Flask Routing and Views Lab

Learning Goals

• Build and run a Flask application on your computer.
• Manipulate and test the structure of a request object.

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Key Vocab

• Web Framework: software that is designed to support the development of web applications. Web frameworks provide built-in tools for generating web servers, turning Python objects into HTML, and more.
• Extension: a package or module that adds functionality to a Flask application that it does not have by default.
• Request: an attempt by one machine to contact another over the internet.
• Client: an application or machine that accesses services being provided by a server through the internet.
• Web Server: a combination of software and hardware that uses Hypertext Transfer Protocol (HTTP) and other protocols to respond to requests made over the internet.
• Web Server Gateway Interface (WSGI): an interface between web servers and applications.
• Template Engine: software that takes in strings with tokenized values, replacing the tokens with their values as output in a web browser.

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Instructions

This is a test-driven lab. Run pipenv install to create your virtual environment and pipenv shell to enter the virtual environment. Then enter the server/ directory and run pytest -x to run your tests. Use these instructions and pytest's error messages to complete your work in the server/ directory. If you prefer working in a Flask environment to running your application as a script, remember to configure it with the following commands from the server/ directory:

$ export FLASK_APP=app.py
$ export FLASK_RUN_PORT=5555

Instructions begin here:

• Design a Flask application that carries out basic Python functions using routing and views.
• Your index() view should be routed to at the base URL with /. It should Contain an h1 element that contains the title of this application, "Python Operations with Flask Routing and Views".
• A print_string view should take one parameter, a string. It should print the string in the console and display it in the web browser. Its URL should be of the format /print/parameter.
• A count() view should take one parameter, an integer. It should display all numbers in the range of that parameter on separate lines. Its URL should be of the format /count/parameter.
• A math() view should take three parameters: num1, operation, and num2. It must perform the appropriate operation on the two numbers in the order that they are presented. The included operations should be: +, -, *, div (/ would change the URL path), and %. Its URL should be of the format /math/<num1>/<operation>/<num2>.

Once all of your tests are passing, commit and push your work using git to submit.

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Resources

• A Minimal Application - Flask
• Routing - Flask
• Chapter 2. Basic Application Structure - Flask Web Development, 2nd Edition