Hands-on Flask-03 : Handling Forms and SQL with Flask Web Application

Purpose of the this hands-on training is to give the students introductory knowledge of how to handle forms, how to connect to database and how to use sql within Flask web application on Amazon Linux 2 EC2 instance.

Learning Outcomes

At the end of the this hands-on training, students will be able to;

• install Python and Flask framework on Amazon Linux 2 EC2 instance.

• build a web application with Python Flask framework.

• handle forms using the flask-wtf module.

• configure connection to the sqlite database.

• configure connection to the MySQL database.

• work with a database using the SQL within Flask application.

• use git repo to manage the application versioning.

• run the web application on AWS EC2 instance using the GitHub repo as codebase.

Outline

• Part 1 - Getting to know HTTP methods (GET & POST).

• Part 2 - Install Python and Flask framework Amazon Linux 2 EC2 Instance

• Part 3 - Write a Sample Web Application with forms and database implementation on GitHub Repo

• Part 4 - Run the Sample Web Application on EC2 Instance

Part 1 - Getting to know HTTP methods (GET & POST)

HTTP (Hypertext Transfer Protocol) is a request-response protocol. A client on one side (web browser) asks or requests something from a server and the server on the other side sends a response to that client.

When sending request, the client can send data with using different http methods like GET, POST, PUT, HEAD, DELETE, PATCH, OPTIONS, but the most common ones are GET and POST.

• HTTP GET method request;

  • used to request data from a specified resource.

  • can be cached.

  • remains in the browser history.

  • can be bookmarked

  • should never be used when dealing with sensitive data.

  • has length limitation.

  • only used to request data, not to modify it.

• HTTP POST method request;

  • never cached.

  • does not remain in the browser history.

  • can not be bookmarked

  • can be used when dealing with sensitive data.

  • has no length limitation.

Part 2 - Install Python and Flask framework on Amazon Linux 2 EC2 Instance

• Launch an Amazon EC2 instance using the Amazon Linux 2 AMI with security group allowing SSH (Port 22) and HTTP (Port 80) connections.

• Connect to your instance with SSH.

• Update the installed packages and package cache on your instance.

• Install Python 3 packages.

• Check the python3 version

• Install Python 3 Flask framework.

• Install flask_sqlalchemy.

• Install flask_mysql.

Part 3 - Write a Sample Web Application with forms and database implementation on GitHub Repo

• Create folder named flask-03-handling-forms-and-sql-on-ec2-linux2 within clarusway-python-workshop repo

• Write an application with form handling and save the complete code as app-form-handling.py under hands-on/flask-03-handling-forms-and-sql-on-ec2-linux2 folder.

• Import Flask modules

• Create an object named app

• Create a function named home which uses template file named index.html given under templates folder,

• send your name as template variable, and assign route of no path ('/')

• Write a function named greet which uses template file named greet.html given under templates folder

• and assign to the static route of ('/greet')

• Write a function named login which uses GET and POST methods,

• and template files named login.html and secure.html given under templates folder

• and assign to the static route of ('login')

• Add a statement to run the Flask application which can be reached from any host on port 80.

• Write an application with database implementation using MySQL and save the complete code as app-with-mysql.py under hands-on/flask-03-handling-forms-and-sql-on-ec2-linux2 folder.

• Write a function named find_emails which find emails using keyword from the user table in the db,

• and returns result as tuples (name, email).

• Write a function named insert_email which adds new email to users table the db.

• Write a function named emails which finds email addresses by keyword using GET and POST methods,

• using template files named emails.html given under templates folder

• and assign to the static route of ('/')

• Write a function named add_email which inserts new email to the database using GET and POST methods,

• using template files named add-email.html given under templates folder

• and assign to the static route of ('add')

• Add a statement to run the Flask application which can be reached from any host on port 80.

Part 4 - Run the Hello World App on EC2 Instance

• Download the web application file from GitHub repo.

• Run the form handling web application

• Connect the web application from the web browser and try every page configured

• Connect the web application default / page from the terminal with curl command.

• Connect the web application /greet page with no param from the terminal with curl command.

• Connect the web application /greet page with user=Sergio%20Taco param from the terminal with curl command.

• Connect the web application /login page with GET method from the terminal with curl command.

• Connect the web application /login page with POST method from the terminal with curl command.

• Run the sqlite web application and showcase from the web browser.

• Run the MySQL web application and showcase from the web browser.