Flask is a micro framework developed based on Python and relying on jinja2 templates and Werkzeug WSGI services. For Werkzeug, it is essentially a Socket server, which is used to receive http requests and preprocess them, and then trigger the Flask framework. Developers are based on the Flask framework. The provided function processes the request accordingly and returns it to the user. If you want to return complex content to the user, you need to use the jinja2 template to process the template, that is: render the template and data, and render the rendered characters. The string is returned to the user's browser.
"Micro" doesn't mean you need to cram your entire web application into a single Python file (though you can), nor does it mean that Flask is lacking in functionality. The "micro" in microframework means that Flask aims to keep the core simple and easy to extend. Flask doesn't make many decisions for you - like what database to use. And those that Flask chooses—such as which template engine to use—are easy to replace. Everything beyond that is up to you. In this way, Flask can work perfectly with you.
By default, Flask doesn't include a database abstraction layer, form validation, or any other functionality that many libraries already do. However, Flask supports extensions to add these features to applications, just as Flask itself does. Numerous extensions provide database integration, form validation, upload handling, various open authentication technologies, and more. Flask may be "tiny", but it's ready for production in demanding environments.
tool
"""
from werkzeug.wrappers import Request, Response
from werkzeug.serving import run_simple
@Request.application
def hello(request):
return Response('Hello World!')
if __name__ == '__main__':
# When the request is called, automatically execute: hello()
run_simple('localhost', 4000, hello)
"""
from werkzeug.wrappers import Request, Response
from werkzeug.serving import run_simple
class Foo(object):
def __call__(self, *args, **kwargs):
return Response('Hello World!')
if __name__ == '__main__':
# When the request is called, automatically execute: hello()
obj = Foo()
run_simple('localhost', 4000, obj)
install flask
pip3 install flask
basic use
"""
pip install flask
pip3 install flask
"""
from flask import Flask
# 1. Instantiate the Flask object
app = Flask('xxxx')
"""
1. Execute app.route('/index') and get the return value xx
2.
@xx
def index():
return 'Hello World'
3. Execute index = xx(index)
Nature:
{
'/index': index
}
"""
@app.route('/index')
def index():
return 'Hello World'
if __name__ == '__main__':
app.run()
1 The use of decorators, the definition of template template template_folder='templates' static_folder='static' The default path is also this template file and static file
2 methods=["GET","POST"]
3 The use of the default session is to store secret_key='****asdasds**' in the encrypted cookie of the browser and write one end of the string
import functools
from flask import Flask,render_template,request,redirect,session
app = Flask('xxxx',template_folder="templates")
app.secret_key = 'as923lrjks9d8fwlkxlduf'
def auth(func):
@functools.wraps(func)
def inner(*args,**kwargs):
user_info = session.get('user_info')
if not user_info:
return redirect('/login')
return func(*args,**kwargs)
return inner
"""
{
/order: inner函数, name: order
/index: inner function, name: index
}
"""
@app.route('/order',methods=['GET'])
@auth
def order():
user_info = session.get('user_info')
if not user_info:
return redirect('/login')
return render_template('index.html')
@app.route('/index',methods=['GET'])
@auth
def index():
return render_template('index.html')
@app.route('/login',methods=['GET','POST'])
def login():
if request.method == "GET":
return render_template('login.html')
else:
user = request.form.get('user')
pwd = request.form.get('pwd')
if user == 'alex' and pwd == '123':
session['user_info'] = user
return redirect('/index')
# return render_template('login.html',msg = "Incorrect username or password",x = 123)
return render_template('login.html',**{'msg':'username or password is incorrect'})
@app.route('/logout',methods=['GET'])
def logout():
del session['user_info']
return redirect('/login')
if __name__ == '__main__':
app.run()
flask preparation stage
app = Flask(__name__)
Instantiate the Flask object
@app.route('/index')
Save the routing rules to the Map class
The run() method is executed, the server side of the socket starts to run, waiting for the user to connect
flask run phase
The entry point of flask's operation is the __call__ method
Then start executing the view function
configure
s1.py
app.config.from_object('settings.TestingConfig')
settings.py
class BaseConfig(object):
DEBUG = False
SESSION_REFRESH_EACH_REQUEST = True
class ProConfig(BaseConfig):
pass
class DevConfig(BaseConfig):
DEBUG = True
class TestingConfig(BaseConfig):
routing system
- Add the essence of routing @app.route('/index') def index(): return "index" def order(): return 'Order' app.add_url_rule('/order', None, order) FBV: @app.route('/index') def index(): if return "index" def order(): return 'Order' app.add_url_rule('/order', None, order) CBV: class X1View(views.MethodView): methods = ['GET','POST'] decorators = [auth, ] def get(self): return 'x1.GET' def post(self): return 'x1.POST' app.add_url_rule('/x1', view_func=X1View.as_view(name='x1')) # name=endpoint
Source code process a. Generate routing relationship [ Rule('index', function), Rule('index', function), Rule('index', function), Rule('index', function), ] b. User request comes - Get user U request and match it - place ctx (the object that encapsulates all data related to the request) to a "special location" c. Execute the view function d. Respond to the function return value to the user e. Remove ctx in "special position".
template file
1 import functools 2 from flask import Flask,render_template,request,redirect,session,Markup 3 4 app = Flask('xxxx',template_folder="templates") 5 app.secret_key = 'as923lrjks9d8fwlkxlduf' 6 7 @app.template_global() 8 def sb(a1,a2): 9 return a1+a2 10 @app.template_filter() 11 def db(a1,a2,a3): 12 return a1+a2+a3 13 def fffff(value): 14 return Markup("<input type='text' value=%s>"%(value)) 15 16 @app.route('/index',methods=['GET']) 17 def index(): 18 context = { 19 'k1': 'v1', 20 'k2': [11, 22, 33], 21 'k3':{ 22 'name': 'oldboy', 23 'age': 56 24 }, 25 'k4': fffff 26 } 27 return render_template('index.html',**context) 28 29 30 if __name__ == '__main__': 31 app.run()
{%extends 'layout.html'%} {%block content%} <h2>index</h2> <div> {%include 'sakula.html'%} </div> <div> {{k4 ('hebe')}} </div> <div> {{k1}} </div> <div>{{k2}}</div> <div> {% for k,v in k3.items()%} {{k}} - {{v}} {%endfor%} </div> <div> {{k3.name}} {{k3['name']}} {{k3.get('name')}} </div> <div> Global function: {{sb(1,2)}} Global function 2: {{1|db(2,3)}} </div> {%endblock%}