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- Herausgeber: Packt Publishing
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
In Detail
TYPO3 is the enterprise-level content management system for the Web. It is large, feature-rich and very flexible, a lot of this flexibility comes through extensions written by the community. Extensions make it possible to use TYPO3 to drive any type of website, including e-commerce, blogs, social networks, catalogs, and many more. TYPO3 can be completely customized using extensions; however creating an extension can be a challenging task.
This book describes TYPO3 extension creation as it should be done. It starts from an overview of the TYPO3 API and provides recommendations on when and how to use this extensive API. Next it describes the TYPO3 extension generation process. It covers all generation options and emphasizes important decisions that extension developers should be aware of.
Since front-end plugins are the most popular TYPO3 extension type, the book has a chapter dedicated to the process of programming front-end plugins. We then move on to back-end plugin programming. All chapters stress best practices and come with unique tips from the author, who wants his experience to be shared with the TYPO3 community. The book finishes with a chapter about improving code and writing documentation.
This is the first book in English to cover TYPO3 extension development in detail. The author is a member of the TYPO3 core team and developer of many popular TYPO3 extensions. Both novice and experienced TYPO3 programmers can use this book to build the extension they need, following best practices, and saving a lot of time that would otherwise have been spent pouring though the documentation.
Approach
The book is structured so that following the chapters in order builds a TYPO3 extension from the ground up. Experienced developers can use individual chapters independently to get only the information that they need.
Each chapter is divided so that the first part contains a description and discussion of the topic covered followed by a coding example with explanation of how principles and techniques from the first part are followed in the code.
The reader is encouraged not only to read the book but also to look into the discussed classes and actually code the extension while reading the book.
Who this book is for
This book is for PHP developers who want to develop a TYPO3 extension. It assumes the reader has experience with PHP, XML, and HTML. No prior knowledge about TYPO3 extension programming or the TYPO3 API is presumed.
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Seitenzahl: 267
Veröffentlichungsjahr: 2008
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Table of Contents
TYPO3 Extension Development
Dmitry Dulepov
TYPO3 Extension Development
Copyright © 2008 Packt Publishing
All rights reserved. No part of this book may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, without the prior written permission of the publisher, except in the case of brief quotations embedded in critical articles or reviews.
Every effort has been made in the preparation of this book to ensure the accuracy of the information presented. However, the information contained in this book is sold without warranty, either express or implied. Neither the author(s), Packt Publishing, nor its dealers or distributors will be held liable for any damages caused or alleged to be caused directly or indirectly by this book.
Packt Publishing has endeavored to provide trademark information about all the companies and products mentioned in this book by the appropriate use of capitals. However, Packt Publishing cannot guarantee the accuracy of this information.
First published: September 2008
Production Reference: 1190908
Published by Packt Publishing Ltd.
32 Lincoln Road
Olton
Birmingham, B27 6PA, UK.
ISBN 978-1-847192-12-7
www.packtpub.com
Cover Image by Vinayak Chittar (<[email protected]>)
Credits
Author
Dmitry Dulepov
Reviewer
Ingo Renner
Acquisition Editor
Adil Ahmed
Development Editor
Nikhil Bangera
Technical Editor
Dhiraj Bellani
Copy Editor
Sumathi Sridhar
Editorial Team Leader
Mithil Kulkarni
Project Manager
Abhijeet Deobhakta
Project Coordinator
Rajashree Hamine
Indexers
Rekha Nair
Monica Ajmera
Proofreader
Angie Butcher
Production Coordinators
Aparna Bhagat
Rajni Thorat
Cover Designer
Aparna Bhagat
About the Author
Dmitry Dulepov is a TYPO3 core team member and developer of several popular extensions (such as RealURL, TemplaVoila, comments, ratings, and others). He is known by his active support of the TYPO3 community through TYPO3 mailing lists. In 2008 Dmitry won the contest to appear on the first TYPO3 playing cards. He runs a popular blog where he regularly publishes original tips and articles about various TYPO3 features. In addition to his continuous TYPO3 core and extension development, Dmitry provides support for the TYPO3 translation team on behalf of the core team.
The author would like to thank everyone who helped with the book. This includes but is not limited to:
The author is sure that the book will be useful to the reader and hopes to see more great extensions from the readers of the book soon.
About the Reviewer
Ingo Renner has been active in the TYPO3 project for about five years now. He started contributing to the project with a table-less template for the popular news extension "tt_news". Since then he has been active in many other areas including the content rendering group, digital asset management project, and the core team. Besides that, he's also known as a co-development leader for tt_news, current maintainer of tt_address, and lead developer for TYPO3's blog extension TIMTAB. In 2007, he joined the core team and was suddenly charged with the role of the release manager for TYPO3 4.2 - TYPO3's recent release. In March 2008, he graduated from the University of Applied Sciences, Darmstadt, with a Master of Science in Computer Science.
Ingo is a freelancer specialized in TYPO3 core development and always looking for interesting projects to improve the TYPO3 core.
Preface
This is the first book in English to cover TYPO3 extension development in detail. The author is a member of the TYPO3 core team and developer of many popular TYPO3 extensions. Both novice and experienced TYPO3 programmers can use this book to build the extension they need following best practices and saving a lot of time that would otherwise have been spent pouring though the documentation.
The book is structured so that following the chapters in order builds a TYPO3 extension from the ground up. Experienced developers can use individual chapters independently to get only the information that they need.
Each chapter is divided so that the first part contains a description and discussion of the topic covered followed by a coding example with an explanation of how principles and techniques from the first part are followed in the code.
The reader is encouraged not only to read the book but also to look into the discussed classes and actually code the extension while reading the book.
What This Book Covers
Chapter 1 gives an overview of the TYPO3 API and tells about the most important classes in TYPO3.
Chapter 2 describes files in the TYPO3 extension, what role they play and how to use them.
Chapter 3 focuses on planning. Planning makes extensions better. It makes the project successful.
Chapter 4 walks the reader through the process of extension generation. All options are explained, several issues are pointed out, and useful tips provided.
Chapter 5 focuses on the Frontend plugin theory. It also provides a lot of tips to make extensions effective.
Chapter 6 is dedicated to practical progamming. The reader will see how to make list, search, and single views, use AJAX from the Frontend plugin, and create useful TypoScript for the plugin.
Chapter 7 focuses on the Backend module programming.
Chapter 8 describes how to write documentation for the extension and polish the code before releasing it to TER.
What You Need for This Book
The author assumes that the reader has the following knowledge:
Who is This Book For
This book is for PHP developers who want to develop a TYPO3 extension. It assumes the reader has experience with PHP, XML, and HTML. No prior knowledge about TYPO3 extension programming or the TYPO3 API is presumed.
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Downloading the Example Code for the Book
Visit http://www.packtpub.com/files/code/2127_Code.zip to directly download the example code.
Note
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Errata
Although we have taken every care to ensure the accuracy of our contents, mistakes do happen. If you find a mistake in one of our books—maybe a mistake in text or code—we would be grateful if you would report this to us. By doing this you can save other readers from frustration, and help to improve subsequent versions of this book. If you find any errata, report them by visiting http://www.packtpub.com/support, selecting your book, clicking on the let us know link, and entering the details of your errata. Once your errata are verified, your submission will be accepted and the errata added to the list of existing errata. The existing errata can be viewed by selecting your title from http://www.packtpub.com/support.
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Questions
You can contact us at <[email protected]> if you are having a problem with some aspect of the book, and we will do our best to address it.
Chapter 1. About TYPO3 API
Let's get a picture of TYPO3 API before we start to talk about extension creation. There are a lot of files, functions, and function groups in TYPO3 API. Beginners can easily miss the function they should use in a particular part of the code.
This chapter is going to discuss TYPO3 API. We will not go into the details, but will provide pointers to where developers can look. The best way to read this chapter is to keep a copy of each discussed PHP file and read function description inside that file along with the description mentioned in the book.
After completing this chapter, the reader will have a general picture of TYPO3 API, and will be able to find the necessary functions in the API.
Overview of TYPO3 API
TYPO3 is a large system with lots of PHP classes. Trying to learn each class in order to learn the API is time consuming, and will not provide an understanding of the system as a whole. It is much easier to logically split the system into blocks and look at the API from this perspective.
As seen from the user experience, TYPO3 has two main parts: the Frontend (or FE) and the Backend (or BE). Website visitors see the FE of TYPO3. Website editors create and modify the website content from the BE of TYPO3.
The TYPO3 API can be divided approximately the same way: FE API and BE API. The FE API includes classes to create website output, while the BE API includes classes for content manipulation and other functionality to help editors do their work in an effective way. Extensions can extend existing or add new APIs to the system. One of the best examples is TemplaVoila. It adds point-and-click templates to the TYPO3 BE and flexible content elements to the FE.
However, there is one more part, which is not visible to website visitors or editors but used by both FE and BE API. There is no name for it in TYPO3. In this book, we will call it the Common API. An example of such an API is the database API. It would be wrong to use different database layers for BE and FE (otherwise programmers would have to learn more APIs and would tend to use the one most convenient instead of the one "assigned" to Backend or Frontend). So, TYPO3 has only one layer that works with the database. All system classes and extensions are expected to use this API to access and retrieve data from the database.
While we can logically separate the TYPO3 API into three parts, it should be noted that most TYPO3 classes and functions have a very long history. They are constantly updated, but their age is still visible. Most classes are in the same file system directory (t3lib), and it is hard to tell where the class really belongs just by looking at its name. However, this applies only to the file system. Generally, these classes include functions for a single API group only. So logically, they are well-designed and separated from other groups.
The TYPO3 core team makes every effort to keep the API clear, logical, and effective. Extension developers can learn a lot about TYPO3 by looking into the implementation of the TYPO3 API while programming extensions. This is really a good way to become a TYPO3 professional.
In the following sections, we will look at each API group and certain classes inside them. Due to the large number of API classes, it is not possible to cover them all. It would take the whole book alone to cover them all. So, we are going to cover only those classes that extension developers will most likely meet or use during extension development. We are going to start with the most basic and universal classes and move on to more specialized classes. Note that this chapter will provide only an overview of the API, and not a detailed description of each function. We will look deeper into many of these classes later in the book.
But first, we need to discuss certain basic issues about TYPO3 from a developer's view.
PHP Classes and Files
There are certain conventions concerning file and class naming in TYPO3. They must be used in extensions too and knowing these conventions helps to locate files quickly.
Each class file starts with class. and is followed by a class name in lower case. The file ends with a .php extension. There are certain exceptions to this rule, and they will be described in this book. These exceptions exist due to historical reasons, and no new class may become an exception.
Classes have a certain prefix that declares where they belong in the TYPO3 class hierarchy. The following system prefixes are defined:
Each prefix corresponds to a "library" if it ends with "lib_", and to a "namespace" otherwise. "Library" is just a way to say that a "namespace" belongs to TYPO3. In other words, library classes are TYPO3 classes. Extensions cannot introduce new library classes.
t3lib_
t3lib stands for "TYPO3 library". This name is historical, and everyone just calls it t3lib (tee-three-lib). t3lib is the largest collection of classes in TYPO3. It includes most Common, FE, and BE classes. It is easy to say that a class belongs to t3lib by looking at its name. Here are some examples:
We will look at some t3lib classes later in this chapter.
tslib_
tslib stands for "TypoScript Library", The name has historical reasons as well and everyone calls this library tslib (tee-es-lib). It is located in the typo3/sysext/cms/tslib directory (inside the cms system extension). Most of these classes are already included when code runs in FE. So there is no need to include them explicitly in extensions.
The library classes are responsible for the rendering of the website and most of the FE logic. The base class for FE plugins (modules that extend TYPO3 Frontend functionality) is also located here.
We will discuss tslib classes in the Frontend API section.
Here is a list of some classes in tslib:
This is the main FE class in TYPO3. It represents a page that a website visitor sees in the browser. There is only one instance of this class in TYPO3 FE, and it is available as and generally referred as "TSFE".
tslib_cobjThis is one of the exclusions to generic naming rule mentioned earlier. This class is located in the file named class.tslib_content.php, but the class name is different. This class implements content objects. Content objects is a TYPO3 way of generating different types of content. There are many content objects, for example, TEXT, IMAGE, or HMENU. They are the same content objects as found in TypoScript. FE plugins from extensions are USER or USER_INT content objects. Instances of this class can either be created directly (see later in this chapter), or by calling .
tslib_fetceThis is an attempt to bring some BE functions (such as clear_cacheCmd) to the FE. While this class exists, it is not really updated and should not be used.
tslib_feuserauthThis is an internal class that authenticates website visitors ("Frontend users"). This class is created and used by TSFE. An instance of this class is always available as .
tslib_pibaseThis is a base class for FE plugins. We will cover it in detail in Chapter 5.
tx_
This namespace is reserved for extensions ("tx" stands for "TYPO3 Extensions"). All extension classes must begin with tx_ (with the exception of "ux" classes).
ux_
This namespace is reserved for XCLASSes. XCLASS is a way to subclass a class in TYPO3 and make use of the subclass instead of the parent class in a way that is transparent to all the other classes in the system. Normally, XCLASSes are provided by extensions. XCLASSes take the class and file name of the parent class but prepend it with ux_, as in class.ux_tslib_fe.php or class.ux_t3lib_tcemain.php.
While XCLASSes may seem the easiest way to modify system behavior, they should be avoided and used only if there is absolutely no other way to change system behavior. The fundamental limitations of XCLASSes is that there can be only one XCLASS for a given class in the system. If two extensions try to XCLASS the same class, only the last one will succeed.
user_
This namespace is reserved for PHP functions outside of a class. TYPO3 will refuse to call any function outside of a class that is not prefixed with user_. If an extension key has this prefix, it means that the extension is private. Such extensions cannot be sent to the TYPO3 Extension Repository. Typically, such extensions are created for testing purposes.
How Data Is Stored in TYPO3
TYPO3 uses a database (typically MySQL) and the file system to store data. The file system keeps configuration files, some cache files, images, and uploaded files. The database stores pages, content elements, and lots of system data (such as TypoScript templates, logs, and so on).
All (to be precise most, but for our purpose, all) tables in TYPO3 roughly follow the same structure. They have a set of predefined (reserved) fields. TYPO3 will not work properly if one or more of the required fields is missing. Examples of predefined fields are uid (unique identifier of the record), pid (id of the page where this record is located), crdate (record creation time), tstamp (last update time), cruser_id (uid of the Backend user, who created this record). A table may also contain other reserved fields. If it does, TYPO3 will automatically provide additional functionality for the table. The best examples of such fields are deleted (indicates whether a record is deleted), starttime (indicates when a record becomes visible in the FE), endtime (indicates when a record stops being visible), and hidden (indicates whether a record is hidden). There are other fields, which will be discussed later. All these fields are managed by the system, and extensions usually do not change them.
TYPO3 comes with several default tables. These main tables are:
The pages table stores page data (uid, title, and so on), while the pages_language_overlay table stores translations of the page data.
tt_contentThis table stores information about content elements. This is usually one of the largest tables in the system.
be_*This table stores information related to BE users.
cache_*This table stores cache data.
fe_*This table stores information related to FE users.
sys_*This tables stores various system data.
tx_*This table stores tables from extensions.
If an extension provides a new table, it must ensure that the table name has a certain format. The table name must start with tx_, followed first by the extension key without underscores and next by an underscore, and the table name. For example, an extension with the extension key my_ext can have the following valid table names:
The following table names are not valid:
We will discuss tables in more detail when we generate extensions later in this book. At the moment, it is important to remember two things:
