event-store-adapter-rs

This library is designed to turn DynamoDB into an Event Store for Event Sourcing.

日本語

Usage

You can easily implement an Event Sourcing-enabled repository using EventStore.

pub struct UserAccountRepository {
  event_store: EventStore<UserAccount, UserAccountEvent>,
}

impl UserAccountRepository {
  pub fn new(event_store: EventStore<UserAccount, UserAccountEvent>) -> Self {
    Self { event_store }
  }

  pub async fn store(
    &mut self,
    event: &UserAccountEvent,
    version: usize,
    snapshot_opt: Option<&UserAccount>,
  ) -> Result<()> {
    match (event.is_created(), snapshot_opt) {
      (false, None) => {
        self.event_store.persist_event(event, version).await?;
      }
      (true, None) => {
        panic!("Invalid state")
      }
      (_, Some(snapshot)) => {
        self.event_store.persist_event_and_snapshot(event, snapshot).await?;
      }
    }
    Ok(())
  }

  pub async fn find_by_id(&self, id: &UserAccountId) -> Result<UserAccount> {
    let snapshot = self.event_store.get_latest_snapshot_by_id(id).await?;
    match snapshot {
      Some((snapshot, version)) => {
        let events = self.event_store
          .get_events_by_id_since_seq_nr(id, snapshot.seq_nr)
          .await?;
        let result = UserAccount::replay(events, snapshot, version);
        Ok(Some(result))
      }
      None => Ok(None),
    }
  }
    
}

The following is an example of the repository usage

let event_store = EventStore::new(
  aws_dynamodb_client.clone(),
  journal_table_name.to_string(),
  journal_aid_index_name.to_string(),
  snapshot_table_name.to_string(),
  snapshot_aid_index_name.to_string(),
  64,
);
 
let mut repository = UserAccountRepository::new(event_store);
 
// Replay the aggregate from the event store
let mut user_account = repository.find_by_id(user_account_id).await.unwrap();

// Execute a command on the aggregate
let user_account_event = user_account.rename(name).unwrap();
 
// Store the new event without a snapshot
repository
  .store(&user_account_event, user_account.version(), None)
  .await
// Store the new event with a snapshot
//  repository
//  .store(&user_account_event, user_account.version(), Some(&user_account))
//  .await

Table Specifications

See docs/DATABASE_SCHEMA.md.