Chapter 3. Hooks, Actions, and Triggers

A common goal when working with Drupal is for something to happen when a certain event takes place. For example, a site administrator may want to receive an e-mail message when a message is posted. Or a user should be blocked if certain words appear in a comment. This chapter describes how to hook into Drupal's events to have your own code run when those events take place.

Understanding Events and Triggers

Drupal proceeds through a series of events as it goes about its business. These internal events are times when modules are allowed to interact with Drupal's processing. Table 3-1 shows some of Drupal's events.

Table 3.1. Examples of Drupal Events



Creation of a node


Deletion of a node


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