README

A MongoDB storage adapter for domainflow/event-sourcing-core — implements EventStorageInterface, SnapshotStorageInterface, SnapshotHistoryStorageInterface, and ProcessManagerStorageInterface against MongoDB. No domain logic of its own — no aggregate modeling, no business rules, just translation between Core's interfaces and MongoDB.

Requirements

PHP 8.4+
ext-mongodb 2.x
mongodb/mongodb ^2.0 composer package
A reachable MongoDB 7+ instance, running as a replica set (see below)

Installation

composer require domainflow/event-sourcing-mongodb

Production requirements

Run MongoDB as a replica set. Multi-document transactions have required one since MongoDB 4.0 and still do, and storeEvents() needs a transaction to append a whole call atomically — which is what EventStorageInterface promises: either every event in the call lands or none does, across every aggregate it touches.

On a standalone mongod there are no transactions, so the adapter refuses to write, throwing on the first storeEvents() call rather than quietly handing you something weaker than the interface says. A single-node replica set is enough to satisfy it, and is what docker-compose.yml runs.

If a standalone is genuinely what you have, opt out explicitly:

$storage = new MongoDbEventStorage($database, allowNonAtomicBatches: true);

That re-enables the fallback: a version pre-check, then an ordered insert, then a compensating delete of whatever landed before a failure. It is best-effort, not atomic — there is a real window between the check and the insert, and a process that dies between a failed insert and its compensation leaves the partial batch behind for good. The flag exists so that trade is a decision someone made, not one they were never told about.

Writes are durable by default and this is not configurable. Both collections are opened with w: majority, j: true. Under MongoDB's default (w: 1, j: false) an insert is acknowledged once one node holds it in memory, so an event can be reported as stored and then lost in a failover — leaving an aggregate that believes it emitted history the store never kept. That trade is not one an event store gets to make.

Development

docker compose up -d          # start a local MongoDB instance
composer install
composer quality              # lint + static analysis + full test suite (100% coverage required) + audit

License

MIT — see LICENSE.

domainflow / event-sourcing-mongodb

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