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PHP Doctrine指南：对象持久化实战与技术解密

Persistence

Doctrine

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"《PHP Persistence: Concepts, Techniques, and Practical Solutions with Doctrine》是一本由Michael Romer撰写的面向经验丰富的PHP程序员和Web开发者的专业书籍。该书旨在帮助读者在面向对象编程的世界中轻松管理关系型数据库，通过 Doctrine 持久化框架实现高效开发。Doctrine 是PHP程序员和Web开发者广泛使用的领先持久化解决方案。书中内容深入浅出，从基础概念讲起，包括实体（Entities）的定义、实体之间的引用关系，以及如何有效地使用对象关系映射（ORM）技术。读者将学会如何： 1. 定义实体及其之间的关联。 2. 管理实体数据，包括CRUD操作。 3. 掌握 Doctrine 查询语言，编写高效查询。 4. 利用合适的命令行工具进行PHP持久化操作。 5. 应用缓存技术以提高性能。 6. 探索高级主题，如适应不断发展的技术。作者Michael Romer以其丰富的实践经验，带领读者逐步了解并掌握Doctrine 2的使用方法，适合已经有PHP基础并有一定数据库经验的开发者阅读。本书不仅提供了理论知识，还提供了实际操作指导，确保读者能够在项目中快速上手和实现高效开发。本书的出版信息包括ISBN-13（平装版：978-1-4842-2558-5，电子版：978-1-4842-2559-2），DOI（10.1007/978-1-4842-2559-2），以及版权和商标注意事项。通过阅读这本书，开发者可以减少编码工作量，提升项目的质量和效率，是PHP开发者数据库驱动应用开发的实用指南。"

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Chapter 2 ■ IntroduCtIon

Our demo domain model is designed to use as many different association types as

possible, so that we can see most of the features of Doctrine 2 in action in the scope of

the demo application. In a real application, the domain model would probably look a bit

different. As you can see, not every association between entities is bidirectional. And as we

will see later in this book, this is an essential feature of an object-relational mapping (ORM)

system such as Doctrine 2 living in the object-oriented world. In relational databases, there

are no unidirectional associations; they are always bidirectional by design.

M. Romer, PHP Persistence, DOI 10.1007/978-1-4842-2559-2_3

CHAPTER 3

A Self-Made ORM

I believe that showing is always better than telling. Therefore, instead of simply listing the

pros and cons of Doctrine 2, I like to demonstrate what it looks like not having it in your

PHP toolkit when dealing with PHP objects and relational databases.

Jump straight into Doctrine 2? This section illustrates why Doctrine 2 is such a

big help for the application developer. Step by step, we will implement, on our own, certain

ORM features that are already included in Doctrine 2. This chapter is not needed to learn

Doctrine 2, but it helps in understanding why one should learn it.

Loading an Entity

A domain model is a good thing. As long as the application developer acts in the familiar

object-oriented world, there are no obstacles to designing and implementing a domain

model. Design and implementation become harder, though, if it becomes necessary to

persist objects of the domain model in relational databases or to load and reconstruct

previously stored objects. There is, for instance, the fact that objects are more than just

dumb data structures. With their methods, they have behavior as well. Let’s consider the

User entity definition of the Talking demo application:

1 <?php

2 namespace Entity;

4 class User

5 {

6 private $id;

7 private $firstName;

8 private $lastName;

9 private $gender;

10 private $namePrefix;

12 const GENDER_MALE = 0;

13 const GENDER_FEMALE = 1;

CHAPTER 3 ■ A SELF-MADE ORM

15 const GENDER_MALE_DISPLAY_VALUE = "Mr.";

16 const GENDER_FEMALE_DISPLAY_VALUE = "Ms.";

18 public function assembleDisplayName()

19 {

20 $displayName = '';

22 if ($this->gender == self::GENDER_MALE) {

23 $displayName .= self::GENDER_MALE_DISPLAY_VALUE;

24 } else if ($this->gender == self::GENDER_FEMALE) {

25 $displayName .= self::GENDER_FEMALE_DISPLAY_VALUE;

26 }

28 if ($this->namePrefix) {

29 $displayName .= ' ' . $this->namePrefix;

30 }

32 $displayName .= ' ' . $this->firstName . ' ' . $this->lastName;

34 return $displayName;

34 }

37 public function setFirstName($firstName)

38 {

39 $this->firstName = $firstName;

40 }

42 public function getFirstName()

43 {

44 return $this->firstName;

45 }

47 public function setGender($gender)

48 {

49 $this->gender = $gender;

50 }

52 public function getGender()

53 {

54 return $this->gender;

55 }

57 public function setId($id)

58 {

59 $this->id = $id;

60 }

62 public function getId()

CHAPTER 3 ■ A SELF-MADE ORM

63 {

64 return $this->id;

65 }

67 public function setLastName($lastName)

68 {

69 $this->lastName = $lastName;

70 }

72 public function getLastName()

73 {

74 return $this->lastName;

75 }

77 public function setNamePrefix($namePrefix)

78 {

79 $this->namePrefix = $namePrefix;

80 }

82 public function getNamePrefix()

83 {

84 return $this->namePrefix;

85 }

86 }

Listing 1.1

Interesting here is the method assembleDisplayName(). It creates the “display name” for

a user based on a user’s data. The display name is used to print a post’s author.

1 <?php

2 include('../entity/User.php');

4 $user = new Entity\User();

5 $user->setFirstName('Max');

6 $user->setLastName('Mustermann');

7 $user->setGender(0);

8 $user->setNamePrefix('Prof. Dr');

10 echo $user->assembleDisplayName();

Listing 1.2

The code in Listing 1.2 results in:

1 Mr. Prof. Dr. Max Mustermann

CHAPTER 3 ■ A SELF-MADE ORM

The method assembleDisplayName() therefore defines a specific behavior of a User

object.

If a user’s master data is retrieved from the database, it must be transformed in a way

that allows the behavior described above to be attached to it. In other words, the user’s

master data, retrieved from the database, must be transformed into a User object. Within

the application, we always want to deal with objects of our domain so that we can easily

create a User’s display name by simply calling its assembleDisplayName() method. Let’s

build that into our ORM tool.

First, we set up the database structure:

1 CREATE TABLE users(

2 id int(10) NOT NULL auto_increment,

3 first_name varchar(50) NOT NULL,

4 last_name varchar(50) NOT NULL,

5 gender ENUM('0','1') NOT NULL,

6 name_prefix varchar(50) NOT NULL,

7 PRIMARY KEY (id)

8 );

Then, let’s add dummy data for “Max Mustermann” (the German “John Doe,”

by the way):

1 INSERT INTO users (first_name, last_name, gender, name_prefix)

2 VALUES('Max', 'Mustermann', '0', 'Prof. Dr.');

Now, if we want to reconstruct the User object from the database, we can do it like this:

1 <?php

2 include('../entity/User.php');

4 $db = new \PDO('mysql:host=localhost;dbname=app', 'root', '');

5 $userData = $db->query('SELECT * FROM users WHERE id = 1')->fetch();

7 $user = new Entity\User();

8 $user->setId($userData['id']);

9 $user->setFirstName($userData['first_name']);

10 $user->setLastName($userData['last_name']);

11 $user->setGender($userData['gender']);

12 $user->setNamePrefix($userData['name_prefix']);

14 echo $user->assembleDisplayName();

Database credentials in live systems In a live system, you use strong keywords

and don’t work with user “root,” right? The code shown above is just an example …

剩余117页未读，继续阅读

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PHP Doctrine指南：对象持久化实战与技术解密

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