THESEEDFI ASSESSMENT

Description

This task demonstrate saving a numerical value (currency) with controlled precision to a PostgreSQL database using Node.js without data loss. This example will utilize native functionalities and avoid external frameworks like Express and ORM Libraries like TypeORM.

Research and Explanation to the Question Asked in The Interview

Answer: To save a floating-point value with 4 decimal places, such as 2053.0005, in a PostgreSQL database without losing precision

Recommended Approach: Using NUMERIC, DECIMAL or STRING Data Types

For financial applications or scenarios where precision is paramount, the preferred data types are NUMERIC and DECIMAL. These types offer:

• Exact Storage: They represent numbers precisely, avoiding rounding errors that can occur with floating-point data types.
• Scalability: They support a configurable number of decimal places, allowing you to tailor precision to your specific needs.

Example Usage:

CREATE TABLE transactions (
  id SERIAL PRIMARY KEY,
  amount NUMERIC(10, 4) NOT NULL -- 10 total digits (including potential sign), 4 decimal places
);

Alternative we can also handle it as a string, it's main by preference, this also prevent value from rounding up.

Features

• Create a Transaction: Endpoint to create a transaction.
• Get Transactions: Endpoint to get Transactions.

Prerequisites

• Node.js (20.x)
• PostgreSQL
• pg package npm i pg

Folder Structure

theseedfi_currency_transaction_tracker/
│
├── config/
│ └── db-migration.config.js.js # Migrations script for monitoring of database
| └── db-config.js # Used for creating new `PostgreSQl` connection
│
├── migrations/ # migration files
│
├── models/ #  models
│ └── transaction.model.js # Transactions model
│
├── controllers/ # Controllers for handling requests
│ └── transaction.controller.js
│
├── routes/ # Route definitions
│ └── transaction.route.js.js
│
├── .env # Environment variables
├── index.js # Entry point of the application
├── package.json # NPM package file
└── README.md # Project README

Getting Started

1. Clone the repository:

$ git clone repo url
$ cd theseedfi_currency_transaction_tracker

2. Create a .envfile and put in the right credentials:

cp .env.example .env
source .env

PS: ensure you fill your .env file before starting the server

3. Start the Server

$ npm install 
$ npm run dev

APIs Documentation

Base URL

The base URL for the API is: http://localhost:3000

Endpoints

Create Transaction

Endpoint: /transactions

Method: POST

Description: This endpoint allows you to create a new transaction.

Request Body:

Field	Type	Description
amount	number	The amount for the transaction
description	string	A description for the transaction

Response:

Success (201 Created):

{
  "message" : "Transaction created",
  "data": {
    "id": 1,
    "amount": 100.0000,
    "description": "Sample transaction",
  }
}

Example Usage

$ curl -X POST http://localhost:3000/transactions \
     -H "Content-Type: application/json" \
     -d '{
           "amount": 100.00,
           "description": "Sample transaction"
        }'

Get all Transactions

Endpoint: /transactions

Method: GET

Description: This endpoint get all transactions.

Request Body:

Response:

Success (200 Success):

{
  "message" : "Success",
  "data": [
    {
        "id": 1,
        "amount": 100.0000,
        "description": "Sample transaction",
    },
    {
        "id": 2,
        "amount": 200.0000,
        "description": "Another transaction",
    }
  ]
}

Example Usage

$ curl -X GET http://localhost:3000/transactions