Reactive Java Spring Boot with Spring Data MongoDB

Overview

This project demonstrates a simplified cash balance application using reactive Java Spring Boot and Spring Data MongoDB. It includes:

• CRUD operations with ReactiveMongoRepository
• CRUD operations with ReactiveMongoTemplate
• Multi-document transaction handling

Supported Versions

• Java 17
• Spring Boot Starter Webflux 3.2.3
• Spring Boot Starter Reactive Data Mongodb 3.2.3
• Gradle 7.5.1

Application Workflow

1. Creation of a bank account with a unique accountNum, initializing with a $0 balance.
2. Storage of accounts and their balances in the "accounts" collection.
3. Debit operations to increase the account balance.
4. Credit operations to decrease the account balance.
5. Transfer operations to move funds from one account to another.
6. Transaction lifecycle:
   • Operations are initially recorded in the "transactions" collection with a "PENDING" status.
   • Account balances are updated.
   • Transaction status is updated to "SUCCESS".
7. Rollback transactions and mark as "FAILED" if:
   • Insufficient balance for debit operations.
   • Account number is invalid.

Setup Instructions

1. Ensure a MongoDB cluster is available.
2. Execute schema validation to enforce a non-negative balance:

mongosh "<MongoDB connection string>" --file setup.js

3. Create an application.properties file in the resources directory:

spring.data.mongodb.uri=<MongoDB connection string>
spring.data.mongodb.database=txn-demo

4. Compile the application:

./gradlew clean build

5. Run the application:

./gradlew bootRun

API Endpoints

Create Account

POST /account
Request Body:

{
  "accountNum": "<String>",
  "balance": "<Number>"
}

Example:

curl --location 'localhost:8080/account' \
--header 'Content-Type: application/json' \
--data '{
    "accountNum": "111111"
}'

Retrieve Account

GET /account/{accountNum}
Example:

curl --location 'localhost:8080/account/111111'

Debit Account

POST /account/{accountNum}/debit
Request Body:

{
  "amount": "<Number>"
}

Example:

curl --location 'localhost:8080/account/111111/debit' \
--header 'Content-Type: application/json' \
--data '{
    "amount": 1000
}'

Credit Account

POST /account/{accountNum}/credit
Request Body:

{
  "amount": "<Number>"
}

Example:

curl --location 'localhost:8080/account/111111/credit' \
--header 'Content-Type: application/json' \
--data '{
    "amount": 10000
}'

Transfer Funds

POST /account/{accountNum}/transfer
Request Body:

{
  "to": "<String>",
  "amount": "<Number>"
}

Example:

curl --location 'localhost:8080/account/123456/transfer' \
--header 'Content-Type: application/json' \
--data '{
    "to": "1111111",
    "amount": 500
}'

Testing with Postman

For functional testing, use the provided Postman collection to ensure API functionality:

1. Import the collection into Postman.
2. Set environment variables "host" and "port" in Postman.
3. Reset the database:

mongosh "<MongoDB connection string>" --file setup.js

4. Use the "Run collection" feature in Postman to execute all API calls sequentially and validate test results.

Testing with Rapid API Client

For local testing, the Rapid API Client can be utilized. Make sure the application is running locally and configure the client accordingly.