URL shortener service in Python

This is an URL shortener service written using Python / Flask.

Project details:

• Language: Python
• Framework: Flask
• IDE: PyCharm
• Created on Windows 10

Setup

The setup instructions are for Windows OS.

1. Navigate to the directory of the downloaded project
2. Make sure Python is installed (version >= 3.7.4)
3. Open command line from the directory, and run the following commands:

• pip install virtualenv
• python -m virtualenv ./
• pip install -r requirements.txt
• python app.py

Then, open a browser of your choice and go to http://127.0.0.1:7777/.

Endpoints

I. /encode/

• Given a long URL argument as e.g. http://127.0.0.1:7777/encode?url=https://wikipedia.org, it returns a JSON containing a short URL of the form http://127.0.0.1:7777/6M0qc corresponding to the long link provided, or an error message if the conversion could not be performed.

II. /decode/

• Given a short URL argument as e.g. http://127.0.0.1:7777/decode?url=http://127.0.0.1:7777/6M0qc, it returns a JSON containing the corresponding decoded long URL, if it exists, or an error message otherwise.

III. /redirect/

• This endpoints reads in a short_url as e.g. http://127.0.0.1:7777/redirect?url=http://127.0.0.1:7777/6M0qc, then, similarly to the decode endpoint, it finds the corresponding long_url if has already been encoded. Then instead of just returning it, the endpoint will redirect the page to the given long_url.

Algorithm for generating the short URLs

The generator algorithms simply generates a sequence of random characters (lowercase letters + uppercase letters + numbers) with length specified by the num_chars variable, and then creates a string via concatenating the base_url with the encoding. This string will be stored as the encoded URL in two dictionaries (to ensure an average lookup time of O(1))