PHP设计模式 PHP 实体-属性-值 (EAV)模式

实体-属性-值 (EAV) 模式以使用 PHP 实现 EAV 模型。

目的

Entity-attribute-value (EAV) 模型是一种描述实体的数据模型，其中可用于描述它们的属性（属性、参数）的数量可能很大，但实际应用于给定实体的数量是比较适中。

UML 图

代码

Entity.php

<?php
declare(strict_types=1);
namespace DesignPatterns\More\EAV;
use SplObjectStorage;
class Entity implements \Stringable
{
    /**
     * @var SplObjectStorage<Value,Value>
     */
    private $values;
    /**
     * @param Value[] $values
     */
    public function __construct(private string $name, $values)
    {
        $this->values = new SplObjectStorage();
        foreach ($values as $value) {
            $this->values->attach($value);
        }
    }
    public function __toString(): string
    {
        $text = [$this->name];
        foreach ($this->values as $value) {
            $text[] = (string) $value;
        }
        return join(', ', $text);
    }
}

Attribute.php

<?php
declare(strict_types=1);
namespace DesignPatterns\More\EAV;
use SplObjectStorage;
class Attribute implements \Stringable
{
    private SplObjectStorage $values;
    public function __construct(private string $name)
    {
        $this->values = new SplObjectStorage();
    }
    public function addValue(Value $value)
    {
        $this->values->attach($value);
    }
    public function getValues(): SplObjectStorage
    {
        return $this->values;
    }
    public function __toString(): string
    {
        return $this->name;
    }
}

Value.php

<?php
declare(strict_types=1);
namespace DesignPatterns\More\EAV;
class Value implements \Stringable
{
    public function __construct(private Attribute $attribute, private string $name)
    {
        $attribute->addValue($this);
    }
    public function __toString(): string
    {
        return sprintf('%s: %s', (string) $this->attribute, $this->name);
    }
}

测试

Tests/EAVTest.php

<?php
declare(strict_types=1);
namespace DesignPatterns\More\EAV\Tests;
use DesignPatterns\More\EAV\Attribute;
use DesignPatterns\More\EAV\Entity;
use DesignPatterns\More\EAV\Value;
use PHPUnit\Framework\TestCase;
class EAVTest extends TestCase
{
    public function testCanAddAttributeToEntity()
    {
        $colorAttribute = new Attribute('color');
        $colorSilver = new Value($colorAttribute, 'silver');
        $colorBlack = new Value($colorAttribute, 'black');
        $memoryAttribute = new Attribute('memory');
        $memory8Gb = new Value($memoryAttribute, '8GB');
        $entity = new Entity('MacBook Pro', [$colorSilver, $colorBlack, $memory8Gb]);
        $this->assertEquals('MacBook Pro, color: silver, color: black, memory: 8GB', (string) $entity);
    }
}