A basic “Hello World” API

Download application

Clone the Hello World application from the GitHub repository into a working directory.

     cd ~/Desktop
     git clone -b master https://github.com/himakoppu/helloworld.git 
     cd helloworld

Or, download the Hello World application from Helloworld app. Unzip the file and copy it into a working directory.

    $ cp -r ~/Downloads/helloworld-master ~/Desktop/helloworld
    $ cd ~/Desktop/helloworld

Application Installation

Install initial python dependencies

Jump to 'Install application requirements' if you already have Python 3 and virtualenv on your machine.

For Linux users:

Run below commands, use 'sudo' as required.

    $ sudo apt update
    $ sudo apt install python3-dev python3-pip python3-virtualenv

For Mac users:

• Install Homebrew using Install Homebrew
• Install Python 3

    $ brew install python3
    $ python3 --version
    Python 3.7.5

• Install virtualenv via pip

    $ pip install virtualenv
    $ virtualenv --version
    16.7.7

For Windows users

• Install Python, Django using Django on Windows
• Jump to Enable logging step

Install application requirements

• Create a new python virtual environment.

    $ virtualenv -p python3 helloworld_venv --no-site-packages

• Switch to the virtual environment.

    $ source helloworld_venv/bin/activate

• Install all application requirements.

    $ pip install -r requirements.txt

• Confirm requirements are installed correctly.

    $ pip list | grep Django
    Django     3.0.8

Enable logging

By default, Hello World application logs of INFO level and higher will be sent to the console. In order to change the logging level -

• Go to helloworld_project/settings.py.
• Go to LOGGING section, go to loggers key and find the helloworld section.
• Change the level to DEBUG.
• We should see messages like below on the server terminal while accessing the application.
  • 2020-07-12 05:05:19: Received a POST request at URL: http://127.0.0.1:8000/
  • 2020-07-12 05:05:28: Received a GET request at URL: http://127.0.0.1:8000/

Start application

$ python manage.py runserver

Go to http://127.0.0.1:8000 in a browser you should see a Hello, World message.

Using the application from command line

• Open a new terminal and try out the below examples
• Example GET calls

    $ curl http://127.0.0.1:8000
    Hello, World
    
    $ curl http://127.0.0.1:8000 -H "Accept:"
    <p>Hello, World</p>
    
    $ curl http://127.0.0.1:8000 -H "Accept: application/json"
    {"message": "Hello, World"}

• Example POST calls

    $ curl http://127.0.0.1:8000 -d '{"username":"xyz"}'
    Post successful!
    
    $ curl http://127.0.0.1:8000 -d ''
    {"error": "Data cannot be empty"}

Testing

• Open a new terminal

    $ cd ~/Desktop/helloworld
    $ source helloworld_venv/bin/activate

Note: Unit tests mock the API requests to the server, so they don't need the server to be running. We can stop the server using Ctrl+C on the server terminal and continue to execute unit tests in the same terminal.

• Execute unit tests

    $ python manage.py test
    Creating test database for alias 'default'...
    System check identified no issues (0 silenced).
    Bad Request: /
    ...Bad Request: /
    ..
    ----------------------------------------------------------------------
    Ran 5 tests in 0.012s
    
    OK
    Destroying test database for alias 'default'...