eventastic

An event store on top of RethinkDB.

Installation

Important: Please not that this is alpha software and currently a work in progress. API may change in the next releases. Nevertheless, I encourage you to give it a test drive and provide feedback how you like it :)

npm i --save eventastic

or if you are using yarn:

yarn add eventastic

Usage

import createEventStore, { createEvent } from "eventastic";

const app = async () => {
    const es = await createEventStore({
        host: 'localhost',
        port: 32793
    });

    const user: IUser = {
        username: "akoenig",
        firstname: "André",
        lastname: "König",
        email: "[e-mail]",
        password: "e3b0c4....",
        salt: "852b85...."
    };

    const UserRegisteredEvent = createEvent<IUser>('UserRegisteredEvent');

    await es.commit(UserRegisteredEvent(user));
};

Changefeed

eventastic comes with a changefeed implementation which allows further processing of the event after it has been persisted (e. g. publish to message broker, etc.).

import createEventStore, { createEvent } from "eventastic";

const app = async() => {
    const es = await createEventStore({
        host: 'localhost',
        port: 32793
    });

    await es.changes((err: Error, event: IEvent<any>) => {
        if (err) {
            // Handle error ...
        }

        console.log(`A new event has been persisted: ${JSON.stringify(event)}.`);

        // Publish to message broker etc. ...
    });
};

Projections

import createEventStore from "eventastic";
import createProjection, { when } from "eventastic/projection";

const app = async() => {
    const es = await createEventStore({
        host: 'localhost',
        port: 32793
    });

    const UserCount = createProjection(
        when('UserRegisteredEvent', (count: number, event: IEvent<IUser>) => count++),
        when('UserUnregisteredEvent', (count: number, event: IEvent<IUser>) => count--)
    );

    const registeredUserCount = await es.project(UserCount);

    console.log(`We have ${registeredUserCount} user(s). Yay!`);
};

Replay all events

import createEventStore from "eventastic";

const app = async() => {
    const es = await createEventStore({
        host: 'localhost',
        port: 32793
    });

    await es.replay(event => {
        // Do something with the event
    });

    console.log(`We have ${registeredUserCount} user(s). Yay!`);
};

License

MIT © André König