Ticker/Coin(btcusdt) Price Synchronizer

Description

Server application which periodically (every 10 seconds) fetches the BTCUSDT price (calling binance api) and stores it into database. It also exposes api with:

• current rate
• exchange rate history

Tech Stack

• Nest.js
• TypeScript
• GraphQL
• PostgreSQL
• TypeORM

Installation

Create .env file (inside the root directory) and copy variables from .env.example to .env.

Then run following commands:

# install dependencies
$ npm install

# start docker services (only database for now)
$ docker-compose up -d

# run the migrations
$ npm run migration:run

TypeORM migrations

Generating migration file

To auto-generate a migration file (sync database with all the fresh changes in the entities):

$ npm run migration:generate --name=NewMigrationName

After running the above command, make sure to import newly created migration to the root type-orm.config.ts file and add it to the existing array of migrations.

Running the migrations

When running the application for first time or once we have the migration added to the migrations array (above step):

$ npm run migration:run

It identifies that the migrations array contains a migration that wasn’t executed yet, then it runs the up method.

Reverting the migrations

To revert a migration:

$ npm run migration:revert

It executes the down method in the latest performed migration and removes the respective row from the migrations array. Therefore, if we need to revert more than one migration, we must use the command multiple times.

Creating the migrations manually

To create a migration manually:

$ npm run migration:create --name=NewMigrationName

In addition to automatically generating the migration for us, we can write its logic (SQL up and down methods queries) manually.

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

# test coverage
$ npm run test:cov