Description

Technical task as a part of interview process. Full task definition was not provided intentionally.

Task definition

Task is to create a backend API that serves shipment data and provides current weather conditions at user's location.

Use data from assets/seed.csv as initial set of data for this task.

Questions

• What does mean weather for users location?
• Not clear about requirement for status of shipments. Do we need it?
• Why zip codes and locations don't have match in some records in initial dataset?

Solution

Solution is based on given task definition and csv file. The idea was to create multiple entities in relational database, like:

• artcile - article information with price
• carrier - carrier information
• shipment - information about shipments, and potentially with state, if needed
• many-2-many-articles-shipments - csv file describes such model of relations, plus this table contains quantity information for each article in each shipment

Weather information can be fetched on the fly for each location. There are a lot of ways to optimize this process but I chose in-memory cache with TTL. With the given solution it is not problem to connect third party key-value storages like Redis for this cache.

For status of the shipment we can add additional field to our shipment entity and update it based on changes in delivery process. All changes can be stored as events separately in RDMS or NoSQL storage depends on requirements.

Folder Structure

assets/ - static files
config/ - config files for nest.js
prisma/ - prisma related stuff
src/
⋅⋅⋅middleware/ - middleware
⋅⋅⋅pipes/ - nestjs pipes for transformation and validation
⋅⋅⋅resources/ - core components of the nestjs app
test - e2e tests

API specifications

GET /articles/{SKU} - article details for the given SKU, where SKU is the Stock Keeping Unit of the article
POST /articles - create a new article

GET /carriers - list of supported carriers

GET /weather/{ZIP} - weather details for the given location as is from external service, ZIP is the zip code of location

GET /shipments/{TRACKING_NUMBER} - all shipment details with (if available) the current weather information about destination location, TRACKING_NUMBER is a tracking number POST /shipments - create a new shipment

Installation

$ npm install

Running the app

# development
$ npm run start

# watch mode
$ npm run start:dev

# production mode
$ npm run start:prod

Test

# unit tests
$ npm run test

# e2e tests
$ npm run test:e2e

# test coverage
$ npm run test:cov

Database

This project uses Prisma library to interact with databases and Postgres as database.

Do the following to enable database:

1. create .env file in the root folder:

DATABASE_URL=<put here URI to your postgres database in the following format "postgresql://postgres:@localhost:5432/postgres">

2. run npx prisma migrate dev to create a database and seed initial data

Weather information

This app uses free plan of OpenWeatherMap service for weather information.

Do the following to enable weather information:

1. update WEATHER_API_KEY value in config/.env.local

Links

• Nest.js
• Postgres
• Prisma
• OpenWeatherMap