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Agile Web Application Development with Yii1.1 and PHP5

Chapter 1. Meet Yii

The past several years have marked a significant 'framework boom', and almost everyone involved in web application development these days is a part of a new generation of 'framework boomers'. Web development frameworks help jumpstart your application by immediately delivering the core foundation and plumbing needed to quickly turn your ideas scribbled on the whiteboard into a functional and production-ready code. With all of the common features expected from web applications today and available framework options that meet these expectations, there is little reason to code your next web application from scratch. A modern, flexible, and extensible framework is almost as essential a tool as the programming language itself to today's web developer. Moreover, when the two are particularly complementary, the results are an extremely powerful toolkit: Java and Spring, Ruby and Rails, C# and .NET, and PHP and Yii.

Yii is the brainchild of its founder Qiang Xue who started the development of this open source framework on January 1st, 2008. Prior to this, Qiang had previously developed and maintained the PRADO framework for many years. The years of experience and user feedback cultivated from the PRADO project solidified the need for a much easier, more extensible and more efficient PHP5-based framework to meet the ever-growing needs of application developers. The initial alpha version of Yii was officially released to meet these needs in October of 2008. Its extremely impressive performance metrics when compared to other PHP-based frameworks immediately drew very positive attention. On December 3rd, 2008, Yii 1.0 was officially released and as of March 14th, 2010, the latest production-ready version is 1.1.2. It has a growing development team and continues to gain popularity among PHP developers everyday. We feel that with just a little help from the information contained in this book, you will soon understand why.

The name Yii (an acronym for Yes, it is, pronounced as Yee or [ji:]) stands for easy, efficient, and extensible. Yii is a high-performance, component-based, web application framework written in PHP 5. Yii makes it easier to create and maintain large-scale web applications. It also makes them more efficient and extensible. Let's take a quick look at each of these characteristics of Yii in turn.

MVC architecture

As mentioned previously, Yii is an MVC framework and it provides an explicit folder structure for each piece of model, view, and controller code. Before we start building our first Yii application, we need to define a few key terms, and look at how Yii implements and enforces this MVC architecture.

The model

Typically in an MVC architecture, the model is responsible for maintaining state. Thus, it should encapsulate the business rules that apply to the data that defines this state. A model in Yii is any instance of the framework class CModel or its child class. A model class typically comprises data attributes that can have separate labels (something user-friendly for the purpose of display), and can be validated against a set of rules defined in the model. The data that makes up the attributes in the model class could come from a row of a database table or from the fields in a user input form.

Yii implements two kinds of models: The form model (CFormModel class) and the active record model (CActiveRecord class). They both extend from the same base class CModel. CFormModel represents a data model that collects inputs in HTML form. It encapsulates all the logic for form field validation and any other business logic that may need to be applied to the form field data. It can then store this data in memory, or with the help of an active record model, store data in a database.

Active Record (AR) is a design pattern used to abstract database access in an object-oriented fashion. Each AR object in Yii is an instance of CActiveRecord or its child class that wraps a single row in a database table or view, encapsulates all the logic and details around database access, and houses much of the business logic that is required to be applied to that data. The data field values for each column in the table row are represented as properties of the AR object. AR is described in more detail a little later.

The view

Typically, the view is responsible for rendering the user interface, based on the data in the model. A view in Yii is a PHP script that contains user interface related elements, often built using HTML, but can also contain PHP statements. Usually any PHP statements within the view are very simple conditional or looping statements, or refer to other Yii UI-related elements such as HTML helper class methods or prebuilt widgets. More sophisticated logic should be separated from the view and placed appropriately in either the model (if dealing directly with the data), or in the controller for a more general business logic.

The controller

The controller is our main director of a routed request and is responsible for taking user input, interacting with the model, and instructing the view to update and display appropriately. A controller in Yii is an instance of CController or its child. When a controller runs, it performs the requested action, which then interacts with needed models and renders an appropriate view. An action, in its simplest form, is a controller class method whose name starts with the word action.

Stitching these together: Yii request routing

In most MVC implementations, a web request typically has the following lifecycle:

The browser sends the request to the server hosting the MVC application.
A controller is invoked to handle the request.
The controller interacts with the model.
The controller invokes the view.
The view renders the data (often as HTML) and returns it to the browser for display.

Yii's MVC implementation is no exception. In a Yii application, incoming requests from the browser are first received by a router. The router analyzes the request to decide where in the application it should be sent for further processing. In most cases, the router identifies a specific action method within a controller class to which the request is passed. This action method will look at the incoming request data, possibly interact with the model, and perform other needed business logic. Eventually, this action class will prepare the response data and send it to the view class. The view will then massage this data to conform to the desired layout and design, and return it for the browser to display.

Blog posting example

To help all of this make more sense, let's look at a fictitious example. Pretend we have used Yii to build ourselves a new blog site, yourblog.com. This site is similar to most typical blog sites out there. The home page displays a list of recently posted blog posts. The names of each of these blog postings are hyperlinks that take the user to the page that displays the full article. The next diagram illustrates how Yii handles an incoming request sent from clicking on one of these hypothetical blog post links.

The figure traces the request made from a user clicking on the following link: http://yourblog.com/post/show/id/99

First, the request is sent to the router. The router parses the request to decide where to send it. The structure of the URL is key to the decision the router will make. By default, Yii recognizes URLs with the following format: http://hostname/index.php?r=ControllerID/ActionID

The r querystring variable refers to the route that is analyzed by the Yii router. It will parse this route to determine the appropriate controller and action method to further handle the request. Now, you may have immediately noticed that the URL mentioned in the previous example does not follow this default format. It is a simple matter to configure the application to recognize the more search engine friendly format: http://hostname/ControllerID/ActionID

We will continue to use this simplified format for the purposes of this example. The ControllerID in the URL refers to the name of the controller. By default this is the first part of the controller class name, up to the word Controller. For example, if your controller class name is TestController, the ControllerID would be Test. Similarly, ActionID refers to the name of the action that is defined by the controller. If the action is a simple method defined within the controller, this will be whatever follows the word Action in the method name. For example, if your action method is named actionCreate() , the ActionID is Create.

Note

If the ActionID is omitted, the controller will take the default action, which is a method in the controller called actionIndex(). If the ControllerID is also omitted, the application will use the default controller. The Yii default controller is called SiteController .

Turning back to the example, the router will analyze the following URL, http://yourblog.com/post/show/id/99, and will take the first part of the URL path, post to be the ControllerID and the second part, show to be the ActionID. This will translate to routing the request to the actionShow() method within the PostController class. The last part of the URL (id/99) is a name/value querystring parameter that will be available to the method during processing. In this example, 99 represents the unique internal id for the selected blog post.

The actionShow() method handles requests for specific blog post entries. In this case, it uses the querystring variable, id to determine which specific post is being requested. It asks the model to retrieve information about blog post entry number 99. The model AR class interacts with the database to retrieve the requested data. After retrieving the data from the model, the controller class further prepares it for display by making it available to the view. The view then renders the needed HTML in a response back to the user's browser.

This MVC architecture allows us to separate the presentation from the model, and the controller from the view. This makes it easy for developers to change aspects of the application without affecting the User Interface (UI) and for UI designers to freely make changes without affecting the model or business logic. This separation also makes it very easy to provide multiple presentations of the same model code. For example, you could use the same model code that drives the HTML layout of yourblog.com to drive a Flash/Flex RIA presentation or a mobile application or web services, or a command-line interface. In the end, following this set conventions and separating the functionality will result in an application that is much easier to extend and maintain.

Yii does a lot more to help you enforce this separation than simply providing some naming conventions and suggestions for where your code should be placed in a folder structure. It helps to take care of all the lower-level glue code needed to stitch all the pieces together. This allows you to reap the benefits of a strict MVC designed application without having to spend all the time coding the details yourself. Let's take a look at some of these lower-level details.

Object-relational mapping and Active Record

For the most part, the web applications we build house their data in a relational database. The blog posting application we used in the previous example holds blog post content in database tables. However, web applications need the data that is held in the persistent database storage mapped to in-memory class properties that define the domain objects. Object-relational mapping (ORM) libraries provide this mapping of database tables to domain object classes.

Much of the code that deals with ORM is about describing how fields in the database correspond to fields in our objects, which is tedious and repetitive to write. Luckily, Yii comes to our rescue to save us from this repetition and tedium by providing the ORM layer in the form of the AR pattern.

Active Record

As was previously mentioned, AR is a design pattern used to abstract database access in an object-oriented fashion. It maps tables to classes, rows to objects and columns to object attributes. In other words, each instance of an active record class represents a single row in a database table. However an AR class is more than just a set of attributes that map to columns in a database table; it also houses the needed business logic behavior to be applied to that data. The end result is a class that defines everything about how it should be written to and read from the database.

By relying on convention and sticking with reasonable defaults, Yii's implementation of AR will save the developer a ton of time normally spent in configuration or in writing tedious and repetitive SQL statements required to create, read, update and delete data. It also allows the developer to access data stored in the database in a much more object-oriented way. To illustrate this, here is some example code that uses AR to operate on a specific blog posting whose internal id, which is also used as the table's Primary Key, is 99. It first retrieves the posting by Primary Key, it then changes the title, and then updates the database to save the changes:

$post=Post::model()->findByPk(99);
$post->title='Some new title';
$post->save();

Active Record completely relieves us of the tedium of having to write any SQL or otherwise deal with the underlying database.

Note

Active Record does even more than this. It integrates seamlessly with many other aspects of the Yii Framework. There are myriad active html helper input form fields that tie directly to their respective AR class attributes. This way, Active Record extracts the input form field values directly into the model. It also supports sophisticated, automated data validation, and if the validation fails, the Yii view classes easily display the validation errors to the end user. We will be revisiting AR and providing many concrete examples throughout this book.

Key benefits

A step-by-step guide to creating a modern, sophisticated web application using an incremental and iterative approach to software development

Build a real-world, user-based, database-driven project task management application using the Yii development framework

Take a test-driven design (TDD) approach to software development utilizing the Yii testing framework

Write less code by using Yii's application generation and scaffolding tools

Enhance your application by adding Web feeds, adapting it to multiple languages, and by utilizing themes to provide beautiful skins and design flexibility

Description

This book is a step by step tutorial in developing a real-world application using the incremental and iterative approach to software development. You learn about agile software development by leaning on the agile nature of the Yii application development framework. You touch on each aspect of the software development lifecycle by building a project task management application from concept through production deployment.After a brief, general introduction to the Yii framework and outlining the software development approach taken throughout the book, the chapters break down in the same way as software development iterations do in real-world projects. After the 1st iteration, you will have a working and tested application with a valid, tested connection to a database.In the 2nd and 3rd iterations, we flesh out our main database entities and domain object model and become familiar with Yii's object-relational-mapping (ORM) layer, Active Record. We also learn how to lean on Yii's auto-generation tools to automatically build our create/read/update/delete (CRUD) functionality against our newly created model. These iterations also focus on how Yii's form validation and submission model works. By the end of the third iteration you will have a working application that allows you to mange projects and issues (tasks) within those projects.The 4th and 5th iterations are dedicated to user management. We learn about the built-in authentication model within Yii to assist in application login and logout functionality. We then dive into the authorization model, first taking advantage of a Yii's simple access control model, then implementing the more sophisticated role-based access control (RBAC) framework that Yii provides.By the end of the 5th iteration, all of the basics of a task management application are in place. The next several iterations are focused on the nice-to-haves. We add user comment functionality, introducing a reusable content portlet architecture approach in the process. We add in an RSS Web feed and demonstrate how easy it is to integrate other third-party tools within a Yii application. We take advantage of Yii's theming structure to help streamline and design the application, and then introduce Yii's internationalization (I18N) features so the application can be adapted to various languages and regions without engineering changes.Finally, we turn our focus to production deployment. We introduce ways to optimize performance and security to prepare the application for a real-world production environment.

What you will learn

Take a "test first" approach to software development using the Yii testing framework

Auto-generate skeleton web applications as well as CRUD scaffolding for the domain object model using the built-in command-line interface

Create user-based applications with Yii s authentication model

Enhance your user-based application to control a user s access to feature functionality

Write an administrative console application to extend the features provided by Yii s powerful command-line tools

Integrate other frameworks and libraries into a Yii application to further extend its feature set

Spend less time managing application configuration by taking advantage of Yii s sensible defaults and conventions.

Learn how easy it is to implement a multi-user application by utilizing Yii s authentication and role-based authorization models

Update your code to properly mange the user s last login time and store it in the database

Achieve pre- and post-action method request processing using controller filters

Tap into the CActiveRecord validation workflow to allow for pre- and post-validation processing of your model data

Greatly increase re-use, consistency, and ease of maintenance of the application by developing small content blocks called portlets

Make your application accessible to the world with internationalization (l18N) features and enhance the looks of your application using the Yii theming model

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Paperback book shipped to your preferred address

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Agile Web Application Development with Yii1.1 and PHP5

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Amazon verified reviews

BoazR Jan 08, 2012

All in all I'd highly recommend this book to Yii newcomers who'd like and prefer a trusty tutorial to follow and have the time to read it:* Its topics range is very good.* TDD approach is a big big plus.* It builds nicely in each chapter on preceding chapters.* It covers not only topics that are needed to implement the example web application built throughout the book but rather more important stuff to be aware of: caching, testing (as mentioned above), logging and probably more that I don't remember at the moment.* Its depth of coverage is good - not too deep, not too shallow.* It has some typos and other issues but all in all - I'd highly recommend it to newcomers for the above reasons.

Amazon Verified review

Chad Huntley Dec 14, 2010

About a year ago I tried learning Yii just through online materials. I've never worked with a framework before, and struggled understanding it. I eventually gave up.As soon as I learned there was a book available I decided to give that a shot. I now have a very strong understanding of Yii and have already built a fully-functioning website from it. The book does a great job explaining key concepts of the framework, which makes learning the rest on your own a breeze.One problem with the book is the editing, there are a decent amount of typos and errors. I recommend checking out the official "Identified Issues" page on the official Yii forums, grabbing a pen, and fixing the errors yourself. Another problem is that sometimes the author adds new concepts into code examples, but does not properly explain them. But again, you can take it to yourself to browse through the Yii site or start asking questions on their forums.Overall this a great book!

Harry Kendall Aug 20, 2014

A very clear and methodical progression of the main concepts of yii, one of the best Yii books i have found for "understanding" yii, the only downside is maybe the heavy focus on testing can be a distraction from the main ideas being taught, but i have read this book all the way through, and still use it regularly to remind me of forgotten concepts...

Petr Gromov May 10, 2012

The content itself is very accurate and clear, it's extremelly easy to learn Yii using this book.However there are some typographical mistakes, that are made during layout creation.

Tiffany Puett Dec 18, 2012

It should be noted that there is a new edition of this book out now. It was released under a slightly different title and that may be the reason it is not obvious from this section. Anyone considering purchasing this book should strongly consider the updated edition: Web Application Development with Yii and PHP Also, the author has posted an overview of this new edition, which you may also find useful:[...]

Agile Web Application Development with Yii1.1 and PHP5: For PHP developers who know object-oriented programming, this book is the fast track to learning the Yii framework. It takes a step-by-step approach to building a complete real-world application ‚Äì teaching by practice rather than theory.

What do you get with Print?

Agile Web Application Development with Yii1.1 and PHP5

Chapter 1. Meet Yii

Yii is easy

Yii is efficient

Yii is extensible

MVC architecture

The model

The view

The controller

Stitching these together: Yii request routing

Blog posting example

Note

Object-relational mapping and Active Record

Active Record

Note

The view and controller

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Agile Web Application Development with Yii1.1 and PHP5: For PHP developers who know object-oriented programming, this book is the fast track to learning the Yii framework. It takes a step-by-step approach to building a complete real-world application ‚Äì teaching by practice rather than theory.

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