Professional Joomla!

Chapter 5. Developing Simple Extensions: Modules

While the huge library of existing Joomla extensions can fill most needs, many sites will eventually need some custom programming. This often means using a custom extension to display information in a specific fashion. Modules are the simplest form of extensions in Joomla, and they are generally either display-only or accept only minimal user input.

Modules are used in Joomla for most of the basic front page display, including the menus, the banners, the search inputs, and polls. Often, a module will provide the presentation aspects of an associated component. For example, the search module displays the text fields for input that is passed to the search component that actually runs the query. Since modules are primarily display-only, they are usually very easy to implement and deploy.

This chapter shows you how to create three modules:

• The first module displays a simple Hello World greeting and provides a good foundation atop which you can build nearly any type of module.

• The second module uses a custom table in the database to display holiday greetings. If the current day matches one of the holiday dates stored in the database, the linked greeting appears inside the module.

• The third module uses the infrastructure provided by the Contacts component to retrieve and display a list of custom contact information.

As you progress through the construction of these components, you will learn how to use the Joomla Administrator interface to configure ...