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- Herausgeber: Packt Publishing
- Kategorie: Wissenschaft und neue Technologien
- Sprache: Englisch
Learn the art of PHP programming through this example-rich book filled to the brim with tutorials every PHP developer needs to know
About This Book
- Set up the PHP environment and get started with web programming
- Leverage the potential of PHP for server-side programming, memory management, and object-oriented programming (OOP)
- This book is packed with real-life examples to help you implement the concepts as you learn
Who This Book Is For
If you are a web developer or programmer who wants to create real-life web applications using PHP 7, or a beginner who wants to get started with PHP 7 programming, this book is for you. Prior knowledge of PHP, PHP 7, or programming is not mandatory.
What You Will Learn
- Set up a server on your machine with PHP
- Use PHP syntax with the built-in server to create apps
- Apply the OOP paradigm to PHP to write richer code
- Use MySQL to manage data in your web applications
- Create a web application from scratch using MVC
- Add tests to your web application and write testable code
- Use an existing PHP framework to build and manage your applications
- Build REST APIs for your PHP applications
- Test the behavior of web applications with Behat
In Detail
PHP is a great language for building web applications. It is essentially a server-side scripting language that is also used for general purpose programming. PHP 7 is the latest version with a host of new features, and it provides major backwards-compatibility breaks.
This book begins with the fundamentals of PHP programming by covering the basic concepts such as variables, functions, class, and objects. You will set up PHP server on your machine and learn to read and write procedural PHP code. After getting an understanding of OOP as a paradigm, you will execute MySQL queries on your database. Moving on, you will find out how to use MVC to create applications from scratch and add tests. Then, you will build REST APIs and perform behavioral tests on your applications.
By the end of the book, you will have the skills required to read and write files, debug, test, and work with MySQL.
Style and approach
This book begins with the basics that all PHP developers use every day and then dives deep into detailed concepts and tricks to help you speed through development. You will be able to learn the concepts by performing practical tasks and implementing them in your daily activities, all at your own pace.
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Veröffentlichungsjahr: 2016
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Table of Contents
Learning PHP 7
Learning PHP 7
Copyright © 2016 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, nor Packt Publishing, and its dealers and 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 of 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: March 2016
Production reference: 1210316
Published by Packt Publishing Ltd.
Livery Place
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Birmingham B3 2PB, UK.
ISBN 978-1-78588-054-4
www.packtpub.com
Credits
Author
Antonio Lopez
Reviewer
Brad Bonkoski
Commissioning Editor
Kunal Parikh
Acquisition Editors
Nikhil Karkal
Divya Poojari
Content Development Editor
Rohit Kumar Singh
Technical Editor
Taabish Khan
Copy Editors
Shruti Iyer
Sonia Mathur
Project Coordinator
Izzat Contractor
Proofreader
Safis Editing
Indexer
Tejal Daruwale Soni
Production Coordinator
Melwyn D'sa
Cover Work
Melwyn D'sa
About the Author
Antonio Lopez is a software engineer with more than 7 years of experience. He has worked with PHP since university, which was 10 years ago, building small personal projects. Later, Antonio started his journey around Europe, working in Barcelona, London, Dublin, and back in Barcelona. He has worked in a number of different areas, from web applications to REST APIs and internal tools. Antonio likes to spend his spare time on personal projects and start-ups and has a strong vocation in education and teaching.
I would like to give thanks to my wife, Neri, for supporting me through the whole process of writing this book without going crazy.
About the Reviewer
Brad Bonkoski has been developing software for over 15 years, specializing in internal operations, systems, tools, and automation. Sometimes, this role is loosely referred to as DevOps. He leans more toward the Dev side of this misunderstood buzzword. After building an incident management system and managing change management for Yahoo, Brad became motivated by metrics and now lives by the mantra that what doesn't get measured doesn't get fixed. Today, he greases the wheels of productivity for Shazam.
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Preface
There is no need to state how much weight web applications have in our lives. We use web applications to know what our friends are doing, to get the latest news about politics, to check the results of our favorite football team in a game, or graduate from an online university. And as you are holding this book, you already know that building these applications is not a job that only a selected group of geniuses can perform, and that it's rather the opposite.
There isn't only one way to build web applications; there are actually quite a lot of languages and technologies with the sole purpose of doing this. However, if there is one language that stands out from the rest, either historically or because it is extremely easy to use, it is PHP and all the tools of its ecosystem.
The Internet is full of resources that detail how to use PHP, so why bother reading this book? That's easy. We will not give you the full documentation of PHP as the official website does. Our goal is not that you get a PHP certification, but rather to teach you what you really need in order to build web applications by yourself. From the very beginning, we will use all the information provided in order to build applications, so you can note why each piece of information is useful.
However, we will not stop here. Not only will we show you what the language offers you, but also we will discuss the best approaches to writing code. You will learn all the techniques that any web developer has to master, from OOP and design patterns such as MVC, to testing. You will even work with the existing PHP frameworks that big and small companies use for their own projects.
In short, you will start a journey in which you will learn how to master web development rather than how to master a programming language. We hope you enjoy it.
What this book covers
Chapter 1, Setting Up the Environment, will guide you through the installation of the different software needed.
Chapter 2, Web Applications with PHP, will be an introduction to what web applications are and how they work internally.
Chapter 3, Understanding PHP Basics, will go through the basic elements of the PHP language—from variables to control structures.
Chapter 4, Creating Clean Code with OOP, will describe how to develop web applications following the object-oriented programming paradigm.
Chapter 5, Using Databases, will explain how you can use MySQL databases in your applications.
Chapter 6, Adapting to MVC, will show how to apply the most famous web design pattern, MVC, to your applications.
Chapter 7, Testing Web Applications, will be an extensive introduction to unit testing with PHPUnit.
Chapter 8, Using Existing PHP Frameworks, will introduce you to existing PHP frameworks used by several companies and developers, such as Laravel and Silex.
Chapter 9, Building REST APIs, will explain what REST APIs are, how to use third-party ones, and how to build your own.
Chapter 10, Behavioral Testing, will introduce the concepts of continuous integration and behavioral testing with PHP and Behat.
What you need for this book
In Chapter 1, Setting Up the Environment, we will go through the details of how to install PHP and the rest of tools that you need in order to go though the examples of this book. The only thing that you need to start reading is a computer with Windows, OS X, or Linux, and an Internet connection.
Who this book is for
This book is for anyone who wishes to write web applications with PHP. You do not need to be a computer science graduate in order to understand it. In fact, we will assume that you have no knowledge at all of software development, neither with PHP nor with any other language. We will start from the very beginning so that everybody can follow the book.
Experienced readers can still take advantage of the book. You can quickly review the first chapter in order to discover the new features PHP 7 comes with, and then focus on the chapters that might interest you. You do not need to read the book from start to end, but instead keep it as a guide, in order to refresh specific topics whenever they are needed.
Conventions
In this book, you will find a number of text styles that distinguish between different kinds of information. Here are some examples of these styles and an explanation of their meaning.
Code words in text, database table names, folder names, filenames, file extensions, pathnames, dummy URLs, user input, and Twitter handles are shown as follows: "Now, create a myactions.js file with the following content."
A block of code is set as follows:
When we wish to draw your attention to a particular part of a code block, the relevant lines or items are set in bold:
Any command-line input or output is written as follows:
New terms and important words are shown in bold. Words that you see on the screen, for example, in menus or dialog boxes, appear in the text like this: "Click on Next until the end of the installation wizard."
Note
Warnings or important notes appear in a box like this.
Tip
Tips and tricks appear like this.
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Downloading the example code
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Questions
If you have a problem with any aspect of this book, you can contact us at <[email protected]>, and we will do our best to address the problem.
Setting up the environment on OS X
If you are not convinced with Vagrant and prefer to use a Mac to develop PHP applications, this is your section. Installing all the necessary tools on a Mac might be a bit tricky, depending on the version of your OS X. At the time of writing this book, Oracle has not released a MySQL client that you can use via the command line that works with El Capitan, so we will describe how to install another tool that can do a similar job.
Installing PHP
If it is the first time you are using a Mac to develop applications of any kind, you will have to start by installing Xcode. You can find this application for free on the App Store:
Another indispensable tool for Mac users is Brew. This is the package manager for OS X and will help us install PHP with almost no pain. To install it, run the following command on your command line:
If you already have Brew installed, you can make sure that everything works fine by running these two commands:
It is time to install PHP 7 using Brew. To do so, you will just need to run one command, as follows:
The result should be as shown in the following screenshot:
Make sure to add the binary to your PATH environment variable by executing this command:
You can check whether your installation was successful by asking which version of PHP your system is using with the $ php –v command.
Installing MySQL
As pointed out at the beginning of this section, MySQL is a tricky one for Mac users. You need to download the MySQL server installer and MySQL Workbench as the client. The MySQL server installer can be found at https://dev.mysql.com/downloads/mysql/. You should find a list of different options, as shown here:
The easiest way to go is to download DMG Archive. You will be asked to log in with your Oracle account; you can create one if you do not have any. After this, the download will start. As with any DMG package, just double-click on it and go through the options—in this case, just click on Next all the time. Be careful because at the end of the process, you will be prompted with a message similar to this:
Make a note of it; otherwise, you will have to reset the root password. The next one is MySQL Workbench, which you can find at http://www.mysql.com/products/workbench/. The process is the same; you will be asked to log in, and then you will get a DMG file. Click on Next until the end of the installation wizard. Once done, you can launch the application; it should look similar to this:
Installing Nginx
In order to install Nginx, we will use Brew, as we did with PHP. The command is the following:
If you want to make Nginx start every time you start your laptop, run the following command:
If you have to change the configuration of Nginx, you will find the file in /usr/local/etc/nginx/nginx.conf. You can change things, such as the port that Nginx is listening to or the root directory where your code is (the default directory is /usr/local/Cellar/nginx/1.8.1/html/). Remember to restart Nginx to apply the changes with the sudo nginx command.
Installing Composer
Installing Composer is as easy as downloading it with the curl command; move the binary to /usr/local/bin/ with the following two commands:
Setting up the environment on Windows
Even though it is not very professional to pick sides based on personal opinions, it is well known among developers how hard it can be to use Windows as a developer machine. They prove to be extremely tricky when it comes to installing all the software since the installation mode is always very different from OS X and Linux systems, and quite often, there are dependency or configuration problems. In addition, the command line has different interpreters than Unix systems, which makes things a bit more confusing. This is why most developers would recommend you use a virtual machine with Linux if you only have a Windows machine at your disposal.
However, to be fair, PHP 7 is the exception to the rule. It is surprisingly simple to install it, so if you are really comfortable with your Windows and would prefer not to use Vagrant, here you have a short explanation on how to set up your environment.
Installing PHP
In order to install PHP 7, you will first download the installer from the official website. For this, go to http://windows.php.net/download. The options should be similar to the following screenshot:
Choosex86 Thread Safe for Windows 32-bit or x64 Thread Safe for the 64-bit one. Once downloaded, uncompress it in C:\php7. Yes, that is it!
Installing MySQL
Installing MySQL is a little more complex. Download the installer from http://dev.mysql.com/downloads/installer/ and execute it. After accepting the license agreement, you will get a window similar to the following one:
For the purposes of the book—and actually for any development environment—you should go for the first option: Developer Default. Keep going forward, leaving all the default options, until you get a window similar to this:
Depending on your preferences, you can either just set a password for the root user, which is enough as it is only a development machine, or you can add an extra user by clicking on Add User. Make sure to set the correct name, password, and permissions. A user named test with administration permissions should look similar to the following screenshot:
For the rest of the installation process, you can select all the default options.
Installing Nginx
The installation for Nginx is almost identical to the PHP 7 one. First, download the ZIP file from http://nginx.org/en/download.html. At the time of writing, the versions available are as follows:
You can safely download the mainline version 1.9.10 or a later one if it is stable. Once the file is downloaded, uncompress it in C:\nginx and run the following commands to start the web server:
Installing Composer
To finish with the setup, we need to install Composer. To go for the automatic installation, just download the installer from https://getcomposer.org/Composer-Setup.exe. Once downloaded, execute it in order to install Composer on your system and to update your PATH environment variable.
Setting up the environment on Ubuntu
Setting up your environment on Ubuntu is the easiest of the three platforms. In fact, you could take the provisioner.sh script from the Setting up the environment with Vagrant section and execute it on your laptop. That should do the trick. However, just in case you already have some of the tools installed or you want to have a sense of control on what is going on, we will detail each step.
Installing PHP
The only thing to consider in this section is to remove any previous PHP versions on your system. To do so, you can run the following command:
The next step is to add the necessary repositories in order to fetch the correct PHP version. The commands to add and update them are:
Finally, we need to install PHP 7 together with the driver for MySQL. For this, just execute the following three commands:
Installing MySQL
Installing MySQL manually can be slightly different than with the Vagrant script. As we can interact with the console, we do not have to specify the root password previously; instead, we can force MySQL to prompt for it. Run the following command and keep in mind that the installer will ask you for the password:
Once done, if you need to start the MySQL server, you can do it with the following command:
Installing Nginx
The first thing that you need to know is that you can only have one web server listening on the same port. As port 80 is the default one for web applications, if you are running Apache on your Ubuntu machine, you will not be able to start an Nginx web server listening on the same port 80. To fix this, you can either change the ports for Nginx or Apache, stop Apache, or uninstall it. Either way, the installation command for Nginx is as follows:
Now, you will need to enable a site with Nginx. The sites are files under /etc/nginx/sites-available. There is already one file there, default, which you can safely replace with the following content:
This configuration basically points the root directory of your web application to the /var/www/html directory. You can choose the one that you prefer, but make sure that it has the right permissions. It also listens on the port 80, which you can change with the one you prefer; just keep this in mind that when you try to access your application via a browser. Finally, to apply all the changes, run the following command:
Tip
Downloading the example code
You can download the example code files for this book from your account at http://www.packtpub.com. If you purchased this book elsewhere, you can visit http://www.packtpub.com/support and register to have the files e-mailed directly to you.
You can download the code files by following these steps:
Once the file is downloaded, please make sure that you unzip or extract the folder using the latest version of:
Summary
In this chapter, you learned how easy it is to set up a development environment using Vagrant. If this did not convince you, you still got the chance to set up all the tools manually. Either way, now you are able to work on the next chapters.
In the next chapter, we will take a look at the idea of web applications with PHP, going from the protocols used to how the web server serves requests, thus setting the foundation for the following chapters.
Chapter 2. Web Applications with PHP
Web applications are a common thing in our lives, and they are usually very user friendly; users do not need to understand how they work behind the scenes. As a developer, though, you need to understand how your application works internally.
In this chapter, you will learn about:
The HTTP protocol
If you check the RFC2068 standard at https://tools.ietf.org/html/rfc2068, you will see that its description is almost endless. Luckily, what you need to know about this protocol, at least for starters, is way shorter.
HTTP stands for HyperText Transfer Protocol. As any other protocol, the goal is to allow two entities or nodes to communicate with each other. In order to achieve this, the messages need to be formatted in a way that they both understand, and the entities must follow some pre-established rules.
A simple example
The following diagram shows a very basic interchange of messages:
A simple GET request
Do not worry if you do not understand all the elements in this diagram; we will describe them shortly. In this representation, there are two entities: sender and receiver. The sender sends a message to the receiver. This message, which starts the communication, is called the request. In this case, the message is a GET request. The receiver receives the message, processes it, and generates a second message: the response. In this case, the response shows a 200 status code, meaning that the request was processed successfully.
HTTP is stateless; that is, it treats each request independently, unrelated to any previous one. This means that with this request and response sequence, the communication is finished. Any new requests will not be aware of this specific interchange of messages.
Parts of the message
An HTTP message contains several parts. We will define only the most important of them.
URL
The URL of the message is the destination of the message. The request will contain the receiver's URL, and the response will contain the sender's.
As you might know, the URL can contain extra parameters, known as a query string. This is used when the sender wants to add extra data. For example, consider this URL: http://myserver.com/greeting?name=Alex. This URL contains one parameter: name with the value Alex. It could not be represented as part of the URL http://myserver.com/greeting, so the sender chose to add it at the end of it. You will see later that this is not the only way that we can add extra information into a message.
The HTTP method
The HTTP method is the verb of the message. It identifies what kind of action the sender wants to perform with this message. The most common ones are GET and POST.
There are other methods, such as PUT, DELETE, or OPTION, but they are less used in web development, although they play a crucial role in REST APIs, which will be explained in Chapter 9, Building REST APIs.
Body
The body part is usually present in response messages even though a request message can contain it too. The body of the message contains the content of the message itself; for example, if the user requested a web page, the body of the response would consist of the HTML code that represents this page.
Soon, we will discuss how the request can also contain a body, which is used to send extra information as part of the request, such as form parameters.
The body can contain text in any format; it can be an HTML text that represents a web page, plain text, the content of an image, JSON, and so on.
Headers
The headers on an HTTP message are the metadata that the receiver needs in order to understand the content of the message. There are a lot of headers, and you will see some of them in this book.
Headers consist of a map of key-value pairs. The following could be the headers of a request:
This request tells the receiver, which is a server, that it will accept text as HTML, which is the common way of representing a web page; and that it has a cookie named Richard.
The status code
The status code is present in responses. It identifies the status of the request with a numeric code so that browsers and other tools know how to react. For example, if we try to access a URL that does not exist, the server should reply with a status code 404. In this way, the browser knows what happened without even looking at the content of the response.
Common status codes are:
A more complex example
The following diagram shows a POST request and its response:
A more complex POST request
In this exchange of messages, we can see the other important method, POST, in action. In this case, the sender tries to send a request in order to update some entity's data. The message contains a cookie ID with the value 84, which may identify the entity to update. It also contains two parameters in the body: name and age. This is the data that the receiver has to update.
Tip
Submitting web forms
Representing the parameters as part of the body is a common way to send information when submitting a form, but not the only one. You can add a query string to the URL, add JSON to the body of the message, and so on.
The response has a status code of 200, meaning that the request was processed successfully. In addition, the response also contains a body, this time formatted as JSON, which represents the new status of the updated entity.
Web servers
So, it is about time that you learn what those famous web servers are. A web server is no more than a piece of software running on a machine and listening to requests from a specific port. Usually, this port is 80, but it can be any other that is available.
How they work
The following diagram represents the flow of request-response on the server side:
Request-response flow on the server side
The job of a web server is to route external requests to the correct application so that they can be processed. Once the application returns a response, the web server will send this response to the client. Let's take a close look at all the steps:
The PHP built-in server
There are powerful web servers that support high loads of traffic, such as Apache or Nginx, which are fairly simple to install and manage. For the purpose of this book, though, we will use something even simpler: a PHP built-in server. The reason to use this is that you will not need extra package installations, configurations, and headaches as it comes with PHP. With just one command, you will have a web server running on your machine.
Note
Production web servers
Note that the PHP built-in web server is good for testing purposes, but it is highly recommended not to use it in production environments. If you have to set up a server that needs to be public and your application is written in PHP, I highly recommend you to choose either of the classics: Apache (http://httpd.apache.org) or Nginx (https://www.nginx.com). Both can run almost on any server, are free and easy to install and configure, and, more importantly, have a huge community that will support you on virtually any problem you might encounter.
Finally, hands on! Let's try to create our very first web page using the built-in server. For this, create an index.php file inside your workspace directory—for example, Documents/workspace/index.php. The content of this file should be:
Now, open your command line, go to your workspace directory, probably by running the cd Documents/workspace command, and run the following command:
The command line will prompt you with some information, the most important one being what is listening, which should be localhost:8000 as specified, and how to stop it, usually by pressing Ctrl + C. Do not close the command line as it will stop the web server too.
Now, let's open a browser and go to http://localhost:8000. You should see a hello world message on a white page. Yay, success! If you are interested, you can check your command line, and you will see log entries of each request you are sending via your browser.
So, how does it really work? Well, if you check again in the previous diagram, the php -S command started a web server—in our case, listening to port 8000 instead of 80. Also, PHP knows that the web application code will be on the same directory that you started the web server: your workspace. There are more specific options, but by default, PHP will try to execute the index.php file in your workspace.
Putting things together
Let's try to include our first project (index.html with its CSS and JS files) as part of the built-in server. To do this, you just need to open the command line and go to the directory in which these files are and start the web server with php -S localhost:8000. If you check localhost:8000 in your browser, you will see our two-link page, as is expected.
Let's now move our new index.php file to the same directory. You do not need to restart your web server; PHP will know about the changes automatically. Go to your browser and refresh the page. You should now see the hello world message instead of the links. What happened here?
If you do not change the default options, PHP will always try to find an index.php file in the directory in which you started the web server. If this is not found, PHP will try to find an index.html file. Previously, we only had the index.html file, so PHP failed to find index.php. Now that it can find its first option, index.php, it will load it.
If we want to see our index.html file from the browser, we can always specify it in the URL like http://localhost:8000/index.html. If the web server notices that you are trying to access a specific file, it will try to load it instead of the default options.
Finally, if we try to access a file that is not on our filesystem, the web server will return a response with status code 404—that is, not found. We can see this code if we open the Developer tools section of our browser and go to the Network section.
Tip
Developer tools are your friends
As a web developer, you will find very few tools more useful than the developer tools of your browser. It changes from browser to browser, but all of the big names, such as Chrome or Firefox, have it. It is very important that you get familiar with how to use it as it allows you to debug your applications from the client side.
I will introduce you to some of these tools during the course of this book.
Summary
In this chapter, you learned what HTTP is and how web applications use it in order to interact with the server. You also now know how web servers work and how to launch a light built-in server with PHP. Finally, you took the first steps toward building your first web application. Congratulations!
In the next chapter, we will take a look at the basics of PHP so that you can start building simple applications.
Chapter 3. Understanding PHP Basics
Learning a new language is not easy. You need to understand not only the syntax of the language, but also its grammatical rules, that is, when and why to use each element of the language. Luckily for you, some languages come from the same root. For example, Spanish and French are Romance languages, as they both evolved from spoken Latin; that means that these two languages share a lot of rules, and if you already know French, learning Spanish becomes much easier.
Programming languages are quite the same. If you already know another programming language, it will be very easy for you to go through this chapter. If this is your first time though, you will need to understand all those grammatical rules from scratch, and so, it might take some more time. But fear not! We are here to help you in this endeavor.
In this chapter, you will learn about the following:
PHP files
From now on, we will work on your index.php file, so you can just start the web server, and go to http://localhost:8080 to see the results.
You might have already noticed that in order to write PHP code, you have to start the file with <?php. There are other options, and you can also finish the file with ?>, but none of them are needed. What is important to know is that you can mix PHP code with other content, like HTML, CSS, or JavaScript, in your PHP file as soon as you enclose the PHP bits with the <?php ?> tags.
If you check the result of the preceding code snippet in your browser, you will see that it prints both messages, hello world and bye world. The reason why this happens is simple: you already know that the PHP code there prints the hello world message. What happens next is that anything outside the PHP tags will be interpreted as is. If there is an HTML code for instance, it would not be printed as is, but will be interpreted by the browser.
You will learn in Chapter 6, Adapting to MVC, why it is usually a bad idea to mix PHP and HTML. For now, assuming that it is bad, let's try to avoid it. For that, you can include one file from another PHP file using any one of these four functions:
Each function has its own usage, so it is not right to say that one is better than the other. Just think carefully what your scenario is, and then decide. For example, let's try to include our index.html file from our index.php file such that we do not mix PHP with HTML, but have the best of both worlds:
We chose require as we know the file is there—and if it is not, we are not interested in continuing the execution. Moreover, as it is some HTML code, we might want to include it multiple times, so we did not choose the require_once option. You can try to require a file that does not exist, and see what the browser says.
PHP does not consider empty lines; you can add as many as you want to make your code easier to read, and it will not have any repercussion on your application. Another element that helps in writing understandable code, and which is ignored by PHP, is comments. Let's see both in action:
The code does the same job as the previous one, but now everyone will easily understand what we are trying to do. We can see two types of comments: single-line comments and multiple-line comments. The first type consists of a single line starting with //, and the second type encloses multiple lines within /* and */. We start each commented line with an asterisk, but that is completely optional.
