@coriolis/coriolis/src/eventBuilder.js

Event sourced effect management

import { identity } from './lib/function/identity'

const stringifyTo = (type, obj) => {
  obj.toString = () => type

  return obj
}

export const createEventBuilder = (
  type,
  payloadBuilder = identity,
  metaBuilder,
  empty = {},
) =>
  stringifyTo(type, (args = empty) => {
    const event = { type }
    let payload
    let meta

    try {
      payload = payloadBuilder(args)
    } catch (error) {
      payload = error
      event.error = true
    }

    if (metaBuilder) {
      try {
        meta = metaBuilder(args)
      } catch (error) {
        payload = error
        event.error = true
      }
    }

    if (payload !== empty) {
      event.payload = payload
    }

    if (meta) {
      event.meta = meta
    }

    if (payload instanceof Error) {
      event.error = true
    }

    return event
  })