Minibank API

This is a small bank REST API that I made with Express, TypeScript, TypeORM and PostgreSQL. I built it to learn TypeORM relations (one-to-many and many-to-many) and how to document an API with Swagger.

Features

• Create and delete bank clients
• Create bankers and connect a banker to a client (many-to-many)
• Deposit and withdraw money for a client (one-to-many transactions)
• A withdraw can't make the balance go below 0
• Amounts are checked: they must be positive numbers with max 2 decimal places
• Every deposit/withdraw runs in a database transaction and locks the client row, so two requests at the same time can't break the balance
• Swagger docs for all routes
• A Postman collection is in Minibank-api.postman_collection.json

Built with

• Node.js and TypeScript
• Express
• TypeORM
• PostgreSQL
• Swagger (swagger-jsdoc and swagger-ui-express)
• pino for logging

How to run

You need Node.js (18 or newer) and Docker (or your own PostgreSQL).

1. Clone the repo and install packages:

   git clone https://github.com/IkboljonMe/minibank-api.git
   cd minibank-api
   npm install

2. Start PostgreSQL with Docker:

   docker run -d --name minibank-pg -e POSTGRES_PASSWORD=postgres -p 5432:5432 postgres:15

3. Create the .env file:

   cp .env.example .env

   The values in .env.example already work with the Docker command above.

4. Start the server:

   npm start

   The tables are created automatically on the first start (TypeORM synchronize). The server runs on http://localhost:1337.

To check the TypeScript types you can run npm run typecheck.

Environment variables

Name	Example	What it is
SERVER_PORT	1337	Port for the Express server
PG_HOST	localhost	PostgreSQL host
PG_PORT	5432	PostgreSQL port
PG_USERNAME	postgres	PostgreSQL user
PG_PASSWORD	postgres	PostgreSQL password
PG_DATABASE	postgres	Database name
NODE_ENV	(empty)	If it is production, TypeORM will not change the tables automatically

API routes

Method	Route	What it does
POST	/api/client	Create a client (firstName, lastName, email, cardNumber, optional balance)
DELETE	/api/client/:clientId	Delete a client and their transactions
POST	/api/client/:clientId/transaction	Deposit or withdraw (type: deposit or withdraw, amount)
POST	/api/banker	Create a banker (firstName, lastName, email, cardNumber, employeeNumber)
PUT	/api/banker/:bankerId/client/:clientId	Connect a banker to a client

Example deposit:

curl -X POST http://localhost:1337/api/client/1/transaction \
  -H "Content-Type: application/json" \
  -d '{"type": "deposit", "amount": 50}'

Errors come back as JSON like {"error": "Insufficient funds"} with status 400, 404 or 409.

Swagger docs

When the server is running, open http://localhost:1337/docs. The raw OpenAPI JSON is at http://localhost:1337/docs.json.

Project structure

src/
  app.ts            starts the server
  controllers/      route handlers (client, banker, transaction)
  entities/         TypeORM entities (Client, Banker, Transaction)
  middlewares/      request body check
  routes/           Express routes with Swagger comments
  utils/            database connection, logger, swagger setup

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Made by IkboljonMe