First meet flask

1.Flask Introduce

Flask It's lightweight Web Development framework , Than Django It's a lot lighter
Flask The core is Werkzeug( Routing module ),Jinja2 template engine , To realize other functions, you need to install and expand
Flask Though light , But it has strong expansion ability , Rely on extensions to add functionality

Flask Official address

2. Build a virtual environment

First step

The second step

The third step

Step four

2.1 Advance and retreat virtual environment

Exit virtual environment

First step ： Enter the virtual environment folder

The second step ： Carry out orders , And exit venv file

Enter the virtual environment
First step : Get into venv Under the document scripts Folder

The second step ： perform

The third step ： sign out venv file

3. install Flask

Import the installation files in the root directory

pip install -r  file name .txt

4. Realization Flask

4.1 Realization Flask Get started with Applications

Created in the root directory app.py file

 First step ： Instantiation Flask
from flask import Flask
#  Instantiation flask
# __name__  Current package name 
app = Flask(__name__)

 The second step ： Configure function routing 
#  Configure the routing 
@app.route('/hello')
def hello():
    return "<h1> ha-ha 12345</h1>"
    
 The third step ： start-up flask
if __name__ == '__main__':
    app.run()

4.2 Factory mode

Factory mode : Responsible for creating other types of objects , The user calls this method with parameters , The factory returns to the client

4.2.1 Example of factory model

#  Write an interface class 
class Animal():
    def do_say(self):
        pass

class Cat(Animal):
    def do_say(self):
        print('miao miao')

class Dog(Animal):
    def do_say(self):
        print('wang wang')

class Forest():
    def sav(self,animal_type):
        return eval(animal_type)().do_say()

if __name__ == '__main__':
    a = input(' Please enter the animal type :Cat or Dog:')
    print('111',a)
    Forest().sav(a)

4.2.2 Factory mode

encapsulation APP : establish py file

from flask import Flask

def create_app():
	flask_app = Flask(__name__)
	print(' Call me ')
	return flask_app

Create a file and call

View routes — Run on the command line : flask routes

 First step ： Import the encapsulated function 
from create_app import create_app
from flask import url_for

 The second step ： call 
app = create_app()

# endpoint  Used for route reverse generation 
#method  Usage method 
@app.route('/hello',methods=['get','post'],endpoint='aaa')
def hello():
    return 'hello'

# url_for  Reverse query 
@app.route('/path')
def get_path():
    url = url_for('aaa')
    print(url)
    return url
    
 The third step ： start-up 
if __name__ == '__main__':
    app.run()

4.3 Flask To configure

1. Load... From the configuration object
2. Load from the configuration file
3. Load from the environment variable

4.3.1 Load... From the configuration object

First step : establish py file

class DefaultConfig:
    #  Property name   It has to be all in capitals 
    NAME = "haha"
    #  Automatically refresh 
    DEBUG = True

The second step ： call

from flask import Flask
from settings.config import DefaultConfig
#  Instantiation flask
# __name__  Current package name 
app = Flask(__name__)
app.config.from_object(DefaultConfig)  #  Load configuration from object 
print('1111', app.config)

# "D:\python\p7\pwd.py"
#  Configure the routing 
@app.route('/hello')
def hello():
    return "<h1> ha-ha 12345</h1>"

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

4.3.2 Load from the configuration file

First step : establish py file

#  Through the configuration file 

AGE = 18

The second step ： call

from flask import Flask

#  Instantiation flask
# __name__  Current package name 
app = Flask(__name__)
app.config.from_pyfile('setting.py') #  Load configuration from file 

print('1111', app.config)

# "D:\python\p7\pwd.py"
#  Configure the routing 
@app.route('/hello')
def hello():
    return "<h1> ha-ha 12345</h1>"

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

4.3.3 Call... From the environment variable

First step ： Create files from different directories

PASSWORD = 123456

The second step ： Configure environment variables

from flask import Flask

#  Instantiation flask
# __name__  Current package name 
app = Flask(__name__)
app.config.from_envvar('pwd',silent=True) #  Configure from environment variables 
print('1111', app.config)

# "D:\python\p7\pwd.py"
#  Configure the routing 
@app.route('/hello')
def hello():
    return "<h1> ha-ha 12345</h1>"

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

The third step ： Configuration environment

4.4 Starting mode

1. app.run()
2. flask.run()
3. Configure pepper

Method 1 ：

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

Method 2 ：

 perform ：flask fun  command 

Method 3 :