sort-eventstore/lib/eventStream.js

Node-eventstore is a node.js module for multiple databases. It can be very useful as eventstore if you work with (d)ddd, cqrs, eventsourcing, commands and events, etc.

var debug = require('debug')('eventstore:eventstream'),
  _ = require('lodash'),
  Event = require('./event');

/**
 * EventStream constructor
 * The eventstream is one of the main objects to interagate with the eventstore.
 * @param {Object} eventstore the eventstore that should be injected
 * @param {Object} query the query object
 * @param {Array} events the events (from store)
 * @constructor
 */
function EventStream (eventstore, query, events) {
  if (!eventstore) {
    var errESMsg = 'eventstore not injected!';
    debug(errESMsg);
    throw new Error(errESMsg);
  }

  if (typeof eventstore.commit !== 'function') {
    var errESfnMsg = 'eventstore.commit not injected!';
    debug(errESfnMsg);
    throw new Error(errESfnMsg);
  }

  if (!query) {
    var errQryMsg = 'query not injected!';
    debug(errQryMsg);
    throw new Error(errQryMsg);
  }

  if (!query.aggregateId) {
    var errAggIdMsg = 'query.aggregateId not injected!';
    debug(errAggIdMsg);
    throw new Error(errAggIdMsg);
  }

  if (events) {
    if (!_.isArray(events)) {
      var errEvtsArrMsg = 'events should be an array!';
      debug(errEvtsArrMsg);
      throw new Error(errEvtsArrMsg);
    }

    for (var i = 0, len = events.length; i < len; i++) {
      var evt = events[i];
      if (evt.streamRevision === undefined || evt.streamRevision === null) {
        var errEvtMsg = 'The events passed should all have a streamRevision!';
        debug(errEvtMsg);
        throw new Error(errEvtMsg);
      }
    }
  }

  this.eventstore = eventstore;
  this.streamId = query.aggregateId;
  this.aggregateId = query.aggregateId;
  this.aggregate = query.aggregate;
  this.context = query.context;
  this.events = events || [];
  this.uncommittedEvents = [];
  this.lastRevision = -1;

  this.events = _.sortBy(this.events, 'streamRevision');

  // to update lastRevision...
  this.currentRevision();
}

EventStream.prototype = {

  /**
   * This helper function calculates and returns the current stream revision.
   * @returns {Number} lastRevision
   */
  currentRevision: function() {
    for (var i = 0, len = this.events.length; i < len; i++) {
      if (this.events[i].streamRevision > this.lastRevision) {
        this.lastRevision = this.events[i].streamRevision;
      }
    }

    return this.lastRevision;
  },

  /**
   * adds an event to the uncommittedEvents array
   * @param {Object} event
   */
  addEvent: function(event) {
    new Event(this, event, this.eventstore.eventMappings);
  },

  /**
   * adds an array of events to the uncommittedEvents array
   * @param {Array} events
   */
  addEvents: function(events) {
    if (!_.isArray(events)) {
      var errEvtsArrMsg = 'events should be an array!';
      debug(errEvtsArrMsg);
      throw new Error(errEvtsArrMsg);
    }
    var self = this;
    _.each(events, function(evt) {
      self.addEvent(evt);
    });
  },

  /**
   * commits all uncommittedEvents
   * @param {Function} callback the function that will be called when this action has finished [optional]
   */
  commit: function(callback) {
    this.eventstore.commit(this, callback);
  }
};

module.exports = EventStream;