Crate sqlx_ledger

sqlx-ledger

This crate builds on the sqlx crate to provide a set of primitives for implementing an SQL-compatible double-entry accounting system. This system is engineered specifically for dealing with money and building financial products.

Quick Start

Add and execute the migrations from the migrations directory before usage.

cp ./migrations/* <path/to/your/projects/migrations>
# in your project
cargo sqlx migrate

Here is how to initialize a ledger create a primitive template and post a transaction. This is a toy example that brings all pieces together end-to-end. Not recommended for real use.

use uuid::uuid;
use rust_decimal::Decimal;
use sqlx_ledger::{*, journal::*, account::*, tx_template::*};

async fn init_ledger(journal_id: JournalId) -> SqlxLedger {
    let pg_con =
        std::env::var("PG_CON").unwrap_or(format!("postgres://user:password@localhost:5432/pg"));
    let pool = sqlx::PgPool::connect(&pg_con).await.unwrap();
    let ledger = SqlxLedger::new(&pool);

    // Initialize the journal - all entities are constructed via builders
    let new_journal = NewJournal::builder()
        .id(journal_id)
        .description("General ledger".to_string())
        .name("Ledger")
        .build()
        .expect("Couldn't build NewJournal");

    let _ = ledger.journals().create(new_journal).await;

    // Initialize an income omnibus account
    let main_account_id = uuid!("00000000-0000-0000-0000-000000000001");
    let new_account = NewAccount::builder()
        .id(main_account_id)
        .name("Income")
        .code("Income")
        .build()
        .unwrap();

    let _ = ledger.accounts().create(new_account).await;

    // Create the trivial 'income' template
    //
    // Here are the 'parameters' that the template will require as inputs.
    let params = vec![
        ParamDefinition::builder()
            .name("sender_account_id")
            .r#type(ParamDataType::UUID)
            .build()
            .unwrap(),
        ParamDefinition::builder()
            .name("units")
            .r#type(ParamDataType::DECIMAL)
            .build()
            .unwrap()
    ];

    // The templates for the Entries that will be created as part of the transaction.
    let entries = vec![
        EntryInput::builder()
            .entry_type("'INCOME_DR'")
            // Reference the input parameters via CEL syntax
            .account_id("params.sender_account_id")
            .layer("SETTLED")
            .direction("DEBIT")
            .units("params.units")
            .currency("'BTC'")
            .build()
            .unwrap(),
        EntryInput::builder()
            .entry_type("'INCOME_CR'")
            .account_id(format!("uuid('{main_account_id}')"))
            .layer("SETTLED")
            .direction("CREDIT")
            .units("params.units")
            .currency("'BTC'")
            .build()
            .unwrap(),
    ];
    let tx_code = "GENERAL_INCOME";
    let new_template = NewTxTemplate::builder()
        .id(uuid::Uuid::new_v4())
        .code(tx_code)
        .params(params)
        .tx_input(
            // Template for the Transaction metadata.
            TxInput::builder()
                .effective("date()")
                .journal_id(format!("uuid('{journal_id}')"))
                .build()
                .unwrap(),
        )
        .entries(entries)
        .build()
        .unwrap();

    let _ = ledger.tx_templates().create(new_template).await;

    ledger
}

tokio_test::block_on(async {
    let journal_id = JournalId::from(uuid!("00000000-0000-0000-0000-000000000001"));
    let ledger = init_ledger(journal_id).await;

    // The account that is sending to the general income account
    let sender_account_id = AccountId::new();
    let sender_account = NewAccount::builder()
        .id(sender_account_id)
        .name(format!("Sender-{sender_account_id}"))
        .code(format!("Sender-{sender_account_id}"))
        .build()
        .unwrap();
    ledger.accounts().create(sender_account).await.unwrap();

    // Prepare the input parameters that the template requires
    let mut params = TxParams::new();
    params.insert("sender_account_id", sender_account_id);
    params.insert("units", Decimal::ONE);

    // Create the transaction via the template
    ledger
        .post_transaction(TransactionId::new(), "GENERAL_INCOME", Some(params))
        .await
        .unwrap();

    // Check the resulting balance
    let account_balance = ledger
        .balances()
        .find(journal_id, sender_account_id, "BTC".parse().unwrap())
        .await
        .unwrap();

    assert_eq!(account_balance.unwrap().settled(), Decimal::NEGATIVE_ONE);
});

Modules

account

Account holds a balance in a Journal

balance

AccountBalance and BalanceDetails are segregated per journal and currency.

entry

Entries represent discrete changes in the ledger. Grouped as Transactions

event

Use ledger.events() to subscribe to events triggered by changes to the ledger.

journal

Journals are ledgers holding transactions and entries that must always be balanced.

transaction

A Transaction holds metadata and is referenced by its Entries.

tx_template

All Transactions are created via templates to ensure consistency.

Macros

entity_id

Structs

AccountId

CorrelationId

EntryId

JournalId

SqlxLedger

TransactionId

TxTemplateId

Enums

Currency

DebitOrCredit

Layer

SqlxLedgerError

Status