Domain-Driven Design and

API Platform 3

@matarld

@chalas_r

Mathias Arlaud

@matarld

mtarld

les-tilleuls.coop

Robin Chalas

@chalas_r

les-tilleuls.coop

chalasr

DDD is not prescriptive.

Mathias Verraes - What is Domain Driven Design

@matarld

@chalas_r

DDD ≠ RAD

“Domain-Driven Design is not a fast way to build software.

William Durand - DDD with Symfony 2: Making things clear

However, it is able to ease your life when you have to deal with complex business expectations.”

@matarld

@chalas_r

└──   src
      ├──   Provider
      │
      ├──   Processor
      │
      ├──   Entity
      │     └──   Book.php
      │
      └──   Repository
            └──   BookRepository.php

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@chalas_r

Directory structure

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@chalas_r

└──   src
      └──   BookStore
            ├──   Application
            │     ├──   Command
            │     │     ├──   DiscountBookCommand.php
            │     │     └──   DiscountBookCommandHandler.php
            │     └──   Query
            ├──   Domain
            │     ├──   Model
            │     │     └──   Book.php
            │     └──   Repository
            │           └──   BookRepository.php
            └──   Infrastructure
                  ├──   ApiPlatform
                  └──   Doctrine

Directory structure

Domain

Models, Value objects, Events, Repositories

Application

Application services, DTOs, Commands, Queries

Infrastructure

Controllers, Databases, Caches, Vendors

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@chalas_r

Hexagonal architecture

Domain integrity is preserved

Code is more testable

Technological decisions can be deferred

Domain is agnostic to the outside world

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@chalas_r

Hexagonal architecture

GET /books

GET /books/cheapests

PATCH /books/{id}

DELETE /books/{id}

POST /books/anonymize

POST /books/{id}/discount

[...]

namespace App\BookStore\Domain\Model;

final class Book
{
    public readonly BookId $id;

    public function __construct(
        public BookName $name,
        public BookDescription $description,
        public Author $author,
        public Price $price,
    ) {
        $this->id = new BookId();
    }
}

@matarld

@chalas_r

Reading is dreaming with open eyes...

namespace App\BookStore\Domain\Model;

final class Book
{
    public readonly BookId $id;

    public function __construct(
        public BookName $name,
        public BookDescription $description,
        public Author $author,
        public Price $price,
    ) {
        $this->id = new BookId();
    }
}

11 warnings

7  errors

#[ApiResource(operations: [
    new Get(),
    new Post('/books/{id}/discount'),
])]
final class Book
{
    public function __construct(
        #[Groups(['book:create'])]
        #[Assert\NotBlank]
        public ?BookId $id = null;
        
        #[Groups(['book:create', 'book:update'])]
        #[Assert\Positive]
        public ?Price $price = null,

        // ...
    ) {
        $this->id = $id ?? new BookId();
    }
}

@matarld

@chalas_r

Simple as sugar cookies?

namespace App\BookStore\Infrastructure\ApiPlatform\Resource;

#[ApiResource(operations: [new Get(), new Post('...')])]
final class BookResource
{
    public function __construct(
        #[ApiProperty(identifier: true)]
        #[Groups(['book:create'])]
        #[Assert\NotBlank]
        public ?Uuid $id = null;

        // ...
    ) {
    }
}

namespace App\BookStore\Domain\Model;

final class Book
{
    public readonly BookId $id;

    public function __construct(
        public BookName $name,
        public BookDescription $description,
        public Author $author,
        public Price $price,
    ) {
        // ...
    }
}

Model

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From API Platform to the Domain

API Resource

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The Application Layer

Command/Query bus

Application layer

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Command/Query pattern

Model

Domain layer

API resource

Infrastructure layer

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@chalas_r

Find the

cheapest books.

Use case #1

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@chalas_r

Query and QueryHandler

namespace App\BookStore\Application\Query;

final class FindCheapestBooksQueryHandler
{
  public function __construct(
      private BookRepositoryInterface $bookRepository
  ) {
  }

  public function __invoke(FindCheapestBooksQuery $query)
  {
    return $this->bookRepository
      ->withCheapestsFirst()
      ->withPagination(1, $query->size);
  }
}

QueryHandler

namespace App\BookStore\Application\Query;

final class FindCheapestBooksQuery
{
    public function __construct(
        public readonly int $size = 10,
    ) {
    }
}

Query

GET /books/cheapest

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@chalas_r

API Platform providers

FindCheapestBooksQuery

Provider

new GetCollection('/books/cheapest')

Operation

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@chalas_r

Let's hold the query in the operation!

API Platform providers

GET /books/cheapest

FooProvider

CheapestBooksProvider

BarProvider

new QueryOperation(
 '/books/cheapest',
 FindCheapestBooksQuery::class,
)

"Query" operation

new GetCollection('/books/cheapest')

Operation

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@chalas_r

Can we

do better?

Spoiler: yes

@matarld

@chalas_r

Let's hold the provider in the operation!

Providers - the new way

GET /books/cheapest

FooProvider

CheapestBooksProvider

BarProvider

new GetCollection(
 '/books/cheapest',
 provider: CheapestBooksProvider::class,
)

Operation

new GetCollection('/books/cheapest')

Operation

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@chalas_r

Domain

Query providers' content

namespace App\BookStore\Infrastructure\ApiPlatform\State\Provider;

final class CheapestBooksProvider implements ProviderInterface
{
  /** @return list<BookResource> */
  public function provide(...): object|array|null
  {
    /** @var iterable<Book> $models */
    $models = $this->queryBus->ask(new FindCheapestBooksQuery());

    $resources = [];
    foreach ($models as $m) {
      $resources[] = BookResource::fromModel($m);
    }

    return $resources;
  }
}

Appli

Infra

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@chalas_r

Applying

a discount.

Use case #2

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@chalas_r

Command and CommandHandler

namespace App\BookStore\Application\Command;

final class DiscountBookCommandHandler
{
  public function __construct(
    private BookRepositoryInterface $bookRepository,
  ) {
  }

  public function __invoke(DiscountBookCommand $command)
  {
    // my super complex logic
  }
}

CommandHandler

namespace App\BookStore\Application\Command;

final class DiscountBookCommand
{
    public function __construct(
        public readonly Uuid $id,
        public readonly int $amount,
    ) {
    }
}

Command

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@chalas_r

Processors - the new way

POST /books/{id}/discount

DiscountBookProcessor

new Post(
  '/books/{id}/discount',
  input: DiscountBookPayload::class,
  provider: BookItemProvider::class,
  processor: DiscountBookProcessor::class,
)

Operation

new Post(
  '/books/{id}/discount',
  input: DiscountBookPayload::class,
  provider: BookItemProvider::class,
)

Operation

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@chalas_r

Domain

Command processors' content

namespace App\BookStore\Infrastructure\ApiPlatform\State\Provider;

final class DiscountBookProcessor implements ProcessorInterface
{
  /**
   * @var DiscountBookPayload $data
   * @return BookResource
   */
  public function process(...): mixed
  {
    $this->commandBus->dispatch(new DiscountBookCommand(
      id: $context['previous_data']->id,
      discountPercentage: $data->discountPercentage,
    ));
    
    $model = $this->queryBus->ask(new FindBookQuery($command->id));

    return BookResource::fromModel($model);
  }
}

Appli

Infra

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@chalas_r

Subscribing to

new books.

Use case #3

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@chalas_r

Bounded contexts

Subscription

BookStore

Payment

Hexagonal

RAD

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@chalas_r

RAD API Platform CRUD

namespace App\Subscription\Entity;

#[ApiResource(operations: [new GetCollection(), new Post()])]
#[ORM\Entity]
class Subscription
{
    public function __construct(
        #[ApiProperty(identifier: true)]
        #[ORM\Id]
        #[ORM\Column(type: 'uuid', unique: true)]
        public ?Uuid $id = null,

        #[Assert\NotBlank(groups: ['create'])]
        #[Assert\Email(groups: ['create', 'Default'])]
        #[ORM\Column(name: 'name', nullable: false)]
        public ?string $email = null,
    ) {
    }
}

@matarld

@chalas_r

├──   BookStore
│   ├──   Application
│   │   ├──   Command
│   │   │   ├──   CreateSubscriptionCommand.php
│   │   │   ├──   CreateSubscriptionCommandHandler.php
│   │   │   ├──   DiscountBookCommand.php
│   │   │   ├──   DiscountBookCommandHandler.php
│   │   │   └── ...
│   │   └──   Query
│   │       ├──   FindBookQuery.php
│   │       ├──   FindBookQueryHandler.php
│   │       ├──   FindCheapestBooksQuery.php
│   │       ├──   FindCheapestBooksQueryHandler.php
│   │       └── ...
│   ├──   Domain
│   └──   Infrastructure
└──   Subscription

├──   BookStore
│   ├──   Application
│   ├──   Domain
│   │   ├──   Model
│   │   │   ├──   Book.php
│   │   │   └──   Subscription.php
│   │   └──   Repository
│   │       ├──   BookRepositoryInterface.php
│   │       └──   SubscriptionRepositoryInterface.php
│   └──   Infrastructure
└──   Subscription

├──   BookStore
└──   Subscription
    └──   Entity
        └──   Subscription.php

├──   BookStore
│   ├──   Application
│   ├──   Domain
│   └──   Infrastructure
│       └──   ApiPlatform
│           ├──   Payload
│           │   └──   DiscountBookPayload.php
│           ├──   Resource
│           │   └──   BookResource.php
│           └──   State
│               ├──   Processor
│               │   ├──   AnonymizeBooksProcessor.php
│               │   └──   DiscountBookProcessor.php
│               └──   Provider
│                   ├──   BookItemProvider.php
│                   └──   CheapestBooksProvider.php
└──   Subscription

Wrap it up

Domain

Application

Infrastructure

RAD

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@chalas_r

Wrap it up

Business hexagonal

#[ApiResource(
  operations: [
    new GetCollection(
      '/books/cheapest',
      provider: CheapestBooksProvider::class,
    ),
    new Post(
      '/books/{id}/discount',
      input: DiscountBookPayload::class,
      provider: BookItemProvider::class,
      processor: DiscountBookProcessor::class,
    ),
  ],
)]
final class BookResource

Hexagonal business

RAD CRUD

#[ApiResource(
  operations: [new Get(), new Post()],
)]
final class Subscription

@matarld

@chalas_r

And it just works!

Domain-Driven Design and

API Platform 3

Mathias Arlaud

Robin Chalas

DDD is not prescriptive.​

DDD ≠ RAD

“Domain-Driven Design is not a fast way to build software.​

However, it is able to ease your life when you have to deal with complex business expectations​.”

Directory structure

Directory structure

Directory structure

Directory structure

Directory structure

Directory structure

Domain

Application

Infrastructure

Hexagonal architecture

Hexagonal architecture

Reading is dreaming with open eyes...

Simple as sugar cookies?

Model

From API Platform to the Domain

API Resource

The Application Layer

Command/Query bus

Command/Query pattern

Model

API resource

Find the

cheapest books.​

Query and QueryHandler

QueryHandler

Query

API Platform providers

Operation

API Platform providers

"Query" operation

Operation

Can we

do better?​

Providers - the new way

Operation

Operation

Query providers' content

Applying

a discount.​

Command and CommandHandler

CommandHandler

Command

Processors - the new way

Operation

Operation

Command processors' content

Subscribing to

new books.​

Bounded contexts

RAD API Platform CRUD

Wrap it up

Domain

Application

Infrastructure

RAD

Wrap it up

Business hexagonal

Hexagonal business

RAD CRUD

And it just works!

Thanks!

[APIP Con] DDD & API-P 3

More from Robin Chalas

DDD is not prescriptive.

“Domain-Driven Design is not a fast way to build software.

However, it is able to ease your life when you have to deal with complex business expectations.”

cheapest books.

do better?

a discount.

new books.