Entire attribute value mode (EAV mode) code examples of PHP design mode (35)

The Entity--attribute--value EAV mode can facilitate PHP's implementation of the EAV model.

purpose

Entity-attribute-value EAV is a data model that describes the attributes (attributes, parameters) of entities. It can be used to describe their potential huge, but in fact, the number of entities that will be applied to a given entity is relative less.

In mathematics, this pattern is called a sparse matrix.

EAV is also known as the object's attribute value model, vertical database model and open architecture.

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Code

• Entity.php

<?php

namespace DesignPatterns\More\EAV;

class Entity
{
    /**
     * @var \SplObjectStorage
     */
    private $values;

    /**
     * @var string
     */
    private $name;

    /**
     * @param string $name
     * @param Value[] $values
     */
    public function __construct(string $name, $values)
    {
        $this->values = new \SplObjectStorage();
        $this->name = $name;

        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

Value.php
<?php

namespace DesignPatterns\More\EAV;

class Attribute
{
    /**
     * @var \SplObjectStorage
     */
    private $values;

    /**
     * @var string
     */
    private $name;

    public function __construct(string $name)
    {
        $this->values = new \SplObjectStorage();
        $this->name = $name;
    }

    public function addValue(Value $value)
    {
        $this->values->attach($value);
    }

    /**
     * @return \SplObjectStorage
     */
    public function getValues(): \SplObjectStorage
    {
        return $this->values;
    }

    public function __toString(): string
    {
        return $this->name;
    }
}

• Value.php

<?php

namespace DesignPatterns\More\EAV;

class Value
{
    /**
     * @var Attribute
     */
    private $attribute;

    /**
     * @var string
     */
    private $name;

    public function __construct(Attribute $attribute, string $name)
    {
        $this->name = $name;
        $this->attribute = $attribute;

        $attribute->addValue($this);
    }

    public function __toString(): string
    {
        return sprintf('%s: %s', $this->attribute, $this->name);
    }
}

test

• Tests/EAVTest.php

<?php

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);
    }
}

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