Building Custom Components in Joomla 1.5

Introduction Toby Patterson Executive Director of GMITC http://www.gmitc.biz

Toby Patterson

Executive Director of GMITC

http://www.gmitc.biz

Purpose Explain how to implement your business logic using a custom Joomla! component; Introduce to the Joomla MVC and other system resources; Demonstrate some code. The purpose of this presentation is to:

Explain how to implement your business logic using a custom Joomla! component;

Introduce to the Joomla MVC and other system resources;

Demonstrate some code.

The purpose of this presentation is to:

Do you need an extension? How many people ... ? Already have Joomla Websites? Use Joomla 3PD extensions? Want an extension that doesn't ( yet ) exist? Are developers, have developers, or will hire developers to create an extension?

How many people ... ?

Already have Joomla Websites?

Use Joomla 3PD extensions?

Want an extension that doesn't ( yet ) exist?

Are developers, have developers, or will hire developers to create an extension?

What is an extension? A Joomla! Extension ... Implements your business logic, Does not alter the Joomla core, so that you can easily perform upgrades, Should ( but does not have to ) use the Joomla Framework.

A Joomla! Extension ...

Implements your business logic,

Does not alter the Joomla core, so that you can easily perform upgrades,

Should ( but does not have to ) use the Joomla Framework.

Why Write an Extension You may wish to write an extension if you have specific business logic that an existing extension does not perform or does not perform the task as you need.

You may wish to write an extension if you have specific business logic that an existing extension does not perform or does not perform the task as you need.

Examples of Extension Tasks Displaying customer information. Placing an order Entering information about a person Checking the status of an application Changing a client's request Sending a notification many more ... ( this is where I ask for suggestions )

Displaying customer information.

Placing an order

Entering information about a person

Checking the status of an application

Changing a client's request

Sending a notification

many more ... ( this is where I ask for suggestions )

Extensions in the Joomla Framework Components - Interactive screens representing business logic. Modules - Displayed in specific areas of a template. Plugins - Extend the Joomla Framework. It is easy to implement business logic using custom extensions.

Components - Interactive screens representing business logic.

Modules - Displayed in specific areas of a template.

Plugins - Extend the Joomla Framework.

It is easy to implement business logic using custom extensions.

Joomla 1.5's MVC Model-View-Controller Software Design Pattern Business, presentation, and control logic are separate You can change one part without affecting another ( yay ! ) Joomla 1.5 is the first version of Joomla that uses a MVC design pattern ( double yay ! )

Model-View-Controller

Software Design Pattern

Business, presentation, and control logic are separate

You can change one part without affecting another ( yay ! )

Joomla 1.5 is the first version of Joomla that uses a MVC design pattern ( double yay ! )

What is an MVC Model - The model is the part of the component that encapsulates the application’s data and business logic – it does the work. View - The view is the part of the component that is used to render the data from the model using a layout file – it creates the interface. Controller - The controller will determine what request has been made by the user and respond appropriately using the model and view – it controls who does what and when.

Model - The model is the part of the component that encapsulates the application’s data and business logic – it does the work.

View - The view is the part of the component that is used to render the data from the model using a layout file – it creates the interface.

Controller - The controller will determine what request has been made by the user and respond appropriately using the model and view – it controls who does what and when.

Just Remember Just remember: Components implement custom business logic rules. You may need to write your own component to express business logic specific to you. Joomla 1.5 provides an MVC to help you write a component.

Just remember:

Components implement custom business logic rules.

You may need to write your own component to express business logic specific to you.

Joomla 1.5 provides an MVC to help you write a component.

Implementing the Simplest Component 1. Create the directory JOOMLA/components/com_hello/ 2. Create the file JOOMLA/components/com_hello/hello.php 3. Add the following code to the file <?php echo 'Hello World' ?> 4. Execute the following SQL query insert into jos_components values ( NULL, 'Hello', '', 0, 0, '', '', 'com_hello', 0, '', 0, '', 1 ); 5. Access the page using the following URL index.php?option=com_hello

New to the MVC? The Joomla Dev Website offers a sample hello component that you can experiment with.

The Joomla Dev Website offers a sample hello component that you can experiment with.

File System Layout Files that you will see in the hello tutorial once installed. http://dev.joomla.org/component/option,com_jd-wiki/Itemid,/id,tutorials:components/

Files that you will see in the hello tutorial once installed.

Typical Flow of Execution Determine what the user wants to do. Prepare the response. Perform the business logic. Display the results. Controller View Model Layout

What Does a Model Look Like Class that extends Joomla's JModel Your method representing business logic model.php

Class that extends Joomla's JModel

Your method representing business logic

View from the Frontend index.php?option=com_hello

index.php?option=com_hello

Modification to the View Add code to fetch a specific greeting. hello.php

Add code to fetch a specific greeting.

View from the Frontend 2 index.php?option=com_hello&id=2 Our presentation logic has not changed.

index.php?option=com_hello&id=2

Quick Review So far we've learned that: A component typically consists of a model, view, and controller; A component should, but does not have to, use the MVC; and Joomla offers an API for many common resources, such as the database and request variables.

So far we've learned that:

A component typically consists of a model, view, and controller;

A component should, but does not have to, use the MVC; and

Joomla offers an API for many common resources, such as the database and request variables.

Displaying Data We still need to display the data. That is where the views and the layout files come in. Generally speaking, models are accessed from the view class, not the layout files, but either style works.

We still need to display the data. That is where the views and the layout files come in.

Generally speaking, models are accessed from the view class, not the layout files, but either style works.

Accessing the Business Logic The method getGreeting() is called from the view class. view.html.php

The method getGreeting() is called from the view class.

Modifying the Presentation Logic The view contains the logic for displaying the data.

The view contains the logic for displaying the data.

Layout Files Layout files are used to display the data. Your template files should be the few that contain HTML. nogreeting.php default.php

Layout files are used to display the data. Your template files should be the few that contain HTML.

Quick Review Now we know that: Models represent business logic; Views represent presentation logic; Layouts are for markup language.

Now we know that:

Models represent business logic;

Views represent presentation logic;

Layouts are for markup language.

Controller tasks You may not need to customize your controller because Joomla provides most of the control logic for you. However you can define your own methods if you want. You may want to throw an error if the use is not logged in.

You may not need to customize your controller because Joomla provides most of the control logic for you. However you can define your own methods if you want.

You may want to throw an error if the use is not logged in.

Customizing the Controller controller.php

Using Controller Methods index.php?option=com_hello&task=showGreeting

index.php?option=com_hello&task=showGreeting

Abstract Programming Interface Important APIs that we've seen. MVC - JController, JModel, JView Language - JText Input - JRequest User - JUser

Important APIs that we've seen.

MVC - JController, JModel, JView

Language - JText

Input - JRequest

User - JUser

Other Factory Resources JFactory - Source for “global” objects JApplication - The current application JMail - Mailer object JSession - Information about the current session

Other Factory Resources

JFactory - Source for “global” objects

JApplication - The current application

JMail - Mailer object

JSession - Information about the current session

Conclusion The important concepts to take away are: Controllers represent control logic; Models represent business logic; Views represent presentation logic; Layouts are for markup language. Joomla 1.5 provides new facilities for you to easily represent your business logic using a custom component.

The important concepts to take away are:

Controllers represent control logic;

Models represent business logic;

Views represent presentation logic;

Layouts are for markup language.

Joomla 1.5 provides new facilities for you to easily represent your business logic using a custom component.