Now that I can use python, I want to output it on the Web!

After all, when I got to know python, I thought I had to output it somehow, and when I was looking for a python web framework, I came up with Flask and django.

It seems that there are many other things.

Bottle
Django
Flask
Pyramid
Plone

Reference: The hottest Python in 2016! Thorough comparison of three web frameworks http://www.sejuku.net/blog/3713#Python

If you make a mistake at the time of building the environment, you will lose your motivation at once, so I would like to try "Flask", which seems to be relatively easy to introduce.

Environmental setting

CentOS 7

Environment

** Install virtualenv **

Common to python2.7 series and 3.5 series

easy_install virtualenv

You can also use pip

# pip3 install virtualenv

Next, use Flask to create a directory to display the page.

# mkdir test
# cd test

Next, build an environment called env with virtualenv

# virtualenv env

Then activate this environment.

# . env/bin/activate

Flask installation

# easy_install Flask

By the way, it can also be installed with pip.

# pip install flask

Output python file to web

Create hello.py and make the directory structure as shown below.

test ┣ env ┗ hello.py

#hello.py

from flask import Flask
app = Flask(__name__)

@app.route('/')
def hello_world():
    return "Hello World!"

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

Do this.

# python hello.py
 * Running on http://localhost:5000/ (Press CTRL+C to quit)

Check directly from your local web browser. Enter ttp: // localhost: 5000 / or ttp: //127.0.0.1:5000/ in the address bar to open it.

Load HTML file as Templates and output

If the above is successful, I would like to continue loading the "HTML" file.

test ┣ env ┣ templates ┃　┗ world.html ┗ hello.py

Build a directory like the one above.

Prepare the HTML to be loaded this time.

#world.html

<!doctype html>
<title>templates Hello World</title>
<h1>TEMPLATES Hello World</h1>

To load world.html, have hello.py import render_template to load the templates directory.

#hello.py

from flask import Flask,render_template　　#<-- render_Load template
app = Flask(__name__)

@app.route('/')
def hello():
    return render_template('hello.html')

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

Try to create a lower directory with Flask

By tweaking the @ app.route ('/') part of hello.py earlier, you can make it behave as if there is a lower directory. I will actually try it.

#hello.py

from flask import Flask,render_template 
app = Flask(__name__)

@app.route('/world/')　　#<--Load as a virtual world directory
def hello():
    return render_template('hello.html')

if __name__ == '__main__':
#    app.debug = True
    app.run(host='0.0.0.0')

In the above, @ app.route ('/') is changed to @ app.route ('/ world /').

Let's change the HTML so that you can see that it has also changed.

#world.html

<!doctype html>
<title>templates Hello World</title>
 <h1>WORLD Hello World</h1>

I will try it.

# python hello.py
 * Running on http://localhost:5000/ (Press CTRL+C to quit)

At ttp: //127.0.0.1:5000/, it will be Not Found and will not be displayed.

It will be displayed at ttp: //127.0.0.1:5000/world/.

By the way, if you leave it as it is, you can only see it locally on the server.

Since it is on the Web, it is meaningless if it can only be seen on the server local PC. Tweak hello.py a little. Modify the last code, app.run ().

    app.run()

    app.run(host='0.0.0.0')

Now you can access it from other PCs. Of course, it's a matter of course, but please keep port 5000 on the firewall open.

My blunder

When I created "hello.py", I thought it would be fine, so I named it "flask.py".

I'm using this name elsewhere, so I get an error saying that flask can't be imported.

# python flask.py
Traceback (most recent call last):
  File "flask.py", line 1, in <module>
    from flask import Flask
  File "/root/test/flask.py", line 1, in <module>
    from flask import Flask
ImportError: cannot import name 'Flask'

It was a coincidence, but I learned one thing.

The first artificial intelligence. Challenge web output with python. ~ Flask introduction