Prooph Event Store: Query event stream

Merger.php

<?php

final class Merger
{
    // ...
    private function getInitialEventFromStream(EmploymentContractId $contractId): EmploymentContractSigned
    {
        $query = $this->projectionManager->createQuery();
        $query
            ->init(function (): array {
                return [];
            })
            ->fromStream('employment_contract_stream')
            ->when([
                EmploymentContractSigned::class => function (
                    array $state, EmploymentContractSigned $event
                ) use ($contractId): array {
                    if ($event->contractId()->sameValueAs($contractId)) {
                        $state[] = $event;

                        $this->stop();
                    }

                    return $state;
                }
            ])
            ->run();

        return $query->getState()[0];
    }
}

Came from:

• https://twitter.com/webdevilopers/status/1285137179849752576

/cc @prolic

Docs:

• http://docs.getprooph.org/event-store/projections.html

A alternative with a Metadatamatcher

<?php

final class Merger
{
    // ...
    private function getInitialEventFromStream(EmploymentContractId $contractId): EmploymentContractSigned
    {
        $metadataMatcher = (new MetadataMatcher())
            ->withMetadataMatch('_aggregate_id', Operator::EQUALS(), $contractId->toString());

        $query = $this->projectionManager->createQuery();
        $query
            ->init(function (): array {
                return [];
            })
            ->fromStream('employment_contract_stream', $metadataMatcher)
            ->when([
                EmploymentContractSigned::class => function (
                    array $state, EmploymentContractSigned $event
                ): array {
                    $state[] = $event;

                    return $state;
                }
            ])
            ->run();

        return $query->getState()[0];
    }
}

I think the alternative using a metadata matcher would result in better performance. Other than hand-written manual sql queries, this should be the best approach.

Worked like a charm @fjogeleit @prolic! Thank you for this.

Update fromStream for Projection, Query and ReadModelProjection:

• prooph/event-store@68a823c#diff-e3e2a9bfd88566b05001b02a3f51d286