Service - User Account Balance

Overview

Manages a users balance owed to the project.

Repository

https://bitbucket.org/izara-core-user-accounts/izara-core-user-accounts-user-account-balance

DynamoDB tables

Standard Config Table Per Service

Configuration tags

{
	configKey: "..."
	configTag: "..."
	configValue: xxx // eg: "..."
}

UserBalance

{
	userId: xxx
	balance: xxx
	currencyId: ###
}

• partition key: userId
• sort key: (none)
• record is created when user is first made, but if it does not for some reason we could perhaps make the record with a default currency (eg USD)

Transaction

• Want to be able to filter by time

{
	userId: xxx
	timeTransactionId: xxx
	amount: xxx
	transactionTag: xxx
	currencyId: ###
	originalCurrencyId: ###
	originalAmount: xxx
	conversionRate: xxx
}

• partition key: userId
• sort key: timeTransactionId
• timeTransactionId: {timestamp}_{random uuid for transactionId} add uuid to ensure each sortKey is unique
• transactionTag: standardized tag set be external service to identify the type of transaction
• currencyId: record the converted to currency (will match UserBalance currency unless we allow to change currency in future)
• originalCurrencyId: of the transaction amount from external service
• originalAmount: from external service before conversion to user's currency
• conversionRate: record the rate used to perform conversion

Currency

Each user sets the currency they want their account balance to be recorded in, when a transaction is received it notes which currency the amount was calculated in and this service converts it to the user's currency using our systems mid-market exchange rates.

Running balance

When a transaction is received, converted, and saved we update the user's balance. Be careful of race conditions and perhaps code a flow that recalculates the balance from all transactions, similar to account limits.

When user goes negative

Perhaps trigger adding roles to the user that restrict their limits/access to actions.

Working documents

User Account Balance