Mangrove Offchain Server

Creates offchain index of mangrove.exchange and provides GraphQL endpoint.

It uses Prisma ORM framework to work with Postgresql. Apollo is used as GraphQL server. GraphQL schema and resolvers are generated with TypeGraphQL and its Prisma Integration

Development

Requirements

• node.js v16
• yarn
• postgresql instance (can be started with docker-compose)

Start postgresql

yarn docker:env

Prisma Schema

Prisma schema is located at prisma/schema.prisma.

Change Schema

Manually adjust schema file and run yarn prisma:migrate {migrationname} create SQL migration and generate client code.

Deploy Schema

Run yarn prisma:deploy to apply all migrations to selected database (connection string is taken from DATABASE_URL env var).

(!) Check out .env.development and .env.test file

Useful commands

• yarn start:consumer to start event stream consumer
• yarn start:server to start graphql server
• yarn test to run all tests
• yarn test:integration to run all integration tests
• yarn test:unit to run all unit tests
• yarn start:test:server to run Apollo on test database. (useful when debugging tests)
• yarn debug:integration to run all integrations tests in debug mode
• yarn debug:unit to run all unit tests in debug mode
• yarn lint to run linter

Versioning of entities

Events should not overwrite/delete data, as the data might have to be restored if the event is undone. Instead of overwrites/deletes of entities, the following versioning pattern is applied:

• prisma.Entity is the base entity with immutable data (such as id, mangrove id, ...)

  • currentVersionId is the id of the current version of the entity
  • deleted = true means the entity has been deleted

• prisma.EntityVersion contains the data that can change when the entity is updated

  • versionNumber is an incremental version number, starting at zero
  • prevVersionId is the id of an older version that this version replaces, if any

On undo of an event that created a version, that version is deleted and the previous version set as the current. If there was no previous version, the entity itself is deleted (not just marked as deleted, as the undo can never be undone).