00_GridFieldRegistry.php

<?php

class GridFieldRegistry
{
  public function add($identifier, GridField $gridField)
  {
    if ($identifierIsNotUnique) { throw... }
    
    $this->registry[] = new GridFieldRegistration(
      $identifier,
      $gridField
    );
    
    public function getAll() { return $this->registry; }
  }
  
}

01_ProductsPage.php

<?php

class ProductsPage extends Page implements GridFieldProvider
{	


	// The class declares its gridfields and adds them to a registry
	public function provideGridFields(GridFieldRegistry $registry)
	{
		$registry->add(
			'FeaturedProducts',
			GridField::create(
				'FeaturedProducts',
				'Featured products',
				Product::get()->filter('Featured', true)
			)
		);
	}

	// The grid fields are fetched from the registry to build the form
	public function getCMSFields()
	{
		$fields = parent::getCMSFields();
		$fields->addFieldToTab(
			'Root.FeaturedProducts',
			// Helper method. Could be a trait added in the ancestry
			$this->getGridField('FeaturedProducts')
		);

		return $fields;
	}


}

02_UniversalScaffolder.php

<?php

// All dataObjects get exposed to GraphQL
class UniversalScaffolder implements ScaffoldingProvider
{

	public function provideGraphQLScaffolding(SchemaScaffolder $scaffolder)
	{
		foreach(ClassInfo::subclassesFor(DataObject::class) as $dataObjectClass) {
			$scaffolder->type($dataObjectClass)
				->addAllFields();
				->operation(SchemaScaffolder::ALL);

		}
	}	
}

03_GridFieldScaffolder.php

<?php

// GridFields will, at the very least, have special read operations
class GridFieldScaffolder implements ScaffoldingProvider
{

	public function __construct(GridFieldRegistry $registry);


	public function provideGraphQLScaffolding(SchemaScaffolder $scaffolder)
	{
		foreach ($this->registry->getAll() as $gridFieldRegistration) {
			
			$gridField = $gridFieldRegistration->getGridField();
			$identifier = $gridFieldRegistration->getIdentifier();
			$scaffolder->query(
				$identifier,
				$gridField->getList()->dataClass(), // Warning: assumes DataList
				function ($object, array $args, $context, ResolveInfo $info) use ($gridField) {
					return $gridField->getList();
				}
			);
		}
	}
}

04_LeftAndMain.php

<?php

class LeftAndMain ...
{
	// Collects all the providers and loads them into the registry
	someInitFunction()
	{
		$registry = Injector::inst()->get(GridFieldRegistry::class);
		foreach(ClassInfo::implementorsOf(GridFieldProvider::class) as $provider) {
			$provider->provideGridFields($registry);
		}
	}

	// Send all the GraphQL info to the client config to be loaded into Injector
	getClientConfig()
	{
		foreach(GridFieldRegistry::inst()->getAll() as $gridFieldRegistration) {
			$config['gridFieldQueries'][] = [
				'context' => $gridFieldRegistration->getInjectorContext(),
				'name' => $gridFieldRegistration->getIdentifier(),
				'fields' => $gridFieldRegistration->getDisplayedFields()
			]
		}
	}
}

05_registerGridFields.js

// load the queries into injector
config.gridFieldQueries.forEach(gridFieldQuery => {
	const { context, name, fields} = gridFieldQuery;
	const query = {
	  apolloConfig: {
	    props({ data }) {
	      return {
	        gridFieldData: data[name],
	      }
	    }
	  },
	  templateName: PROBABLY_SOMETHING_CUSTOM,
	  pagination: true,
	  params: {},
	  fields,
	};

	const queryName = `${name}Query`;
	Injector.register(queryName, query);
	Injector.transform(
	    `${name}-graphql`,
	    (updater) => {
	    	// context is the name of the GridField Injector, e.g.
	    	// GridField.ModelAdmin.EditForm.Products
	      updater.component(context, injectGraphql(queryName));
	    }		
	);
})

Notes:

• Context in FormBuilderLoader follows the pattern [FieldType].[FormIdentifier].[FieldName]. We don't really have enough in a DataObject definition to determine that context. We may need to enhance the way the GridField component creates its context name and/or beef up the way injector can wildcard context, e.g. updater.component(GridField.**.${myGridFieldIdentifier}, injectGraphql(...)) (using a double ** to match any depth).

• You wouldn't need GridFieldProvider if getCMSFields is deterministic.

• Thought should be given on how to streamline the 80% use case, which is $myObj->SomeRelationship()

• Not sure how we would handle the query template. We have to afford customisations for adding params.

• Maybe the third param of theGridField constructor becomes a closure, and instead of getList(), we have getResolver()