_finished.send(self, response=response)
            except Exception:
                if not from_error_handler:
                    raise
                self.logger.exception(
                    "Request finalizing failed with an error while handling an error"
                )
            return response
4 我们的现在已经在2步的时候把我们request已经方法Locald对象中了，我们第三步的任意一个地方
都能使用我们的request,session,拿他是怎么获取的？
    4.1 我们在flask导入request,这个request是一个全局的变量，我们怎么通过request区分我当前的request对象(environ)
     我们发现request是LocalProxy的对象
    4.2 当我们用全局的request.属性的时候，就会去找LocalProxy的对象，但是我们发现里面根本就没有
        那他一定执行LocalProxy对象的__getattr__方法
    4.3 我们现在来看LocalProxy对象的__getattr__方法的源码：
        #name我们要获取属性名
        def __getattr__(self, name):
            if name == "__members__":
                return dir(self._get_current_object())
            #form
            #self._get_current_object()就是ctx里面的request，
            return getattr(self._get_current_object(), name)
        4.3.1 通过反射self._get_current_object()对象，来找我们属性，也就是name
           self._get_current_object()的源码：
                def _get_current_object(self):
                    if not hasattr(self.__local, "__release_local__"):
                        return self.__local()
                    try:
                        #self.__local就实例化传过来的偏函数,
                        return getattr(self.__local, self.__name__)
                    except AttributeError:
                        raise RuntimeError("no object bound to %s" % self.__name__)

           4.3.1.1 return getattr(self.__local, self.__name__)那这里self.__local是谁？
                    def __init__(self, local, name=None):
                          object.__setattr__(self, "_LocalProxy__local", local)
                    self.___local为local
                    这个local为实例化的时候传的
                4.3.1.1.1 这个实例化的时候的操作
                   request = LocalProxy(partial(_lookup_req_object, "request"))
                   4.3.1.1的local就是 partial(_lookup_req_object, "request")的地址
                4.3.1.1.2 _lookup_req_object的源码：
                    #调用的时候 partial(_lookup_req_object, "request")
                    #现在的name就是"request"
                    def _lookup_req_object(name):
                        # top是当前线程的ctx
                        top = _request_ctx_stack.top
                        if top is None:
                            raise RuntimeError(_request_ctx_err_msg)
                        #找top里面的request
                        # ctx找request
                        return getattr(top, name)
                4.3.1.1.2 我们来看这个_request_ctx_stack.top的top方法
                        def top(self):
                            try:
                                return self._local.stack[-1]
                            except (AttributeError, IndexError):
                                return None
                        我们发现这个self._local是Local()对象,这样就把ctx拿到了

'''

blueprint

Use small and medium systems blueprint

Directory Structure:

-flask_pro
    -flask_test
        -__init__.py
        -static
        -templates
        -views
            -order.py
            -user.py
     -manage.py 
        

__init__.py

from flask import  Flask
app=Flask(__name__)
from flask_test.views import user
from flask_test.views import order
app.register_blueprint(user.us)
app.register_blueprint(order.ord)

manage.py

from flask_test import  app
if __name__ == '__main__':
    app.run()

user.py

from flask import Blueprint
us=Blueprint('user',__name__)

@us.route('/login')
def login():
    return 'login'

order.py

from flask import Blueprint
ord=Blueprint('order',__name__)

@ord.route('/test')
def test():
    return 'order test'

Use blueprint of large systems

to sum up:

XXX = the Blueprint. 1 ( 'Account', name , url_prefix = '/ XXX'): Blueprint URL prefixes Prefix indicating the url, in this blueprint are all prefix url

2 xxx = Blueprint ( 'account', name, url_prefix = '/ xxx', template_folder = 'tpls'): to the current blueprint templates used alone, look up the current fails, you will always find templates

3 blueprint befort_request, valid for the current blueprint

4 large projects, can be simulated in the app concept is similar to django

g Object

from flask import Flask,views,session,request,g
app=Flask(__name__)

''''
session 只要设置，在任意请求中都能拿到，无论你拿多少次
flash   一旦设置，可在任意一次请求中获取，但是只能取一次
g     一旦设置，只能在当请求中获取，其它的请求都不能获取

'''

@app.after_request
def test(response):
    print(g.name)
    return response

@app.route("/")
def index():
    g.name = "suv"
    return "ok"

@app.route("/index")
def index1():
    return "ojbk"


if __name__ == '__main__':

    app.run()

flask-session

Role: Save the default values ​​stored signature cookie is to redis / memcached / file / Mongodb / SQLAlchemy

安装：pip3 install flask-session

Use 1:

from flask import Flask,session
from flask_session import RedisSessionInterface
import redis
app = Flask(__name__)
conn=redis.Redis(host='127.0.0.1',port=6379)

#use_signer是否对key签名
#如果use_siginer为False,这表示不需要配置app.secret_key
app.secret_key="aksdhkajs"

app.session_interface=RedisSessionInterface(conn,key_prefix='lqz',
                                            use_signer=True,permanent=False)

'''
之前的session
seesion名字为配置文件中的名字
存
seesion  ->加密-->cookie
取
session -->值  ---->解密

redis的seesion
seesion名字为配置文件中的名字
name=self.key_prefix + session.sid, value=val 是redis里面的键
val存到redis
seesion  -->name
name加前缀--->redis取

'''
@app.route('/')
def hello_world():
    session['name']='lqz'
    return 'Hello World!'

@app.route("/index")
def index():
    print(session['name'])
    return "ok"


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

Use 2 (recommended):

from flask import Flask,session
from redis import Redis
from flask_session import Session
app = Flask(__name__)
app.config['SESSION_TYPE'] = 'redis'
app.config['SESSION_REDIS'] = Redis(host='127.0.0.1',port='6379')
Session(app)

@app.route('/')
def hello_world():
    session['name']='lqz'
    return 'Hello World!'

@app.route("/index")
def index():
    print(session['name'])
    return "ok"


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

signal

Flask framework based on the signal blinker, whose main is to allow developers to customize, but some users behavior flask request process

installation:pip3 install blinker

Built-in signal:

request_started = _signals.signal('request-started')                # 请求到来前执行
request_finished = _signals.signal('request-finished')              # 请求结束后执行
 
before_render_template = _signals.signal('before-render-template')  # 模板渲染前执行
template_rendered = _signals.signal('template-rendered')            # 模板渲染后执行
 
got_request_exception = _signals.signal('got-request-exception')    # 请求执行出现异常时执行
 
request_tearing_down = _signals.signal('request-tearing-down')      # 请求执行完毕后自动执行（无论成功与否）
appcontext_tearing_down = _signals.signal('appcontext-tearing-down')# 应用上下文执行完毕后自动执行（无论成功与否）
 
appcontext_pushed = _signals.signal('appcontext-pushed')            # 应用上下文push时执行
appcontext_popped = _signals.signal('appcontext-popped')            # 应用上下文pop时执行
message_flashed = _signals.signal('message-flashed')                # 调用flask在其中添加数据时，自动触发

Use signals:

from flask import Flask,signals,render_template

app = Flask(__name__)

# 往信号中注册函数
def func(*args,**kwargs):
    print('触发型号',args,kwargs)
signals.request_started.connect(func)

# 触发信号： signals.request_started.send()
@app.before_first_request
def before_first1(*args,**kwargs):
    pass
@app.before_first_request
def before_first2(*args,**kwargs):
    pass

@app.before_request
def before_first3(*args,**kwargs):
    pass

@app.route('/',methods=['GET',"POST"])
def index():
    print('视图')
    return render_template('index.html')


if __name__ == '__main__':
    app.wsgi_app
    app.run()

Signal trigger point in a process (to know):

a. before_first_request
b. 触发 request_started 信号
c. before_request
d. 模板渲染
    渲染前的信号 before_render_template.send(app, template=template, context=context)
        rv = template.render(context) # 模板渲染
    渲染后的信号 template_rendered.send(app, template=template, context=context)
e. after_request
f. session.save_session()
g. 触发 request_finished信号        
    如果上述过程出错：
        触发错误处理信号 got_request_exception.send(self, exception=e)
            
h. 触发信号 request_tearing_down

Custom signal (to know):

from flask import Flask, current_app, flash, render_template
from flask.signals import _signals
app = Flask(import_name=__name__)

# 自定义信号
xxxxx = _signals.signal('xxxxx')
 #必须有一个位置参数，去接收他的发送者，
def func(sender, *args, **kwargs):
    print(sender)
# 自定义信号中注册函数
xxxxx.connect(func)
@app.route("/x")
def index():
    # 触发信号，这里的第一是发送者，第二个参数可选的话，必须是键值对
    xxxxx.send('123123', k1='v1')
    return 'Index' 
 
if __name__ == '__main__':
    app.run()