Kotlin Ktor Exposed Starter

This is a starter project for a RESTful API application, implemented in Kotlin using Ktor, Exposed, and an H2 in-memory database.

Author: Ebubekir Yiğit

Objective: The application serves as a demonstration of a simple financial transfer system, allowing customers to transfer funds from their wallet to a restaurant's account upon making a purchase.

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Features

• The application can transfer funds from a customer's wallet to a restaurant's account.
• The transfer operation validates that the customer has sufficient funds in their wallet and that the transfer amount does not exceed their daily limit.
• The application can display the balances in both customer and restaurant accounts.

Prerequisites

• You need to have Kotlin and Java installed on your local machine. This guide assumes you have the Java Development Kit (JDK) version 11 or higher installed.

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Getting Started

Running the Application

To start the application, run the following command in the root directory of the project:

./gradlew run

Running the Tests

To run the tests, use the following command:

./gradlew test

Endpoints

• POST /transactions: Takes the TransferRequest object and transfers the amount from the customer's account to the restaurant's account.

Transaction Request:

{
    "customerId": 2,
    "restaurantId": 1,
    "amount": 3.5
}

Transaction Response:

{
    "success": true,
    "data": {
        "transactionId": 1,
        "customerId": 2,
        "restaurantId": 1,
        "amount": 3.5
    }
}

• GET /accounts/customer/{id}: Returns the balance of the customer's account with the given id.
• GET /accounts/restaurant/{id}: Returns the balance of the restaurant's account with the given id.

Account Balance Response:

{
    "success": true,
    "data": {
        "accountId": 2,
        "balance": 26.5
    }
}

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Project Structure

├── main
│   ├── kotlin
│   │   ├── database       # Database initialization, migration etc.
│   │   ├── models         # Request, Response and DB Models
│   │   ├── repositories   # Database actions, storage layer
│   │   ├── routes         # Endpoint definitions
│   │   └── services       # Business logic
└── test
    └── kotlin
        ├── api            # API tests
        └── service        # Service tests

Acknowledgments

This project uses the following libraries:

• Ktor
• Exposed
• H2 Database Engine
• HikariCP
• Flyway
• JUnit