Srijith Rajamohan, Ph.D.

sjster@gmail.com

srijithr.gitlab.io

Machine Learning/ Data Science

LinkedIn

GitHub

Twitter

Mathias Arlaud

mtarld

@matarld

les-tilleuls.coop

Network Map of Entities

Interactive Neighborhood Filtering

Summary

3 Coursera courses on Bayesian Modeling
Writing
- Articles on ML and DS on Databricks.com
- Publish articles on popular Medium publications such as Towards Data Science
- Thought-leadership articles
Work with Product teams
- ML Product team
- MLflow team
- PySpark team
Talks on MLflow, Deep Learning at Databricks, End-to-end ML at Scale, Bayesian Modeling
Worked with the SMEs on DL and NLP
Helped with the messaging architecture and redesign of the Spark website

Architecture

Our tiny panda

Doctrine
Schema

API Platform
Resource

PHP
Object

```
@matarld
```

```
@chalas_r
```

// src/Domain/Forest/Model/Panda.php

#[ORM\Entity]
#[ApiResource]
final class Panda
{
    public function __construct(
        private UuidInterface $uuid,
        // ...
        #[ORM\Column(type: 'int')]
        private int $hungerAmount,
    ) {
    }
    
    // ...
    
    public function isHungry(): bool
    {
        return $this->hungerAmount > self::HUNGERNESS_THRESHOLD;
    }

    public function feed(Bamboo $bamboo): void
    {
        $this->hungerAmount = min(0, $this->hunger - $bamboo->getSize());
    }
}

```
@matarld
```

```
@chalas_r
```

Decouple from Doctrine

#[ORM\Entity]
#[ApiResource]
final class Panda
{
    public function __construct(
        private UuidInterface $uuid,
        // ...
        #[ORM\Column(type: 'int')]
        private int $hunger,
    ) {
    }
    
    // ...
}

<!-- src/Infrastructure/Forest/Doctrine/Mapping/Panda.xml -->

<entity name="Acme\Domain\Forest\Model\Panda" table="panda">

    <field name="uuid" type="uuid" unique="true" />
    
    <!-- ... -->
    
    <field name="hungry" type="integer" />
 
</entity>

```
@matarld
```

```
@chalas_r
```

Decouple from API Platform

#[ApiResource]
final class Panda
{
    public function __construct(
        private UuidInterface $uuid,
        // ...
        private int $hunger,
    ) {
    }
    
    // ...
}

<!-- src/Infrastructure/Forest/ApiPlatform/Resource/Panda.xml -->

<resource class="Acme\Domain\Forest\Model\Panda">

  <itemOperations><!-- ... --></itemOperations>
  
  <collectionOperations><!-- ... --></collectionOperations>
 
</resource>

Finding pandas

```
> curl /api/pandas/{uuid}
```

API Platform
ReadListener

```
@matarld
```

```
@chalas_r
```

ChainItemDataProvider

```
[resourceClass, operationName, context]
```

Doctrine
ItemDataProvider

Finding pandas

```
> curl /api/pandas/{uuid}
```

API Platform
ReadListener

ChainItemDataProvider

```
[resourceClass, operationName, context]
```

DependencyInjection
Compiler Pass

Clearing tags

Our DataProvider

```
@matarld
```

```
@chalas_r
```

Command/Query pattern

```
@matarld
```

```
@chalas_r
```

Command

Domain

Infra

Query

Query based data provider

// src/Application/Forest/Query/FindPandaByUuidQuery.php

final class FindPandaByUuidQuery extends FindByUuidQuery
{
}

FindByUuidQuery

```
@matarld
```

```
@chalas_r
```

// src/Application/Forest/Query/FindPandaByUuidQueryHandler.php

use Acme\Domain\Forest\Repository\PandaRepository;

final class FindPandaByUuidQueryHandler implements QueryHandler
{
    public function __construct(private PandaRepository $repository) {}

    final public function __invoke(FindPandaByUuidQuery $query): ?Panda
    {
        return $this->repository->searchByUuid($query->uuid);
    }
}

Query based data provider

```
FindPandaByUuidQuery
```

Messenger
Query bus

```
Panda
```

A new resource operation attribute

```
@matarld
```

```
@chalas_r
```

<itemOperation name="get">
  <attribute name="query">FindPandaByUuidQuery</attribute>
</itemOperation>

// src/Infrastructure/Shared/ApiPlatform/DataProvider/ItemQueryDataProvider.php

final class ItemQueryDataProvider implements DataProviderInterface
{
    public function getItem(...): ?object
    {
        $queryClass = $this->resourceMetadataFactory
          ->create($resourceClass)
          ->getItemOperationAttribute($operationName, 'query');

        return $this->queryBus->ask(new $queryClass($identifiers['uuid']));
    }
    
    public function supports(...): bool { /* ... */}    
}

ItemQueryDataProvider

Check that we have a query attribute defined

Ensure that's a
```
FindByUuidQuery
```

DependencyInjection
Compiler Pass

Query based data provider

```
@matarld
```

```
@chalas_r
```

// src/Infrastructure/Shared/ApiPlatform/DataProvider/CollectionQueryDataProvider.php

final class CollectionQueryDataProvider implements DataProviderInterface
{
    public function getCollection(...): iterable
    {
        $queryClass = $this->resourceMetadataFactory
          ->create($resourceClass)
          ->getCollectionOperationAttribute($operationName, 'query');

        return $this->queryBus->ask($queryClass::fromContext($context));
    }
}

<collectionOperation name="get">
  <attribute name="query">FindPandasQuery</attribute>
</collectionOperation>

CollectionQueryDataProvider

Query based data provider

```
FindPandasQuery
```

```
Pandas
```

```
FindByCriteriaQuery
```

```
@matarld
```

```
@chalas_r
```

Custom DataProvider

Query based data provider

```
FindExtraterrialPandasQuery
```

Custom DataProvider
ExtraterrialPandaDataProvider

```
FindPandaByUuidQuery
```

CRUD DataProvider
ItemQueryDataProvider

// src/Infrastructure/Shared/ApiPlatform/DataPersister/DataPersister.php

final class DataPersister implements DataPersisterInterface
{
    public function persist(...): ?object
    {
        $commandClass = $this->resourceMetadataFactory->create($resourceClass)
            ->getOperationAttribute($context, 'command');

        return $this->commandBus->dispatch($commandClass::fromModel($data));

    }
    
    public function remove(...): void
    {
        $commandClass = $this->resourceMetadataFactory->create($resourceClass)
            ->getOperationAttribute($context, 'command');

        return $this->commandBus->dispatch($commandClass::fromModel($data));
    }
}

DataPersister

Command based data persister

```
@matarld
```

```
@chalas_r
```

```
PersistCommand
```

```
RemoveCommand
```

Command based data persister

Commands

// src/Application/Forest/Command/RemovePandaCommandHandler.php

final class RemovePandaCommandHandler implements CommandHandler
{
    public function __construct(private PandaRepository $repository) {}
    
    public function __invoke(RemovePandaCommand $command): void
    {
        $this->repository->remove($command->id());
    }
}

```
@matarld
```

```
@chalas_r
```

// src/Application/Forest/Command/RemovePandaCommand.php

final class RemovePandaCommand implements RemoveCommand
{
    public function __construct(private int $id) {}
    
    public static function fromModel(object $panda): self
    {
        return new self($panda->id());
    }
}

Command based data persister

Commands

```
@matarld
```

```
@chalas_r
```

<itemOperation name="remove">
  <attribute name="query">FindPandaByUuidQuery</attribute>
  <attribute name="command">RemovePandaCommand</attribute>
</itemOperation>

Delete it

Find a panda by its uuid

In a nutshell

ItemQueryDataProvider
FindByUuidQuery

CollectionQueryDataProvider
FindByCriteriaQuery

DataPersister
PersistCommand

DataPersister
RemoveCommand

API Platform
ReadListener

API Platform
WriteListener

```
@matarld
```

```
@chalas_r
```

Anemic models

Use case

final class Panda
{
    public function __construct(private string $name)
    {
    }
    
    public function getName(): string
    {
        return $this->name;
    }
    
    public function setName(string $name): void
    {
        $this->name = $name;
    }
}

```
{"name": "Pedro Panda"}
```

```
PATCH
```

Symfony
PropertyAccessor

Public properties

Setters

Constructor arguments

final class Panda
{
    public function __construct(private string $name)
    {
    }
    
    public function name(): string
    {
        return $this->name;
    }
    
    public function rename(string $firstname, string $lastname): void
    {
        $this->name = sprintf('%s %s', $firstname, $lastname);
    }
}

~~Public properties~~

~~Setters~~

~~Constructor arguments~~

```
@matarld
```

```
@chalas_r
```

Rich models

DTOs

Data Transfer Objects

```
@matarld
```

```
@chalas_r
```

DTOs

Payload and views

{
  "uuid": "...",
  "name": "Pedro Panda",
  "hungry": true
}

{
  "firstname": "Pedro",
  "lastname": "Panda"
}

final class Panda
{
    public function __construct(
        private UuidInterface $uuid,
        private string $name,
        private int $hunger,
    ) {
    }
    
    // ...
}

Payload

Model

View

Concatenate firstname and lastname

Convert hunger to "hungry" boolean

```
@matarld
```

```
@chalas_r
```

DTOs

API Platform configuration

<itemOperation name="get">
  
  <attribute name="input">Acme\Application\Forest\Payload\PandaPayload</attribute>
  <attribute name="output">Acme\Application\Forest\View\PandaView</attribute>
  
</itemOperation>

API Platform
DeserializeListener

API Platform
SerializeListener

```
@matarld
```

```
@chalas_r
```

Payload

Input DTO

// src/Application/Forest/Payload/PandaPayload.php

final class PandaPayload
{
    public function __construct(
        public readonly ?string $firstname = null,
        public readonly ?string $lastname = null,
    ) {
    }
}

// src/Domain/Forest/Model/Panda.php

final class Panda
{
    public function __construct(private string $name)
    {
    }
    
    public function rename(
        string $firstname, 
        string $lastname,
    ): void {
        $this->name = sprintf('%s %s', $firstname, $lastname);
    }
}

PandaPayloadDataTransformer
Use rename method

```
@matarld
```

```
@chalas_r
```

Payload

PayloadDataTransformer

// src/Infrastructure/Forest/ApiPlatform/DataTransformer/PandaPayloadDataTransformer.php

final class PandaPayloadDataTransformer implements DataTransformerInterface
{
    public function transform($payload, string $to, array $context = []) {
        $panda = $context['object_to_populate'] ?? new Panda();
        $panda->rename($payload->firstname, $payload->lastname);

        return $panda;
    }

    public function supportsTransformation($data, string $to, array $context = []): bool {
        return PandaPayload::class === ($context['input']['class'] ?? null)
            && Panda::class === $to;
    }
}

```
@matarld
```

```
@chalas_r
```

View

Output DTO

// src/Domain/Forest/Model/Panda.php

final class Panda
{
    public function __construct(
        private UuidInterface $uuid 
        private string $name,
        private int $hunger,
    ) {
    }
    
    public function isHungry(): bool
	{
        return $this->hunger > self::HUNGERNESS_THRESHOLD;
    }
}

// src/Application/Forest/View/PandaView.php

final class PandaView
{
    public function __construct(
        public readonly string $uuid,
        public readonly string $name,
        public readonly bool $hungry,
    ) {
    }
}

PandaViewDataTransformer
Cast uuid, use isHungry method

```
@matarld
```

```
@chalas_r
```

View

ViewDataTransformer

// src/Infrastructure/Forest/ApiPlatform/DataTransformer/PandaViewDataTransformer.php

final class PandaViewDataTransformer implements DataTransformer
{
    public function transform($panda, string $to, array $context = [])
    {
        return PandaView((string) $panda->uuid(), $panda->name(), $panda->isHungry());
    }

    public function supportsTransformation($data, string $to, array $context = []): bool
    {
        return PandaView::class === $to && $data instanceof Panda;
    }
}

```
@matarld
```

```
@chalas_r
```

To Summarize

```
@matarld
```

```
@chalas_r
```

API Platform is fully extensible.

Don't do this for your personal blog!

Take back control over the domain

Embrace complexity

Write more scalable & testable code

To Summarize

```
@matarld
```

```
@chalas_r
```

Thanks!

@matarld

@chalas_r

@coopTilleuls

Copy of [Forum PHP] DDD & APIP

By sjster

Copy of [Forum PHP] DDD & APIP

Srijith Rajamohan, Ph.D.

Network Map of Entities

Interactive Neighborhood Filtering

Summary

Architecture

Our tiny panda

Decouple from Doctrine

Decouple from API Platform

Finding pandas

Finding pandas

Command/Query pattern

Query based data provider

Query based data provider

Query based data provider

Query based data provider

Query based data provider

Command based data persister

Command based data persister

Command based data persister

In a nutshell

Anemic models

Rich models

DTOs

DTOs

DTOs

Payload

Payload

View

View

To Summarize

To Summarize

Thanks!

@matarld

@chalas_r

@coopTilleuls

Copy of [Forum PHP] DDD & APIP

More from sjster