preface

Over the past few years, I have been struggling in the it industry. Along the way, many have summarized some high-frequency interviews in the python industry. I see most of the new blood in the industry, and I still have all kinds of difficult questions for the answers to all kinds of interview questions or collection

Therefore, I developed an interview dictionary myself, hoping to help everyone, and also hope that more Python newcomers can really join the industry, so that Python fire does not just stay in advertising.

Wechat applet search: Python interview dictionary

Or follow the original personal blog: https://lienze.tech

You can also focus on WeChat official account and send all kinds of interesting technical articles at random: Python programming learning.

route

Modern web applications use meaningful URL s, which helps users remember. Web pages will be more favored by users and improve the return rate

Use the route() decorator to bind functions to URL s

@app.route('/path/<int:uid>',methods=["GET"],endpoint="name") 

Dynamic routing

By marking part of the URL as < variable_ Name > you can add variables to the URL. The marked part is passed to the view function as a keyword parameter as a parameter of the view function

By using converter:variable_name, you can optionally add a converter to specify rules for variables, similar to the routing parameters of Django

@app.route('/test/<username>')
def test(username):
    return 'url: %s' % username

converter

Converter type	explain
int	positive integer
float	Accept positive floating point numbers
path	Similar to string, but can contain slashes
uuid	Accept UUID string
string	Strings other than slashes (default)

Route naming

The flash routing system supports the same route naming method as django. The common writing method can be completed by using endpoint in the @ app.route decorator

Note: if the endpoint parameter is not set, the route is named after the function name by default

from flask import redirect
@app.route('/test', endpoint="test")
def test():
  	# Reverse parsing and redirection
    return redirect(url_for("home"))
  	
@app.route('/home', endpoint="home")
def home():
  	return "home"

**url_for * * is used to resolve route names and generate corresponding routes

If the resolved route name has parameters, as shown below, it can be displayed in the URL_ After the for parameter, use the variable length dictionary to pass the dynamic parameters of the connection

from flask import redirect
@app.route('/test', endpoint="test")
def test():
  	# Reverse parsing and redirection
    return redirect(url_for("home",id=1)) # look here
  	
@app.route('/home/<id>', endpoint="home")
def home():
  	return "home"

Request control

You can also control how the view can be accessed by defining the methods parameter on the route decorator

@app.route('/path/<int:uid>',methods=["GET","POST"],endpoint="views")
def views(uid):
  	if request.method == "GET":
		...
    if request.method == "POST":
      	...

Routing essence

The source code of the app.route decorator method is as follows

def route(self, rule, **options):
    def decorator(f):
        endpoint = options.pop("endpoint", None)
        self.add_url_rule(rule, endpoint, f, **options)
        return f

    return decorator

The closure method of the decorator called add_url_rule method is used for routing mapping of views, so after a view is written, you can not only use the decorator, but also directly use this method for routing mapping definition

def views():
		...
app.add_url_rule("/path","name",views, methods=["GET", "POST"])

add_url_rule(rule, endpoint, view_func,
             methods=["GET", "POST"], defaults = {'k': 'v'}, 
             strict_slashes=True,), redirect_to="https://baidu.com"
'''
rule: URL rule
view_func: View function name
endpoint: Route naming
methods: How requests are allowed
strict_slashes: The slash at the end of the route checks for strictness
defaults: Default value, When URL There are no parameters in the function. When the function needs parameters, use defaults = {'k': 'v'}
redirect_to: Direct redirection
strict_slashes: This parameter is used to set whether our route is in strict mode, False Non strict mode, True Strict, the default is strict
'''