api_client.php

<?php

class ApiClient
	{
	/**
	 * @return Project[]
	 */
	public function getProjects(): array
		{
		$projects = [];
		$response = $this->client->get('https://some-awesome.api/projects');
		$projectCollection = $this->serializer->deserialize($response->getBody()->getContent(), ProjectCollection::class, 'json');
		if (!empty($collection->getResult()))
			{
			foreach ($collection->getResult() as $project)
				{
				if ($project->isOnSale())
					{
					$projects[] = $project;
					}
				}
			}
		
		return $projects;
		}
	
	public function addNewProject(Project $project)
		{
		$this->client->post('https://some-awesome.api/projects', [
			'body' => $this->serializer->serialize($project, 'json')
			]);
		}
	}

project.php

<?php

use Symfony\Component\Serializer\Annotation\SerializedName;

class Project
  {
  /**
   * @SerializedName("Id")
   * @var int
   */
  private $internalId;
  
  /**
   * @SerializedName("Name")
   * @var string
   */
  private $title;
  
  /**
   * @SerializedName("Quality")
   * @var float
   */
  private $quality;
  
  // getters and setters
  }

project_collection.php

<?php

use Symfony\Component\Serializer\Annotation\SerializedName;

class ProjectCollection
  {
  /**
   * @SerializedName("Result")
   * @var Project[]
   */
  private $result;
  
  /**
   * @return Project[]|null
   */
  public function getResult(): ?array
    {
    return $this->result;
    }
	
  /**
   * @param Project[] $results
   */
  public function setResult(array $result)
    {
    $this->result = $result;
    }
  }

PS I recommend that you inject the serializer in your controller/service (typecast it to SerializerInterface) instead of constructing it, like in your gist. That way, you'll be sure the extractor is registered in the Serializer

Yes, finally I got Project objects returned now it works like I expected. Gonna try to fix the mapping. I also changed the example to use the SerializerInterface type hint as you suggested. The default serializer-pack of the website-skeleton installs all (hidden) dependencies.

array:3 [▼
  0 => App\Model\Project {#699 ▼
    -title: "Project A"
    -sale: "1"
  }
  1 => App\Model\Project {#693 ▼
    -title: "Project B"
    -sale: "1"
  }
  2 => App\Model\Project {#692 ▼
    -title: "Project C"
    -sale: "0"
  }
]

Great! I'm glad it worked! I learned a lot through your use case, thanks!
I've updated the article to suggest symfony/serializer-pack and mentioned you in the DocBlock parsing ;)

Thx I learned a lot as well. And appreciate the mention. I am going to use this further in my project.