Doctrine: How to save a PHP array to a column

Introduction

Doctrine is a powerful object-relational mapper (ORM) for PHP that provides a flexible way to interact with databases. One of the challenges developers may come across when using Doctrine is storing a PHP array in a single database column. This guide will walk you through different methods of persisting a PHP array in a column using Doctrine, starting from basic to more advanced techniques, complete with code examples.

Understanding Doctrine’s Array Type

Before we begin, it is important to understand that Doctrine comes with a variety of field types, one of which is the ‘array’ type. This allows you to easily store and retrieve PHP arrays in a serialized form.

/**
 * @Entity
 * @Table(name="example")
 */
 class Example
 {
     /**
      * @var array
      *
      * @ORM\Column(name="my_array", type="array")
      */
     private $myArray;

     // ...
 }

Basic Usage: Inserting a PHP Array

First, let’s see how you can insert a new record with a PHP array into the database. In this example, we’ll create a simple entity and set the array property before persisting it.

$example = new Example();
$example->setMyArray(['apple', 'banana', 'cherry']);

$entityManager->persist($example);
$entityManager->flush();

When you call the flush() method, Doctrine serializes the array into a string representation and stores it in the specified column.

Retrieving and Working with Stored Arrays

Accessing a stored array is as simple as retrieving the entity and accessing the array property:

$example = $entityManager->find('Example', $id);
$fruits = $example->getMyArray();

// Output the array
print_r($fruits);

This will output the unserialized PHP array, allowing you to work with it within your application.

Advanced Usage: Custom Array Handling

While the built-in array type is convenient, you may need more control over how arrays are stored and retrieved, perhaps to use a different serialization mechanism like JSON.

/**
 * @ORM\Column(type="json")
 */
 private $myArray;

With this approach, when dealing with JSON data, your array will be encoded and decoded automatically by Doctrine without manually serializing or unserializing, ensuring that data remains easily readable and handlable.

Handling Complex Arrays with Custom Types

If your arrays contain complex data types, implementing your own Doctrine type might be a valuable approach. Creating a custom type allows you to tailor the serialization and deserialization process to your needs.

Here’s a condensed version of what creating a custom Doctrine type might look like:

use Doctrine\DBAL\Platforms\AbstractPlatform;
use Doctrine\DBAL\Types\Type;

class CustomArrayType extends Type
{
    public function getSqlDeclaration(array $fieldDeclaration, AbstractPlatform $platform)
    {
        // SQL declaration for the Column
    }

    public function convertToPHPValue($value, AbstractPlatform $platform)
    {
        return unserialize($value);
    }

    public function convertToDatabaseValue($value, AbstractPlatform $platform)
    {
        return serialize($value);
    }

    public function getName()
    {
        return 'custom_array';
    }
}

// Registering the custom type
Type::addType('custom_array', 'My\App\DBAL\Types\CustomArrayType');

// Using the custom type in an entity column
/**
 * @ORM\Column(type="custom_array")
 */
 private $myComplexArray;

By registering a custom type, you have complete control over serialization allowing for bespoke solutions best suited to your application’s needs.

Conclusion

In conclusion, Doctrine’s native array type offers a quick and simple way to save PHP arrays to database columns. For more nuanced needs, such as custom serialization or working with JSON, additional features or custom types can be utilized. Armed with these techniques, you’re now equipped to effectively manage array storage in a Doctrine-based application.