njdart/hello-flask.min.py

## hello-flask.min.py
from flask import Flask
app = Flask(__name__)

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

@app.route('/about')
def about():
    a = 5
    b = 16
    return """
    <html>
      <head>
        <title>Hello World - About</title>
      </head>
      <body>
        <h1>About</h1>
        <p>This is a simple HTML about page.</p>
        <h2>Some simple math</h2>
        <pre>{a} + {b} = {add}</pre>
        <pre>{a} - {b} = {sub}</pre>
        <pre>{a} * {b} = {mul}</pre>
        <pre>{a} / {b} = {div}</pre>
      </body>
    </html>
    """.format(a=a, b=b, add=a+b, sub=a-b, mul=a*b, div=a/b)

app.run()

## hello-flask.py
# A hello world flask example.
# DO NOT NAME THIS FILE "flask.py". You will get the following error:
#   cannot import name 'Flask' from partially initialized module 'flask'
#
# Also, don't forget to pip install flask
#
from flask import Flask

# we define a name (variable) called app that will contain your "web server" application. The Flask(..) part is how
# we start using the flask library. This creates a flask object (we haven't covered objects/classes) that lets us
# control the web server and tell it how to respond to requests (think back to the API lesson)
#
# For more info on Python Classes, See https://docs.python.org/3/tutorial/classes.html
# For more info on how to use flask, See https://flask.palletsprojects.com/en/1.1.x/
app = Flask(__name__)

# We define a function called "hello_world". This should look familiar to you. The @app.route('/') above the function
# is new to us. This is an annotation that tells our app (our flask web server) that requests for '/' should call
# the "hello_world" function (we call this routing) to create the response
#
# We use '/' here, but you can replace it with other strings, such as '/hello'. Routes usually start with a '/'
@app.route('/')
def hello_world():
    return 'Hello, World!'

# Python allows us to have multi-line strings if we start and end our strings with three quote marks (eg ''' or """)
# We can still call .format() on these strings as we saw in earlier lessons.
# See https://docs.python.org/3.8/library/string.html#format-examples for some advanced .format help
@app.route('/about')
def about():
    a = 5
    b = 16
    return """
    <html>
      <head>
        <title>Hello World - About</title>
      </head>
      <body>
        <h1>About</h1>
        <p>This is a simple HTML about page.</p>
        <h2>Some simple math</h2>
        <pre>{a} + {b} = {add}</pre>
        <pre>{a} - {b} = {sub}</pre>
        <pre>{a} * {b} = {mul}</pre>
        <pre>{a} / {b} = {div}</pre>
      </body>
    </html>
    """.format(a=a, b=b, add=a+b, sub=a-b, mul=a*b, div=a/b)

# If you look at the official "flask getting started" guide, they do not include the following and instead use some
# "magic" to start the flask web server. Instead you can call app.run() to start it.
app.run()

# When you start this program "with python hello-flask.py", you should see the follwing output
## * Serving Flask app "hello-flask" (lazy loading)
## * Environment: production
##   WARNING: This is a development server. Do not use it in a production deployment.
##   Use a production WSGI server instead.
## * Debug mode: off
## * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
#
# When you visit http://127.0.0.1:5000/ in your browser (or http://127.0.0.1:5000/about to see the about page),
# you should see flask "logs" the request and response in the console:
## 127.0.0.1 - - [12/Mar/2020 13:22:12] "GET / HTTP/1.1" 200 -
## 127.0.0.1 - - [12/Mar/2020 13:22:15] "GET /about HTTP/1.1" 200 -
#
# This tells you a bunch of things:
# 127.0.0.1 - - [12/Mar/2020 13:22:12] "GET /about HTTP/1.1" 200 -
# Who       - - When                    How What             Response
#
# Who: the "identifier" of the person making the request. In this case, 127.0.0.1 (or "localhost") means the same
#      machine as the web server is running on
#
# When: the date and time of the request
#
# How: How is the request made. This can be a couple of things, it relates to what action the request is trying to
#      achieve. A "GET" is getting something, there are other options here to make changes ("POST", "PUT"), to get
#      some information about something ("OPTIONS", "HEAD"), or to delete something ("DELETE"). These are called
#      HTTP verbs (or methods). See See https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods
#
# What: What the request was for. This is the path (or route) that can be a string you defined in your @app.route(..)
#       It could also be a path that isn't defined, for example if you mis-spelled a link, that will get logged here
#
# Response: The HTTP status code (remember back to the lession on APIs) that the web server responsed with.
#           See https://developer.mozilla.org/en-US/docs/Web/HTTP/Status
#           For a short overfiew, see https://twitter.com/stevelosh/status/372740571749572610
#

## hello-forms.py
#
# A simple example that asks the user on the about page for their name, then echoes the name back to them
#

# We have to include the "request" object from flask. This lets us get information
# about the incoming request (such as the who, what, how, etc we saw earlier)
from flask import Flask, request
app = Flask(__name__)

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

# We can get information from the user by adding a "<form></form>" element
# This has an action (a path or route to send data to), and a method (how to
# send the data). We can then define another flask path (or route) to do
# something with this data
@app.route('/about')
def about():
    a = 5
    b = 16
    return """
    <html>
      <head>
        <title>Hello World - About</title>
      </head>
      <body>
        <h1>About</h1>
        <p>This is a simple HTML about page.</p>
        <h2>Some simple math</h2>
        <pre>{a} + {b} = {add}</pre>
        <pre>{a} - {b} = {sub}</pre>
        <pre>{a} * {b} = {mul}</pre>
        <pre>{a} / {b} = {div}</pre>

        <hr />

        <form action="/form" method="post">
          <a>Please enter your name:</a>
          <input type="text" name="name" id="name">
          <input type="submit" value="Greet Me">
        </form>
      </body>
    </html>
    """.format(a=a, b=b, add=a+b, sub=a-b, mul=a*b, div=a/b)

# This route is where the above form will send the data. Note that the
# path and method match the <form> and @app.route()
@app.route('/form', methods=["POST"])
def formSubmit():
    print(request.form)
    name = request.form["name"]
    print(name)
    return """
    <html>
      <head>
        <title>Hello {name}</title>
      </head>
      <body>
        <h1>Hello {name}</h1>
        <p>Your name is</p>
        <pre>{name}</pre>
        <hr />

        <a href="/about">Go Back</a>
      </body>
    </html>
    """.format(name=name)

app.run()
	from flask import Flask
	app = Flask(__name__)

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

	@app.route('/about')
	def about():
	a = 5
	b = 16
	return """
	<html>
	<head>
	<title>Hello World - About</title>
	</head>
	<body>
	<h1>About</h1>
	<p>This is a simple HTML about page.</p>
	<h2>Some simple math</h2>
	<pre>{a} + {b} = {add}</pre>
	<pre>{a} - {b} = {sub}</pre>
	<pre>{a} * {b} = {mul}</pre>
	<pre>{a} / {b} = {div}</pre>
	</body>
	</html>
	""".format(a=a, b=b, add=a+b, sub=a-b, mul=a*b, div=a/b)

	app.run()
	# A hello world flask example.
	# DO NOT NAME THIS FILE "flask.py". You will get the following error:
	# cannot import name 'Flask' from partially initialized module 'flask'
	#
	# Also, don't forget to pip install flask
	#
	from flask import Flask

	# we define a name (variable) called app that will contain your "web server" application. The Flask(..) part is how
	# we start using the flask library. This creates a flask object (we haven't covered objects/classes) that lets us
	# control the web server and tell it how to respond to requests (think back to the API lesson)
	#
	# For more info on Python Classes, See https://docs.python.org/3/tutorial/classes.html
	# For more info on how to use flask, See https://flask.palletsprojects.com/en/1.1.x/
	app = Flask(__name__)

	# We define a function called "hello_world". This should look familiar to you. The @app.route('/') above the function
	# is new to us. This is an annotation that tells our app (our flask web server) that requests for '/' should call
	# the "hello_world" function (we call this routing) to create the response
	#
	# We use '/' here, but you can replace it with other strings, such as '/hello'. Routes usually start with a '/'
	@app.route('/')
	def hello_world():
	return 'Hello, World!'

	# Python allows us to have multi-line strings if we start and end our strings with three quote marks (eg ''' or """)
	# We can still call .format() on these strings as we saw in earlier lessons.
	# See https://docs.python.org/3.8/library/string.html#format-examples for some advanced .format help
	@app.route('/about')
	def about():
	a = 5
	b = 16
	return """
	<html>
	<head>
	<title>Hello World - About</title>
	</head>
	<body>
	<h1>About</h1>
	<p>This is a simple HTML about page.</p>
	<h2>Some simple math</h2>
	<pre>{a} + {b} = {add}</pre>
	<pre>{a} - {b} = {sub}</pre>
	<pre>{a} * {b} = {mul}</pre>
	<pre>{a} / {b} = {div}</pre>
	</body>
	</html>
	""".format(a=a, b=b, add=a+b, sub=a-b, mul=a*b, div=a/b)

	# If you look at the official "flask getting started" guide, they do not include the following and instead use some
	# "magic" to start the flask web server. Instead you can call app.run() to start it.
	app.run()

	# When you start this program "with python hello-flask.py", you should see the follwing output
	## * Serving Flask app "hello-flask" (lazy loading)
	## * Environment: production
	## WARNING: This is a development server. Do not use it in a production deployment.
	## Use a production WSGI server instead.
	## * Debug mode: off
	## * Running on http://127.0.0.1:5000/ (Press CTRL+C to quit)
	#
	# When you visit http://127.0.0.1:5000/ in your browser (or http://127.0.0.1:5000/about to see the about page),
	# you should see flask "logs" the request and response in the console:
	## 127.0.0.1 - - [12/Mar/2020 13:22:12] "GET / HTTP/1.1" 200 -
	## 127.0.0.1 - - [12/Mar/2020 13:22:15] "GET /about HTTP/1.1" 200 -
	#
	# This tells you a bunch of things:
	# 127.0.0.1 - - [12/Mar/2020 13:22:12] "GET /about HTTP/1.1" 200 -
	# Who - - When How What Response
	#
	# Who: the "identifier" of the person making the request. In this case, 127.0.0.1 (or "localhost") means the same
	# machine as the web server is running on
	#
	# When: the date and time of the request
	#
	# How: How is the request made. This can be a couple of things, it relates to what action the request is trying to
	# achieve. A "GET" is getting something, there are other options here to make changes ("POST", "PUT"), to get
	# some information about something ("OPTIONS", "HEAD"), or to delete something ("DELETE"). These are called
	# HTTP verbs (or methods). See See https://developer.mozilla.org/en-US/docs/Web/HTTP/Methods
	#
	# What: What the request was for. This is the path (or route) that can be a string you defined in your @app.route(..)
	# It could also be a path that isn't defined, for example if you mis-spelled a link, that will get logged here
	#
	# Response: The HTTP status code (remember back to the lession on APIs) that the web server responsed with.
	# See https://developer.mozilla.org/en-US/docs/Web/HTTP/Status
	# For a short overfiew, see https://twitter.com/stevelosh/status/372740571749572610
	#
	#
	# A simple example that asks the user on the about page for their name, then echoes the name back to them
	#

	# We have to include the "request" object from flask. This lets us get information
	# about the incoming request (such as the who, what, how, etc we saw earlier)
	from flask import Flask, request
	app = Flask(__name__)

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

	# We can get information from the user by adding a "<form></form>" element
	# This has an action (a path or route to send data to), and a method (how to
	# send the data). We can then define another flask path (or route) to do
	# something with this data
	@app.route('/about')
	def about():
	a = 5
	b = 16
	return """
	<html>
	<head>
	<title>Hello World - About</title>
	</head>
	<body>
	<h1>About</h1>
	<p>This is a simple HTML about page.</p>
	<h2>Some simple math</h2>
	<pre>{a} + {b} = {add}</pre>
	<pre>{a} - {b} = {sub}</pre>
	<pre>{a} * {b} = {mul}</pre>
	<pre>{a} / {b} = {div}</pre>

	<hr />

	<form action="/form" method="post">
	<a>Please enter your name:</a>
	<input type="text" name="name" id="name">
	<input type="submit" value="Greet Me">
	</form>
	</body>
	</html>
	""".format(a=a, b=b, add=a+b, sub=a-b, mul=a*b, div=a/b)

	# This route is where the above form will send the data. Note that the
	# path and method match the <form> and @app.route()
	@app.route('/form', methods=["POST"])
	def formSubmit():
	print(request.form)
	name = request.form["name"]
	print(name)
	return """
	<html>
	<head>
	<title>Hello {name}</title>
	</head>
	<body>
	<h1>Hello {name}</h1>
	<p>Your name is</p>
	<pre>{name}</pre>
	<hr />

	<a href="/about">Go Back</a>
	</body>
	</html>
	""".format(name=name)

	app.run()