Event handler

Overview

Event handler — is a simple function that receives event as an argument and performs required logic. All event handlers should be stored in the /handlers folder within resource. Handler name should include event name e.x. user.created.handler.ts. That helps find all places were event is used. Direct database updates of the current resource entity are allowed within handler.

Examples

import { eventBus, InMemoryEvent } from '@paralect/node-mongo';

import ioEmitter from 'io-emitter';

import { DATABASE_DOCUMENTS } from 'app-constants';
import { Document } from 'types';

const { DOCUMENTS } = DATABASE_DOCUMENTS;

eventBus.on(`${DOCUMENTS}.created`, (data: InMemoryEvent<Document>) => {
    try {
        const document = data.doc;

        ioEmitter.publishToUser(document.userId, 'document:created', document);
    } catch (error) {
      logger.error(`${DOCUMENTS}.created handler error: ${error}`);
    }
})

import { eventBus, InMemoryEvent } from '@paralect/node-mongo';

import { DATABASE_DOCUMENTS } from 'app-constants';
import { User } from 'types';

const { USERS } = DATABASE_DOCUMENTS;

eventBus.onUpdated(USERS, ['firstName', 'lastName'], (data: InMemoryEvent<User>) => {
    const user = data.doc;
    const fullName = user.lastName ? `${user.firstName} ${user.lastName}` : user.firstName;

    console.log(`User fullName was updated: ${fullName}`)
})