GraphQL Federation - resolve User type through API Gateway

executed.graphql

query MyQuery {
  # Returns only one result even if using @all on Tenant model
  getTenants(filters: {limit: 2}) {
    id
    name
  }
  
  getTenantById(id: "494796f0-4eee-4609-952c-8b1f816dc934") {
    name
  }
  
  getMe {
    firstname
    lastname
    tenant {
      id
      name
    }
  }
  
  getUserById(id: 1) {
    id
    firstname
    lastname
    tenant {
      id
      name
    }
  }
  
  getUsers {
    id
    firstname
    lastname
    
    tenant {
      id
      name
    }
  }
}

query.graphql

extend type Query @guard(with: ["jwt"]) {
    getTenantById(id: String! @eq): Tenant
        @find(model: "\\App\\Models\\Tenant")
        @can(ability: "view")
        
    getTenants(
        filters: TenantOptions @spread,
        orderBy: [OrderByClause!] @orderBy,
        trashed: Trash @trashed
    ): [Tenant]
        @all(model: "\\App\\Models\\Tenant", scopes: ["filters", "tree"])
        @can(ability: "viewAny")
}

result.json

{
  "data": {
    "getTenants": [
      {
        "id": "5078d9fe-df1c-4cf5-b3c4-c761b928a0ee",
        "name": "placeat-aut-ab"
      }
    ],
    "getTenantById": {
      "name": "eum-quod"
    },
    "getMe": {
      "firstname": null,
      "lastname": null,
      "tenant": {
        "id": "494796f0-4eee-4609-952c-8b1f816dc934",
        "name": "eum-quod"
      }
    },
    "getUserById": {
      "id": "1",
      "firstname": "Marianne",
      "lastname": "Koss",
      "tenant": {
        "id": "494796f0-4eee-4609-952c-8b1f816dc934",
        "name": "eum-quod"
      }
    },
    "getUsers": [
      {
        "id": "1",
        "firstname": "Marianne",
        "lastname": "Koss",
        "tenant": {
          "id": "494796f0-4eee-4609-952c-8b1f816dc934",
          "name": "eum-quod"
        }
      },
      {
        "id": "2",
        "firstname": "Chyna",
        "lastname": "Gusikowski",
        "tenant": {
          "id": "a873de56-9f23-4e28-9a54-19037392cb3c",
          "name": "recusandae-consequuntur"
        }
      }
    ]
  }
}

types.graphql

type Tenant {
  id: String!
  name: String!
}

""" Federation specific adjustments """
type User @key(fields: "id") @extends {
    id: ID! @external
    tenant: Tenant!
    # @can(ability: "view")
    # TODO somehow we need to pass the current tenant to check against as second argument to the view policy method
}

User.php

<?php

namespace App\GraphQL\Entities;

use App\Models\Tenant;
use GraphQL\Client;
use GraphQL\Query;

class User
{
    /**
     * @param array{__typename: string, id: int} $representation
     *
     * @return array
     */
    public function __invoke(array $representation): array
    {
        $client = new Client(
            'http://localhost:4000/graphql',
            [],
            [
                'connect_timeout' => 5,
                'timeout'         => 5,
                'headers'         => [
                    'Authorization' => request()->header('Authorization'),
                    'User-Agent'    => config('app.name'),
                ],
            ]
        );

        $gql = (new Query('getUserById'))
            ->setArguments([
                'id' => (int)$representation['id'],
            ])
            ->setSelectionSet(
                [
                    'id',
                    'tenant_id',
                    'firstname',
                    'lastname',
                    'email',
                    'active',
                    'timezone',
                    'language',
                ]
            );

        $results = $client->runQuery($gql, true);
        $user = $results->getData()['getUserById'];
        $tenant = Tenant::where('id', $user['tenant_id'])->first();

        return array_merge($representation, $user, ['tenant' => $tenant]);
    }
}