Elgg 1.8 Social Networking

Lesson 4: Doing something when X happens

This lesson explains how to use Elgg's event system.

Problem

Whenever someone joins a group, you want to send an e-mail welcoming them. Whenever a blog entry is posted, you want to be notified so that you can review its content. Whenever someone logs in, you want to increase a counter so that you can proudly post on your front page how many times people have used your site: "3 billion served". In all of these cases, an event occurs and you want something to happen.

Solution

Elgg has an event system that calls a function when something occurs. When a user logs in, a login event is triggered within Elgg. Events are triggered for updating profile fields, joining a group, forming a friendship, uploading a file, ...