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- Herausgeber: Packt Publishing
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
CodeIgniter (CI) is a powerful open-source PHP framework with a very small footprint, built for PHP coders who need a simple and elegant toolkit to create full-featured web applications. CodeIgniter is an MVC framework, similar in some ways to the Rails framework for Ruby, and is designed to enable, not overwhelm.
This book explains how to work with CodeIgniter in a clear logical way. It is not a detailed guide to the syntax of CodeIgniter, but makes an ideal complement to the existing online CodeIgniter user guide, helping you grasp the bigger picture and bringing together many ideas to get your application development started as smoothly as possible.
This book will start you from the basics, installing CodeIgniter, understanding its structure and the MVC pattern. You will also learn how to use some of the most important CodeIgniter libraries and helpers, upload it to a shared server, and take care of the most common problems. If you are new to CodeIgniter, this book will guide you from bottom to top. If you are an experienced developer or already know about CodeIgniter, here you will find ideas and code examples to compare to your own.
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Seitenzahl: 354
Veröffentlichungsjahr: 2009
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Table of Contents
CodeIgniter 1.7
David Upton
Jose Argudo
CodeIgniter 1.7
Copyright © 2009 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 authors, 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: November 2009
Production Reference: 1031109
Published by Packt Publishing Ltd.
32 Lincoln Road
Olton
Birmingham, B27 6PA, UK.
ISBN: 978-1-847199-48-5
www.packtpub.com
Cover Image by Vinayak Chittar (<[email protected]>)
Credits
Authors
Jose Argudo Blanco
David Upton
Reviewer
Pascal Kriete
Acquisition Editor
Douglas Paterson
Development Editor
Swapna Verlekar
Technical Editor
Dhwani Devater
Indexer
Hemangini Bari
Editorial Team Leader
Abhijeet Deobhakta
Project Team Leader
Lata Basantani
Project Coordinator
Poorvi Nair
Proofreader
Chris Smith
Graphics
Nilesh R Mohite
Production Coordinator
Dolly Dasilva
Cover Work
Dolly Dasilva
About the Authors
Jose Argudo Blanco is a web developer from Valencia, Spain. After finishing his studies he started working for a web design company. After working for six years for that company and some others, he decided to work as a freelance.
Now, after some years have passed, he thinks it's the best decision he has ever taken—a decision that let him work with the tools he likes, such as CodeIgniter, Joomla!, CakePHP, JQuery, and other well-known open source technologies.
For the past few months he has also reviewed some books for Packt Publishing, such as Magento 1.3 Theme Design, Magento: Beginner's Guide, Joomla! 1.5 SEO, Symfony 1.3 Web Application Development, and Joomla! with Flash. The one yet to be published is Magento Development with PHP.
He has put a lot of effort into this book and hopes it's very useful for the readers.
To my girlfriend Silvia whose support helps me every day, to my brother, maybe some day we will work together, to my parents for being always there, and, of course, to Swapna, Poorvi, and all the Packt team, without their help, and Pascal's advices this book couldn't have been possible.
David Upton is a director of a specialized management consultancy company, based in London but working around the world. His clients include some of the world's largest companies. He is increasingly interested in web-enabling his work, and seeking to turn ideas into robust professional applications by the simplest and easiest route. So far he has written applications for two major companies in the UK. His other interests include simulation, on which he writes a weblog that takes up far too much of his time, and thinking.
About the Reviewer
Pascal Kriete is a developer from Germany. Although his background lies in engineering, after a short, unsuccessful stint in traditional server/client administration he found his way into freelance web development. Looking to streamline his development workflow—as freelancers want to do—he discovered CodeIgniter and began actively participating in the community. This involvement quickly spread to the ExpressionEngine forums and by the end of 2008 Pascal joined the EllisLab team as a Technical Support Specialist. He has since moved on to become a member of the development team, where he continues to polish code and gets to interact with an ever growing number of third-party developers.
Preface
CodeIgniter (CI) is a powerful open source PHP framework with a very small footprint, built for PHP programmers who need a simple and elegant toolkit to create full-featured web applications. CodeIgniter is an MVC framework, similar in some ways to the Rails framework for Ruby, and is designed to enable, not overwhelm. This book explains how to work with CodeIgniter in a clear logical way.
What this book covers
Chapter 1: Introduction to CodeIgniter, will introduce you to what frameworks are, and specifically we will talk about CI and how it can help in our day to day work. We will see what CI offers and what it doesn't.
Chapter 2: Setting up a CodeIgniter Site, will help you to prepare the basic configuration of your site, studying CI's structure and config files. At the end you will have a working CI installation.
Chapter 3: Navigating Your Site, will cover some important topics, like the MVC pattern and how CI handles this pattern, and we will make an example controller just to see how all this works.
Chapter 4: Using CI to Simplify Databases, helps you to start working with databases. This is a very important topic. CI will really help us at this point, so we are going to see in detail all the tools at our disposal, including Active Record.
Chapter 5: Simplifying HTML Pages and Forms, will help you with HTML and form helpers, which are some important tools you will find in CodeIgniter; we will see some examples about their usage and introduce form validation.
Chapter 6: Simplifying Sessions and Security, will cover some important security features of CI, which will help make your site more secure. As we will also talk about sessions we will build a simple login feature.
Chapter 7: CodeIgniter and Objects, introduces a bit on object-oriented programming and how CI makes use of it, including the use of the CI super object, and how we can modify and use it.
Chapter 8: Improving Our Application with Third-Party Code, will help you take some rest from the hard work you have done in the previous chapters. We will see some third-party code that we can easily add to our site, improving it, and adding interesting functionalities.
Chapter 9: Using CI to Communicate, explains how CI helps us in communication. Communication is an important part of every site. We will see the ftp class, email class, and XML-RPC class and, of course, the possibility to add more as we need!
Chapter 10: How CI Helps to Provide Dynamic Information, will show some more useful helpers and classes, this will include the date helper, text helper, and table and language classes. All of this will help in the development of our site, not only in reducing code, but in adding powerful features to our working toolbox.
Chapter 11: Using CI to Handle Files and Images, will be about files, uploading, downloading, and compressing them, of course, all with CI classes! As always those classes will make our life easier. Image treatment also has some space in the chapter as CI has some nice features to crop, reduce, watermark, and so on.
Chapter 12: Moving Your Site to the WWW, will finally show you how to upload your site to a shared host or similar. Here we will see in detail how to do that, and also what kind of error we can expect to encounter.
Chapter 13: CRUD—or Putting It All Together, will be a chapter of "putting it all together", where we'll take time to recap and emphasize the most important topics covered to the moment. Insert, edit, and remove records from the database are some topics we will see here, but also ordering and pagination of results.
Chapter 14: The Verdict on CI, will summarize the key points of CI, not to forget anything, as every little thing CI offers will be of great help.
Chapter 15: Resources and Extensions, will give a list of resources and third-party code—we don't want to reinvent the wheel! We will take a look at some useful extensions such as authentication, PDF generation, invoicing, and much more.
The Appendix will introduce a new and interesting CI feature, the cart class; building a store has never been easier!
What you need for this book
Only basic PHP and HTML knowledge is needed to understand this book. All the rest is explained here from top to bottom. You won't get lost!
Who this book is for
This book is not only for PHP developers who want to be more productive at work, but also for those who are new to web programming and are searching for a useful tool that helps in their work. If you are tired of writing the same code again and again, this book is for you. If you want to create more robust and easier-to-maintain PHP sites, again this book is for you. But this book is really for you if you want to enjoy PHP programming with a framework that really helps you.
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Downloading the example code for the book
Visit http://www.packtpub.com/files/code/9485_Code.zip to directly download the example code.
Note
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Errata
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Questions
You can contact us at <[email protected]> if you are having a problem with any aspect of the book, and we will do our best to address it.
What CI doesn't do
There are some things that CI doesn't do. CI was intended to be a small and lightweight framework. The zipped download for version 1.7.2 is only 2.1 MB and is downloaded in seconds, whereas the Zend framework is 10 MB. It won't answer all the problems you will have. But it does:
As a result of being lightweight, it does not have as many features as some of its rivals. Other frameworks such as Rails, CakePHP, or Symfony have scaffolding and generators. These tools automatically write certain basic scripts for you.
Once you have set up a database, Rails creates out-of-the-box web pages to do basic Create, Read, Update, and Delete (CRUD) operations on the database tables. In addition, Rails allows you to write generators—pieces of code that automatically write other basic scripts. The Rails community has created quite a lot of these, so you can automatically generate scripts that do all sorts of clever things.
CI concentrates on making basic things easy. Some of the things it handles are:
Sounds familiar? All of these are basic processes, which you will have to go through if you're building a dynamic website. CI makes these processes easier, and makes your code more likely to work. Join this outstanding community; it will help you in case you need it (at the CodeIgniter forums). You can even share code at the Wiki (http://codeigniter.com/wiki/), and you will find why CI is so popular.
Yes, but…what is CodeIgniter? What are frameworks?
Shortly after programming was invented, it was noticed that it involved many repetitive operations. And maybe shortly after that, Ada Lovelace—spanner in hand adjusting Babbage's differential engine—or Alan Turing at Bletchley Park decided to modularize code. So, you only had to write certain chunks once, and could then reuse them. PHP programmers are used to writing separate chunks of code in functions, and then storing those functions in include files.
At one level, a framework is just that—lot of chunks of code stored in separate files, which simplify the coding of repetitive operations. In the previous examples, connecting to the database or building HTML form elements are abstracted and simplified for you. You call a function in the framework, which is easy to handle than the original code.
It goes beyond that. Writing code involves continuous choices between the many ways of tackling the same problem. Most frameworks impose a set of choices on you. They've started to handle the problem one way, so you have to go that way as well. If they are sensible choices, it makes your life much simpler. If not, it's like trying to write a sales brochure using Excel, or showing cash flow projections using Word. Both can probably be done, but neither is the best use of your time.
Sensible design decisions make sure that the things you need are accessible, but prevent them from spilling over into each other. A good framework makes these decisions for you—starting off with a sensible foundation for your program and guiding you through the next steps.
A framework will also improve team programming. As every developer has to adhere to the framework syntax and structure, it is an important part of software maintainability. The code you write today needs to be readable by other people in future. Imagine you arrive to a new workplace and then you inherit a couple of projects. In a perfect world those projects would be well commented, but reality usually hits... Wouldn't it be nice to have a central resource of documentation to get started with those projects?
Most frameworks will offer good documentation. CI isn't an exception; everything is well documented—functions, structures, conventions. You won't have to imagine what a certain function does, you will know it. A very good starting point, don't you think?
Nowadays there are lot of frameworks out there, not only PHP frameworks but Ruby frameworks, Python frameworks, and so on. For PHP programmers there are hundreds of options (well, may not be hundreds, but if we do search for PHP frameworks the results will be overwhelming). Of all these options there are some that are more popular; CI is among them, with others such as CakePHP, Zend Framework, Symfony, and more.
As you are reading this book, you are interested in PHP frameworks, especially CodeIgniter, so we will keep to it.
If you take a look at http://phpframeworks.com/ and http://www.phpframeworks.com/top-10-php-frameworks/, you will see how well CodeIgniter is doing. CI is very popular as a PHP framework; with this book you will know, why. Also if you look at some forums and blogs you'll notice that postings get very heated about which framework is the best. The truth seems to be that each has its strengths, and none is without its own weaknesses. In time you will learn to decide which framework to use in which project. It is recommended that you should think about which tool to use, before starting your projects. Choose the one that will help you to end with a well done project, in good time, and with the best possible scalability. Most of the times CI helps achieve this.
Comparing CI to other open source solutions (CakePHP and Joomla!)
For one reason or another one should compare these three most of the time and, of course, use one of them. There are other solutions out there, as we have commented before, "few" is not the word to describe PHP frameworks.
Though you would like to have Zend Framework and Symfony in your toolbox, for now, let's use these three for comparison. For example, when Jose heard about frameworks it was all about Ruby on Rails. Before that he used to write his own code for every project. Though Ruby on Rails is a very good framework, for him—a PHP programmer at heart—that was not the solution.
Searching for a PHP framework that was similar to Ruby on Rails, but PHP made, CakePHP was one option. It was quite similar in concept to Ruby on Rails, it also had the same convention-driven architecture that you need to learn before using it. It will pay-back with lots of functionality, automation, and more. But keep in mind that the learning curve is steeper than CodeIgniter's.
Using CakePHP requires you to adhere to some strict conventions (those can be changed but the out-of-the-box software comes with them). Most of the time they are naming conventions, but there are database conventions also.
After some time, because of curiosity, in spite of incredible lack of learning time (some nearby shouting boss also helped), continuing research of PHP frameworks found CodeIgniter. The most convincing thing was the documentation (CakePHP wasn't as well documented as it is today).
CI has less conventions, and minimal configuration, also you can forget about most of them and work as you have always done. You don't want to use models, and you don't have to (though it is recommended). That said, one of the strengths of CI is just that—download it and start programming.
Joomla! is not exactly a framework, it helps you build websites faster. Also in the latest versions it has turned into the MVC (Model-View-Controller) pattern. The good part of Joomla! is that it is a CMS (Content Management System), but I think it is also its bad part, as sometimes you just don't need so much as Joomla! has to offer. Of course you can develop your own solution over Joomla!, but then what's the point of using Joomla!, and not using what it has to offer?
CI, usually, is the most well-balanced of the three, but let's see how we can choose one of them.
What to choose
With all those options out there, why should you go with CI? The answer—it's not that easy and involves, in most cases, personal preference. There will be projects that will be better suited to one of the other two options. Let's see some examples that will guide us.
When to choose Joomla!
When to choose CakePHP
When to choose CodeIgniter
Most of the time we will be using CI because it is very flexible. If you like programming CI will help you in doing it. It will seem as if CI isn't even there. You realize it only when you look at the time you are gaining and the better structure of your project.
If you are new to frameworks it is recommended that you get CI, maybe later you use another one (probably both of them), but CI will always have a place in your heart.
Note
Packt Publishing has books on some other frameworks and Joomla!. It is recommended to read them, it will give you a broader view of things.
For books on Joomla visit http://www.packtpub.com/joomla-version-1-5/book.
For books on CakePHP visit http://www.packtpub.com/cakephp-application-development/book.
License
If you are building a commercial application, the license terms for any software you are using become critical. If you are raising venture capital, expect the VC's lawyers to go over them in detail. With CI this is not a problem. It has a very generous license that is downloaded with your files.
Unlike some commercial software, CI's license even fits on one screen. Here it is, in the following screenshot:
Summary
If you already know some PHP and are designing intelligent websites, the CodeIgniter framework is all about making your life easier. It helps you to:
There are quite a lot of frameworks and all of them offer chunks of pre-written code that make the repetitive or complex processes of coding easier and not just for the PHP language. They impose a helpful structure on your site's development.
This book does not make any comparisons between frameworks. CI works for most, and we will see, how and why. It will be useful for you too, and you will be able to save much time and, as a result, enjoy the coding process more.
This book takes you through some of the framework's main features, and tries to explain some of what goes on "under the hood". We've used a real-world example for the code illustrations in this book to show that CI is a serious tool that can be quickly and easily used in a demanding environment.
Enjoy!
Chapter 2. Setting up a CodeIgniter Site
Setting up the CI package on your web server or a local machine is easy. This chapter explains, what happens when you install the site and which files will be created. Let's look at:
