Air Quality

Introduction:

This project provides the ability to view and store basic pollution information on certain locations, using the AirVisual API.

It utilizes nodejs, typescript and postgres and uses multiple libraries in order to achieve intended behavior:

• axios to call third party APIs.
• express to create our own APIs.
• jest to test everything.
• sequelize as an ORM tool.
• pg to access the postgres database.
• toad-scheduler to create cron jobs.

Getting started

Start up the application locally:

1. Create your own postgres database, being mindful of db_name, db_user, db_password, db_host, db_port.

2. Create AirVisual API key using this portal.

3. Run the following commands:

npm install //To install all required packages
npm build //To transpile all typescript files into .js
npm start //To start the server
npm db:migrate //To create the table schema in the database

Make sure to include the environment variables in a .env file. This file would look something like this:

DB_NAME=<DB_NAME>
DB_USER=<DB_USER>
DB_PASSWORD=<DB_PASSWORD>
DB_HOST=<DB_HOST>
DB_PORT=<DB_PORT>

TEST_DB_NAME=<TEST_DB_NAME>
TEST_DB_USER=<TEST_DB_USER>
TEST_DB_PASSWORD=<TEST_DB_PASSWORD>
TEST_DB_HOST=<TEST_DB_HOST>
TEST_DB_PORT=<TEST_DB_PORT>

AIRVISUAL_API_KEY=<AIRVISUAL_API_KEY>
AIRVISUAL_HOST=<AIRVISUAL_HOST>

PORT=<PORT>

API

- To fetch air pollution info for nearest city

GET /pollution_by_coordinates?lat=<LATITUDE>&lon=<LONGITUDE>

Response: {
    "results": {
        "pollution": {
            "ts": <STRING>
            "aqicn": <INTEGER>
            "aqius": <INTEGER>
            "maincn": <STRING>
            "mainus": <STRING>
        }
    }
}

GET /most_polluted_by_city?city=<CITY>

Response: {
    "results": {
        "timestamp": <STRING>
    }
}

Jobs

- In order to retrieve pollution information and log them in our DB we can run a cronjob dedicated for it which runs every minute once it is started up.

• Retrieve and fill "Paris" data:

npm run job:fillDb runFillParisPollutionJob

Tests

You can run either:

• npm run test
• npm run test:watch To run tests in watch mode