LetterCount

LetterCount allows users to query for the number of times the letter 'p' (or 'P') appears in their favorite subreddit in the past 1000 newest posts. Currently only post titles are checked. Post content and comments are ignored. With the application running, you can request a count for your favorite subreddit by making a request to http://127.0.0.1:8000/reddit/<name of subreddit>/, i.e. to count occurrences of 'p' in /r/aww you could navigate to http://127.0.0.1:8000/reddit/aww/ in your browser. Counts are persisted and reused for 15 minutes to reduce request time and reduce the number of requests sent to the Reddit API. After 15 minutes the count will expire and be refreshed on the next request.

Running the application

1. Clone repository: git clone [email protected]:lfowlie/letterCount.git
2. It is probably a good idea to use virtualenv to keep dependencies clean, so install virtualenv: pip install virtualenv
3. If you're using virtualenv, create an environment: virtualenv <path to environment> Note that this project uses python 2.7.10, you can specify a specific instance of python for virtualenv to use with the --python flag
4. Activate the virtual environment you just created: source <path to environment from step 3>/bin/activate
5. Within the top level lettercount folder, install dependencies: pip install -r requirements.txt
6. Run migrations: python manage.py migrate
7. Run it: python manage.py runserver
8. Request a count for your favorite subreddit in browser or via curl: curl http://127.0.0.1:8000/reddit/aww/. Note that if the trailing / is missing, Django will return a redirect to your url with a trailing /.
9. Run unittests with export DJANGO_SETTINGS_MODULE=lettercount.settings; python manage.py test

Future Improvements

• The Reddit API limits history to the past 1000 posts. An improvement over the current approach would be to run a recurring job that pulls down the post history of every subreddit (there are a little over 1 million) every 10 minutes or some other reasonable amount of time. The count could be persisted in the database using the SubredditLetterCount model, allowing us to build a running total over time. This would also require storing a new "last_submission_id" field on this model so we know where to start counting from the next time we pull down post history. This would also speed up response time for users since we wouldn't need to hit the Reddit API during their request.

• Integrate with other APIs. For example we could allow users to count the number of occurrences of 'p' in the 'Pizza' wikipedia article by integrating with their API and allowing users to navigate to /wikipedia/pizza

• Depending on how this data is to be consumed, one improvement could be to create a frontend or change responses to be JSON format.

• Use a cache to speed up repeated requests instead of the database.

• Extend to allow obtaining a count for any letter or even word. This should just be a matter of adding a query parameter to the request to allow the user to request a specific letter or word, and then searching all post titles for that letter or word instead. Note that if we planned on eventually allowing for words to be queried I would probably have picked a different name for the project :)

• Extend to allow checking for occurrences of the letter in the post contents and/or comments.

• Add logging and metrics

• Flesh out unittests and add end-to-end tests