Yii2初学者入门指南

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"yii2初学者，这是一本适合初学者的关于Yii2框架的入门书籍，作者Bill Keck。" Yii2 是一个基于组件、高性能的 PHP 框架，适用于开发 Web 2.0 应用程序。作为初学者，了解 Yii2 可以帮助你快速构建高效且易于维护的 Web 应用。这本书 "Yii2 For Beginners" 提供了一个逐步学习的指南，旨在帮助初学者掌握 Yii2 的核心概念。 Yii2 的特点包括： 1. **MVC（模型-视图-控制器）架构模式**：Yii2 遵循 MVC 设计模式，分离业务逻辑、数据展示和用户交互，使得代码组织清晰，易于理解和维护。 2. **自动化工作流**：Yii2 提供了代码生成工具（Gii），可以自动生成模型、控制器、表单等代码，大大提高了开发效率。 3. **强大的缓存支持**：Yii2 支持多种缓存策略，包括页面缓存、片段缓存、数据缓存等，能有效提升应用性能。 4. **安全特性**：内置了防止 SQL 注入、XSS 攻击的安全组件，以及认证和授权机制，确保应用安全性。 5. **数据库支持**：Yii2 支持多种数据库，如 MySQL、PostgreSQL、SQLite 等，并提供了 ActiveRecord ORM（对象关系映射），简化数据库操作。 6. **RESTful API 开发**：Yii2 提供了构建 RESTful API 的强大工具，适合移动应用和前后端分离的开发模式。 7. **单元测试与持续集成**：Yii2 支持 PHPUnit 进行单元测试，方便进行自动化测试和持续集成。在学习这本书之前，建议先熟悉 PHP 基础和 Web 开发的基本概念，然后阅读 Yii2 的官方文档，了解基本框架结构和配置。接下来，通过 "Yii2 For Beginners" 逐步学习框架的使用方法和最佳实践。书中的每个章节可能涵盖以下内容： - 安装和配置 Yii2 框架 - 创建第一个 Yii2 应用 - MVC 结构的深入理解 - 数据库交互和 ActiveRecord - 视图和模板渲染 - 表单处理和验证 - 用户认证和授权 - 错误处理和日志记录 - 缓存和性能优化 - RESTful API 的创建 - 测试和调试技巧通过本书的学习，你将能够独立开发基于 Yii2 的 Web 应用，并具备进一步研究更高级特性和扩展能力的基础。同时，作者 Bill Keck 鼓励读者积极参与社区，分享知识，这不仅是个人成长的过程，也是对社区的贡献。

Chapter One: Introduction 3

Upsides

Here are some of the obvious benefits:

• Uses standard ways of doing things, so reduces or eliminates spaghetti code.

• Reduces time spent on plumbing tasks such as form validation and security.

• Makes it easier to work as a team by enforcing standards.

• Makes it easier to maintain code by utilizing a common architecture and methods.

• You get the benefit of an active community of developers who maintain the framework and

support common tasks and new features.

Downsides

There are a couple of downsides to using a framework that should be pointed out. First, all the code

that comprises the framework creates server overhead and this can be a real problem. Luckily there

are caching options available which will reduce the effects of this, and for enterprise applications,

you can use raw sql to minimize query time. So don’t let the server overhead stop you from using a

framework.

The other thing is that obviously when you are working with the framework, you are working with

a vast amount of code that you didn’t write and it takes time to figure out how it works. Some of

the framework code can be quite cryptic depending on your level of skill and experience, so don’t

expect to instantly understand everything. It’s not going to happen.

Of course you already knew that there was a learning curve, which is why you are reading this

book. And while it takes time to learn someone else’s code, which can be a pain, it would be far

more painful to have to write a custom framework from scratch. All things considered, using a

framework for enterprise development is a wise choice.

Ok, so the easy part is to figure out that utilizing a framework will help you develop a more organized

and robust project, but now comes the hard part. You have decide which framework to use.

Why I chose Yii 2

I can’t tell you which is the best framework for you, that is something for you and you alone to

decide, but I can share a little of the journey that led me to Yii 2. This decision wasn’t driven by the

need to find the easiest way to learn PHP, that is for sure.

At my company back in 2012, I was part of team of developers who looked at various frameworks

and had to decide which one to use. I never dreamed at the time that I would end up writing a book

about one of them.

Chapter One: Introduction 4

Anyway, we collectively researched everything we could find on the major PHP frameworks. I

personally read all of the documentation and we had long engineering discussions about what

we thought would work. You can’t imagine my frustration with the fact that I read all this

documentation and walked away from it feeling less knowledgeable than before I started reading it.

Our team of programmers did have a preference however. They felt that Yii 1.1.14 was the best

choice. This was the version of Yii that was available at the time we were deciding this. So the team

adopted that framework and never looked back. They loved it.

I, on the other hand, remained frustrated. Since I was only a novice programmer, I really struggled

to learn it. I didn’t find it very intuitive. Especially after comparing it to other frameworks, where

they were trying so hard to make everything integrate beautifully, the architecture of Yii just seemed

ugly.

I got so frustrated at one point, that I started looking for another option.

Other Options

I would find some beautifully written documentation for a new framework and run it past the team.

I always got the same response. The team was happy with Yii.

They told me it might be difficult to learn, but it was easy to use, once you knew how it worked.

Because of that, I committed myself to learning it. It was slow going and a rough ride. I wasn’t

getting it. I was working through chapter 10 in a book on Yii 1.1.14, thinking I would never really

be able to build an application on my own in less than a hundred years. Too many roads seemed to

go nowhere.

Then a miracle happened.

Yii 2 Arrives

I found out about the Yii 2 alpha. I was curious to see what the differences were in Yii 2, which had

been 3 years in the making at that point. So I jumped in and to my utter and complete surprise, I

instantly connected with it. I understood the structures. I could write code that actually worked!

What a great feeling that was.

I have personally found Yii 2 to be the most intuitive and elegant of all the PHP frameworks that

I have studied. I have so much enthusiasm for it that I want to share it with every programmer I

know, and even those I don’t know, so it has motivated me to write this book.

With Yii 2, even as a beginner, I was able to stand up a working website that has a data-driven user

model, with both a frontend and a backend. Right out of the box, I get a working user model, with

forgot password functionality, which is also integrated with Bootstrap for mobile-responsive design,

without having to do any programming whatsoever. How cool is that?

Although I was a beginning programmer when I was studying the PHP frameworks, I did have

experience working with databases and this is one area in my opinion where Yii 2 really shines.

Chapter One: Introduction 5

Gii

Yii 2 has a code generation tool called Gii. I pronounce that with a soft “g,” but I have no idea if that

is the right way to say it or not.

Anyway, Gii analyzes your database tables and automatically builds PHP models from them. Not

only that, but it analyzes the relationships between tables and automatically generates the relational

code into the models. For example, if you had a data structure with 30 tables, and half of them had

a user_id column that was meant to reference id of the user table, Gii would build the appropriate

relationships for you, each time you built a model. Not only is this a time-saver, but this also gives you

very consistent code because it is always done the same way and it helps you adopt this discipline.

It’s worth mentioning that other frameworks work exactly the opposite way. With them, you build

the model first, then do a migration to the database to create the table and corresponding columns.

So the big difference is that you are building your data structure piecemeal as you go along, whereas

in Yii 2 you have the option of having a more complete data structure to begin with.

Both approaches work, however they represent drastically different workflows. In my opinion, the

migration/piecemeal approach to data structure only really works for a single developer or a very

small team working on a small project. The reason why I say this is that although democracy is

probably the best system politically, imagine a world where each developer makes up their own

data structure and implements it. How consistent would that be? What if the right hand didn’t

know what the left hand was doing? In larger teams, this is a recipe for chaos. This is why enterprise

development teams usually have a database administrator, also known as the DB, and only they can

create or delete data structure.

DB-First Approach

Since Yii 2 allows you to essentially import the models from the data structure, you can start your

project by really thinking through your data structure. Overall I like to avoid talking about too much

theory because the time is better spent working through hands-on examples, but I think it’s worth

taking a moment to think about what a well thought-out data structure really means.

Whether you are a single developer or part of an enterprise level team, you are essentially being

given the same task, the same overall mission. You have to serve data from a database into a browser-

friendly format, typically using PHP, HTML, and Javascript. We use a PHP framework to make this

task easier, and by saying that, we are admitting upfront that it’s not an easy task. Why is that?

The database is a very reliable and consistent piece of software, which allows us to create a relational

data structure.

MySql

Throughout this book we use Mysql as the database, which, in addition to being free, is capable of

powering enterprise data for web applications.

Chapter One: Introduction 6

Because of the structure of the database, with its indexes and primary keys, a database can serve

data very efficiently. In the simplest terms, this means it is very fast. It’s also very deep. It can hold

millions of records, which can be retrieved, if structured properly, in milliseconds.

Another key aspect of the database is that it allows us to structure the data in such a way as to

connect things like the user’s address and their username as if they were one record, but hold them

in separate tables as separate records. The more you can break down the data structure into discrete

components like that, the more powerful it is. This is called normalization of data.

The problem is that the more refined the database is, the more effectively normalized it is, the more

complex it is to deal with in PHP. You end up having to connect a lot of PHP models together to

represent the data correctly.

Now this might be getting too heavy on theory for a beginning book, so we won’t take this much

further for now, but the point is to understand the nature of the problem that the framework helps to

solve. The easier it is for you to connect the models via the framework, the more power you derive

from your database.

Improved Workflow

In my opinion, Yii 2 stands alone in how it helps you connect the models to the database, leading to

improved workflow, efficiency, and overall design capabilities. It frees you to build a detail-rich data

structure that will ultimately result in the end user being more engaged. I believe that Yii 2 does this

more efficiently and deeply than any of the other PHP frameworks, that is why I’m so committed

to it and so interested in sharing it.

Minimum PHP Skills

Learning a Php framework is simple as long as you are a skilled PHP programmer. Quite often

PHP is a second or third language for a programmer who is already proficient in an object oriented

language like C or Java, so learning PHP is just a matter of adjusting syntax and they pick it up

quickly. That’s great for ninjas, but what happens if you are just learning your first programming

language?

As someone who learned PHP as a first programming language, I can tell you from direct experience

that it’s difficult to move from beginner to advanced because there is not a lot of support for the

middle ground. That fact is one of the motivations for me to write this book.

Anyway, if you search online, you either find incredibly complex examples involving multiple

interfaces with nested objects or examples that are so rudimentary that, while they are easy to

understand, they do nothing to advance your abilities.

To work your way through this book, you will need a decent understanding of object-oriented PHP.

You can get this from a variety of sources online. I got my first taste of PHP from thenewboston.org,

Chapter One: Introduction 7

which has 200 videos on PHP. Great for an introduction, but not much more. I followed that up

with a quick read of Richard Reese’s book on Java, which helped me understand object-oriented

programming better, since everything in Java involves a class. Also, when I looked at PHP again, it

seemed simpler. I also went through the basics at:

W3 Schools

W3schools.com is a great learning resource. You can play with the code online at that site.

And then of course there is Php.net itself which is where we find all the docs for the language and

sometimes very complicated examples. I learned a lot there and got lost a lot too, that’s the way it

goes. Try it, you’ll see what I mean.

At any rate, to be able to work with Yii 2, you should understand the basics about objects, arrays,

and control structures like foreach loops. You should know the components of a class, properties and

methods, etc. Take a look at:

OOP for Beginners

You should be able to get through that tutorial very easily. If not, go back and study it before trying

to tackle Yii 2. Also, Yii 2 uses PHP 5.4 and above, which supports new array syntax and namespaces,

both of which will be utilized extensively.

If you are light on programming experience, but full of enthusiasm, you should do well, as long as

you are willing to do the work and are patient. At any point, if you don’t understand something,

you can stop and take the time to research it on Google or stackoverflow or PHP.net. PHP is a well-

documented and well-supported language, used by countless programmers who will try to help you.

Also, I took a lot of care to label the sub-sections of this book, so you can easily find what you

are looking for, if you need to refer back to it. Many times you will want to return to a section to

reference something and I’ve done my best to make that as intuitive as possible.

Tools You Will Need

There are a number of tools that I recommend that you use for development in Yii 2, all which,

like the framework itself, are free. These are recommendations only, not necessary to follow exactly,

but my instructions will assume you are using them. So if you are advanced enough, you can use

whatever you wish, no big deal. As long as you have working development environment, you are

fine. If not, try to use these exact tools, it will be easier for you in the long run.

Sometimes the most difficult part of a project is setting up the development environment. Because I

use it personally, we will be using xampp up on a windows machine. Xampp includes PHP, Mysql,

Apache, and PhpMyadmin, so it’s perfect to create a development environment for project. It’s also

free.

Download Xampp

Install Video for Xampp and PhpMyadmin

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