3 unstable releases
0.4.0 | Sep 8, 2024 |
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0.3.1 | Feb 26, 2024 |
0.2.1 |
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0.2.0 |
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0.1.0 |
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#529 in Rust patterns
Used in eventastic_postgres
26KB
388 lines
Eventastic
This is an opinionated fork of Eventually-rs.
Eventastic enforces the use of transactions, handles idempotency and removes command handling abstractions.
Examples
See full examples in examples/bank
#[tokio::main]
async fn main() -> Result<(), anyhow::Error> {
// Setup postgres repo
let repository = get_repository().await;
// Run our side effects handler in a background task
tokio::spawn(async {
let repository = get_repository().await;
let _ = repository
.start_outbox(SideEffectContext {}, std::time::Duration::from_secs(5))
.await;
});
// Start transaction
let mut transaction = repository.begin_transaction().await?;
let account_id = Uuid::new_v4();
let event_id = Uuid::new_v4();
let add_event_id = Uuid::new_v4();
// Open a bank account
let event = AccountEvent::Open {
event_id,
account_id,
starting_balance: 21,
email: "user@example.com".into(),
};
let mut account = Account::record_new(event)?;
// Add funds to newly created account
let add_event = AccountEvent::Add {
event_id: add_event_id,
amount: 324,
};
// Record add fund events.
// Record takes in the transaction, as it does idempotency checks with the db.
account
.record_that(&mut transaction, add_event.clone())
.await?;
// Save uncommitted events and side effects in the db.
transaction.store(&mut account).await?;
// Commit the transaction
transaction.commit().await?;
// Get the aggregate from the db
let mut transaction = repository.begin_transaction().await?;
let mut account: Context<Account> = transaction.get(&account_id).await?;
// Check our balance is correct
assert_eq!(account.state().balance, 345);
// Trying to apply the same event id but with different content gives us an IdempotencyError
let changed_add_event = AccountEvent::Add {
event_id: add_event_id,
amount: 123,
};
let err = account
.record_that(&mut transaction, changed_add_event)
.await
.expect_err("failed to get error");
assert!(matches!(err, RecordError::IdempotencyError(_, _)));
// Applying the already applied event, will be ignored and return Ok
account.record_that(&mut transaction, add_event).await?;
transaction.commit().await?;
let mut transaction = repository.begin_transaction().await?;
let account: Context<Account> = transaction.get(&account_id).await?;
// Balance hasn't changed since the event wasn't actually applied
assert_eq!(account.state().balance, 345);
println!("Got account {account:?}");
tokio::time::sleep(std::time::Duration::from_secs(30)).await;
Ok(())
}
Dependencies
~1–1.8MB
~37K SLoC