@eventstore/db-client

@eventstore/db-client

This is the package for the NodeJS client for EventStoreDB 20+ and uses gRPC as the communication protocol.

Installation

# Yarn

$ yarn add @eventstore/db-client


# NPM

$ npm install --save @eventstore/db-client

EventStoreDB Server Compatibility

This client is compatible with version 20.6.1 upwards.

Server setup instructions can be found under the installation section of the Event Store Docs. Follow the Docker setup for the simplest configuration.

Example

The following snippet showcases a simple example where we form a connection, then append and read events from the server.

Javascript example:

const {
  EventStoreDBClient,
  jsonEvent,
  FORWARDS,
  START,
} = require('@eventstore/db-client');

const client = new EventStoreDBClient({
  endpoint: "localhost:2113",
});

async function simpleTest() {
  const streamName = "es_supported_clients";

  const event = jsonEvent({
    type: "grpc-client",
    data: {
      languages: ["typescript", "javascript"],
      runtime: "NodeJS",
    },
  });

  const appendResult = await client.appendToStream(streamName, [event]);

    // read the event
    const events = client.readStream(streamName, {
      fromRevision: START,
      direction: FORWARDS,
      maxCount: 10,
    });

    for await (const { event } of events) {
      console.log('Appended event: ', event);
    }
  } catch (error) {
    console.error('An error occured: ', error);
  } finally {
    await client.dispose();
  }
})();

Typescript example:

import {
  EventStoreDBClient,
  jsonEvent,
  FORWARDS,
  START,
  JSONEventType,
} from '@eventstore/db-client';

const client = new EventStoreDBClient({
  endpoint: 'localhost:2113',
});

interface Reservation {
  reservationId: string;
  movieId: string;
  userId: string;
  seatId: string;
}

type SeatReservedEvent = JSONEventType<
  'seat-reserved',
  {
    reservationId: string;
    movieId: string;
    userId: string;
    seatId: string;
  }
>;

type SeatChangedEvent = JSONEventType<
  'seat-changed',
  {
    reservationId: string;
    newSeatId: string;
  }
>;

type ReservationEvents = SeatReservedEvent | SeatChangedEvent;

async function simpleTest(): Promise<void> {
  const streamName = 'booking-abc123';

  const event = jsonEvent<SeatReservedEvent>({
    type: 'seat-reserved',
    data: {
      reservationId: 'abc123',
      movieId: 'tt0368226',
      userId: 'nm0802995',
      seatId: '4b',
    },
  });

  const appendResult = await client.appendToStream<ReservationEvents>(
    streamName,
    event
  );

  // By reading the events in the stream, we can construct the current state of the booking

  interface Reservation {
    reservationId: string;
    movieId: string;
    userId: string;
    seatId: string;
  }

  const events = client.readStream<ReservationEvents>(streamName, {
    fromRevision: START,
    direction: FORWARDS,
    maxCount: 10,
  });

  const reservation: Partial<Reservation> = {};

  for await (const { event } of events) {
    switch (event.type) {
      case 'seat-reserved': {
        reservation.reservationId = event.data.reservationId;
        reservation.movieId = event.data.movieId;
        reservation.seatId = event.data.seatId;
        reservation.userId = event.data.userId;
        break;
      }
      case 'seat-changed': {
        reservation.seatId = event.data.newSeatId;
        break;
      }
      default: {
        const _exhaustiveCheck: never = event;
        break;
      }
    }
  }
}

// Do something with our reservation
console.log(reservation);

Support

Information on support can be found on our website: Event Store Support

Communities

• Discuss
• Discord (Event Store)
• Discord (ddd-cqrs-es)

Contributing

Refer to our Contribution Guidelines