Flask框架基础3
Posted gaohuayan
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目录
线程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()
通过字典实现threading-local(函数)
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()
面向对象版
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()
通过setattr和getattr实现
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()
每个对象有自己的存储空间(字典)
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()
兼容线程和协程(源码到request中去看,看local的__getattr__,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()
请求上下文
'''
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
'''
蓝图
使用蓝图之中小型系统
目录结构:
-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'
使用蓝图之大型系统
总结:
1 xxx = Blueprint(‘account‘, name,url_prefix=‘/xxx‘) :蓝图URL前缀,表示url的前缀,在该蓝图下所有url都加前缀
2 xxx = Blueprint(‘account‘, name,url_prefix=‘/xxx‘,template_folder=‘tpls‘):给当前蓝图单独使用templates,向上查找,当前找不到,会找总templates
3 蓝图的befort_request,对当前蓝图有效
4 大型项目,可以模拟出类似于django中app的概念
g对象
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
作用:将默认保存的签名cookie中的值 保存到 redis/memcached/file/Mongodb/SQLAlchemy
安装:pip3 install flask-session
使用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()
使用2(推荐使用):
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()
信号
Flask框架中的信号基于blinker,其主要就是让开发者可是在flask请求过程中定制一些用户行为
安装:pip3 install blinker
内置信号:
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
使用信号:
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()
一个流程中的信号触发点(了解):
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
自定义信号(了解):
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()
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