master	heroku
tests
coverage

'Explore Me SA GraphqQL' [server applicaion]

This project is centered around parsing various datasets, including UK government data on property sales, police reporting data, and post code data. The goal is to harness geographical information to establish connections between postcodes using latitude and longitude.

The primary objective is to develop a scalable GraphQL backend capable of swiftly delivering requested results. This endeavor seeks to illuminate intricate aspects of GraphQL use, addressing challenges like the N+1 problem and scaling scenarios where more than one database is required for both write and read nodes.

Key features of the project include a robust automated Quality Assurance (QA) system, incorporating anonymized data seeding for comprehensive QA testing. The project also explores the flexibility of JavaScript, pushing the boundaries of the language. Notably, it delves into the constraints of default V8 object fields, which are capped at around ~8.4 million, while highlighting the superior handling capacity of the Map data structure.

Additionally, the project incorporates a queue system to enhance the efficiency of data processing. In essence, project serves as a practical demonstration of diverse and advanced aspects of software development, reflecting a commitment to excellence and innovation.

• GraphQL live demo [currently unavailable]
• Web Application example of how data can be consumed
  • Web Application live demo [currently unavailable]

software requirements

if you're using make commands, docker and docker-compose are required, and local node.js with npm are optional

• node.js v18+
• npm v5+ or yarn
• optional makefile comes out of the box in unix enviroments
• optional docker v18.09+
• optional sqlite3 v3+ for 'integration' tests only

used technologies

• apollo server
• express.js
• sequlize
• dataloader
• graphql
• jest

used services

• circle ci
• codecov
• code climate
• snyk

where to get data-sets

• UK postcodes
• UK house sales data
• UK LSOA & Postcode data
• Police Records Data

how to install

• with make commands no steps additional are required, otherwise you need to execute $ npm i

how to run tests

• $ make test or $ npm test
  • optional 'jest' CLI params, examples:
    • to collect coverage, example: $ npm test -- --coverage, report will be located in ./coverage directory
    • to execute tests only in a specific file, for example: $ npm test src/graphql/user.test.js

how to set up a database

• database configuration is located in the file src/orm-config.js
• to get database schema up to date: $ npm run sql db:migrate, you can also create a database via ORM npm run sql db:create
• to seed the database with 'test' data: $ npm run sql db:seed:all

how to run in 'development' mode

• $ make or $ npm start

how to run in 'production' mode

• $ make serve, there is no npm equivalent
• if you only need to generate static assets
  • $ make build or $ npm run build - generated assets will be located in ./build directory

how to run containers with different variables using 'make'

• make PORT=18081

gitflow

• heroku -> current production, contains production specific changes, trigger production deploment on every push
• master -> most upto date production ready, all pull requests in to this branch got mandatory check 'ci/circleci: jest'
• feature branches -> get merged into the master branch when they are ready and mandatory checks passed
• CI executes tests in an isolated environment

used environment variables

Variable	Default Value	Type	Description
PORT	8081	number	The port on which the application will be available.
SSL_KEY		string	The absolute path to the SSL key (e.g., /home/ubuntu/private.key).
SSL_CERT		string	The absolute path to the SSL certificate (e.g., /home/ubuntu/certificate.crt).
***	***	***	If a replica's config is specified, non-replica connections are used only for writes.
DB_HOSTNAME	127.0.0.1	string	The host on which the database can be reached.
DB_USERNAME	root	string	The username for connecting to the database.
DB_PASSWORD	password	string	The password for the database user.
DB_PORT	3306	number	The port on which the database can be reached.
DB_NAME	explore	string	The name of the database schema.
DB_DIALECT	mysql	string	The database dialect, one of mysql / sqlite / postgres.
DB_REPLICA_HOSTNAME	127.0.0.1	string	The host of the database replica for read-only operations.
DB_REPLICA_USERNAME	root	string	The username for connecting to the database replica for read-only operations.
DB_REPLICA_PASSWORD	password	string	The password for the user connecting to the database replica for read-only operations.

data processors

NPM command	corresponding JS file
parse:postcodes	src/parse:postcodes
parse:postcodes:lsoa	src/parse:postcodes:lsoa
parse:incidents	src/parse:markers:and:incidents
parse:properties	src/parse:markers:and:properties
parse:areas	src/parse:areas
parse:timelines	src/parse:timelines

example: npm run parse:postcodes -- --file=/media/data/postcodes.csv

supported databases

database	version	adapter	main purpose
MySQL	8	mysql2	production
PostgreSQL	11	pg	production
SQLite	4	sqlite3	QA Automation & CI

• if you use MySQL 5.7+ you need to make sure it can work with mysql native password

• PostrgeSQL and SQLite are partially supported because some of the queries are not fully engine-agnostic, and some functions do not exist in SQLite for example