best way to get from an array to a DTO / Object class

[tacman]

Many APIs return an array of hashed arrays. I keep thinking there must be a good way to work with those responses.

I often use PropertyAccessor to go through each key and see if I can set the value, but perhaps there's a Symfony way, given recent tools like MapQueryParameter.

I think I want to create a POP object

class Instance {
    public $guid;
    public $storageZoneName,
    public string $path;
    etc.
}

and then when I get my results back, somehow "cast" the results to the object.

0 => array:15 [▼
      "Guid" => "343dc1cd-b3ce-454a-b7b9-53c4926c6bdd"
      "StorageZoneName" => "museado"
      "Path" => "/museado/photos finales/"
      "ObjectName" => "1.jpeg"
      "Length" => 208838
      "LastChanged" => "2024-06-05T12:59:28.67"
    ]

My semi-solution:

        $propertyAccessor = PropertyAccess::createPropertyAccessor();
        foreach ($result as $var=>$val) {

            try {
                $propertyAccessor->setValue($this, $var, $val);
            } catch (NoSuchPropertyException $exception) {
                //
            } catch (\InvalidArgumentException $exception) {
                // it might be a date string
                try {
                    $date = new \DateTimeImmutable($val);
                    $propertyAccessor->setValue($this, $var, $date);

                } catch (\Exception $e) {
                    dump($var, $val, $e); assert(false);
                }

            }

Thanks.

[berkut1]

Did you check https://symfony.com/doc/current/components/serializer.html ?

In the past, I found it difficult to understand the Symfony component, and it was much faster to write my own version.

My "dirty" solution that I created 2 years ago to create a DataView from the DB. Please don't judge too harshly; I wasn't too concerned about following best practices.

Caution, my handwritten solution

Classes:

final class CustomFetcher
{
    /**
     * @return CustomObjectInterface[]
     * @throws Exception
     */
    public function fetchCustomObjectArray(Result $statement, CustomObjectInterface $customObjectClass): array
    {
        $arr = [];
        foreach ($statement->fetchAllAssociative() as $row) {
            $arr[] = $customObjectClass::fromArray($row);
        }
        return $arr;
    }

    /**
     * @throws Exception
     */
    public function fetchCustomObject(Result $statement, CustomObjectInterface $customObjectClass): ?CustomObjectInterface
    {
        foreach ($statement->fetchAllAssociative() as $row) {
            /** @var CustomObjectInterface $result */
            $result = $customObjectClass::fromArray($row);
            return $result;
        }
        return null;
    }
}

interface CustomObjectInterface
{
    public static function fromArray(array $data = []): object;
}

trait FromArrayTrait 
{
    public static function fromArray(array $data = []): self
    {
        foreach (get_object_vars($obj = new self) as $property => $default) {
            if ($default === null) {
                throw new \UnexpectedValueException('Oops in your class is a null property - ' . self::class);
            }
            $type = gettype($default);
            $var = $data[$property] ?? $default;
            if (!is_object($default) || is_object($var)) {
                settype($var, $type);
                $obj->$property = $var;
                continue;
            }

            $class = $default::class;
            if (enum_exists($class)) {
                /** @var \UnitEnum $class https://www.php.net/manual/en/class.unitenum.php */
                $obj->$property = $class::from($var);
                continue;
            }

            //TODO: add check if exist a special static method for that, like ::create ?
            $obj->$property = new $class($var);
        }
        return $obj;
    }
}

How to use:

final class SomeDataView implements CustomObjectInterface
{
    use FromArrayTrait;

    public Id $id;
    public string $name = '';
    public string $someString = '';
    public ItemEnum $itemEnum = ItemEnum::ITEM;

    public function __construct() //because I have made that null is not acceptable we have to init all values :)
    {
        $this->id = new Id((new NilUlid())->toRfc4122());
    }
}

Inject CustomFetcher

$result = $this->customFetcher->fetchCustomObject($qb->executeQuery(), new SomeDataView);

[Trismegiste]

You can use the Serializer component, specifically the PropertyNormalizer normalizer :

<?php 

require_once __DIR__ . '/vendor/autoload.php';

use Symfony\Component\Serializer\Normalizer\PropertyNormalizer;

class Instance {
    public $guid;
    public $storageZoneName;
    public string $path;
    private int $answer = 42;
}

$instance = new Instance();
$instance->path = 'yolo';

$reflectionNormalizer = new PropertyNormalizer();

// object to array :
$dump = $reflectionNormalizer->normalize($instance);
var_dump($dump);

// array to object : 
$newObject = $reflectionNormalizer->denormalize($dump, Instance::class);
var_dump($newObject);

It should dump :

root@flo-HP-All-in-One-24-f0xx:/app# php essai.php 
array(4) {
  ["guid"]=>
  NULL
  ["storageZoneName"]=>
  NULL
  ["path"]=>
  string(4) "yolo"
  ["answer"]=>
  int(42)
}
object(Instance)#12 (4) {
  ["guid"]=>
  NULL
  ["storageZoneName"]=>
  NULL
  ["path"]=>
  string(4) "yolo"
  ["answer":"Instance":private]=>
  int(42)
}

More info on PropertyNormalizer on https://symfony.com/doc/current/components/serializer.html#built-in-normalizers

Hope this helps

[tacman]

Thanks. I believe there's some way that deserializing does standard symfony property names, as PropertyAccessor does. Given

namespace src\Dto;
class Zone
{
    public $id;
    public string $storageHostname;
    public string $Region; // <-  boo, capitalized variable name! 
}

only $Region is populated, because of capitalization.

        $zoneArray = [
            'Id' => 1,
            'StorageHostname' => 'b2',
            'Region' => 'NY'
        ];
        $zoneDto = $serializer->denormalize($zoneArray, Zone::class);
        dd($zoneArray, $zoneDto);

[tacman]

One solution is to explicitly set each SerializedName, but I'm almost positive there's a way to do this automatically.

<?php

namespace src\Dto;
use Symfony\Component\Serializer\Annotation\SerializedName;

class Zone
{
    #[SerializedName('Id')]
    public $id;
    #[SerializedName('StorageHostname')]
    public string $storageHostname;
    #[SerializedName('Region')]
    public string $region;

}

1 in [AppController.php](file:///home/tac/g/sites/flickr-demo/src/Controller/AppController.php#L72) on line 72:
array:3 [▼
  "Id" => 1
  "StorageHostname" => "xyz"
  "Region" => "NY"
]
2 in [AppController.php](file:///home/tac/g/sites/flickr-demo/src/Controller/AppController.php#L72) on line 72:
[src\Dto\Zone](file:///home/tac/g/sites/flickr-demo/src/Dto/Zone.php#L6) {#902 ▼
  +id: 1
  +storageHostname: "xyz"
  +region: "NY"
}

[mbabker]

You can use name converters if you know that the objects are always going to use the same pattern (it looks like in your case you need to lowercase the first character, so it might work). See https://symfony.com/doc/current/components/serializer.html#converting-property-names-when-serializing-and-deserializing for that.

Otherwise, the explicit configuration through attributes on your DTO is going to be the best method.