Patch to add interface to GraphQL Type decorator

type-resolver-interface.patch

From 27a47d83645fccc52fefe98c2e246e07ac78e84b Mon Sep 17 00:00:00 2001
From: Alexander Varwijk <alexander@getopensocial.com>
Date: Thu, 17 Jun 2021 17:40:10 +0200
Subject: [PATCH] Provide DecoratableTypeResolverInterface

The interface allows alternative but compatible decoratable type
resolvers to be created. It also provides an upgrade path for projects
that were already using the pattern.
---
 src/GraphQL/DecoratableTypeResolver.php       | 34 ++--------
 .../DecoratableTypeResolverInterface.php      | 62 +++++++++++++++++++
 2 files changed, 67 insertions(+), 29 deletions(-)
 create mode 100644 src/GraphQL/DecoratableTypeResolverInterface.php

diff --git a/src/GraphQL/DecoratableTypeResolver.php b/src/GraphQL/DecoratableTypeResolver.php
index 5fd2c89..80b8da4 100644
--- a/src/GraphQL/DecoratableTypeResolver.php
+++ b/src/GraphQL/DecoratableTypeResolver.php
@@ -3,36 +3,12 @@
 namespace Drupal\graphql\GraphQL;
 
 /**
- * A decoratable type resolver to resolve GraphQL interfaces to concrete types.
- *
- * Type resolvers should extend this class so that they can be chained in
- * schema extensions plugins.
- *
- * For example with the following class defined.
- * ```php
- * class ConcreteTypeResolver extends DecoratableTypeResolver {
- *
- *   protected function resolve($object) : ?string {
- *     return $object instanceof MyType ? 'MyType' : NULL;
- *   }
- * }
- * ```
- *
- * A schema extension would call:
- * ```php
- * $registry->addTypeResolver(
- *   'InterfaceType',
- *   new ConcreteTypeResolver($registry->getTypeResolver('InterfaceType'))
- * );
- * ```
- *
- * TypeResolvers should not extend other type resolvers but always extend this
- * class directly. Classes will be called in the reverse order of being added
- * (classes added last will be called first).
+ * A base class for decoratable type resolvers.
  *
  * @package Drupal\graphql\GraphQL
+ * @see \Drupal\graphql\GraphQL\DecoratableTypeResolverInterface
  */
-abstract class DecoratableTypeResolver {
+abstract class DecoratableTypeResolver implements DecoratableTypeResolverInterface {
 
   /**
    * The previous type resolver that was set in the chain.
@@ -44,10 +20,10 @@ abstract class DecoratableTypeResolver {
   /**
    * Create a new decoratable type resolver.
    *
-   * @param \Drupal\graphql\GraphQL\DecoratableTypeResolver|null $resolver
+   * @param \Drupal\graphql\GraphQL\DecoratableTypeResolverInterface|null $resolver
    *   The previous type resolver if any.
    */
-  public function __construct(self $resolver = NULL) {
+  public function __construct(DecoratableTypeResolverInterface $resolver = NULL) {
     $this->decorated = $resolver;
   }
 
diff --git a/src/GraphQL/DecoratableTypeResolverInterface.php b/src/GraphQL/DecoratableTypeResolverInterface.php
new file mode 100644
index 0000000..4e4ccf3
--- /dev/null
+++ b/src/GraphQL/DecoratableTypeResolverInterface.php
@@ -0,0 +1,62 @@
+<?php
+
+namespace Drupal\graphql\GraphQL;
+
+/**
+ * A decoratable type resolver to resolve GraphQL interfaces to concrete types.
+ *
+ * Type resolvers should extend this class so that they can be chained in
+ * schema extensions plugins.
+ *
+ * For example with the following class defined.
+ * ```php
+ * class ConcreteTypeResolver extends DecoratableTypeResolver {
+ *
+ *   protected function resolve($object) : ?string {
+ *     return $object instanceof MyType ? 'MyType' : NULL;
+ *   }
+ * }
+ * ```
+ *
+ * A schema extension would call:
+ * ```php
+ * $registry->addTypeResolver(
+ *   'InterfaceType',
+ *   new ConcreteTypeResolver($registry->getTypeResolver('InterfaceType'))
+ * );
+ * ```
+ *
+ * TypeResolvers should not extend other type resolvers but always extend this
+ * class directly. Classes will be called in the reverse order of being added
+ * (classes added last will be called first).
+ *
+ * @package Drupal\social_graphql\GraphQL
+ */
+interface DecoratableTypeResolverInterface {
+
+  /**
+   * Create a new decoratable type resolver.
+   *
+   * @param \Drupal\graphql\GraphQL\DecoratableTypeResolverInterface|null $resolver
+   *   The previous type resolver if any.
+   */
+  public function __construct(?self $resolver);
+
+  /**
+   * Allows this type resolver to be called by the GraphQL library.
+   *
+   * Takes care of chaining the various type resolvers together and invokes the
+   * `resolve` method for each concrete implementation in the chain.
+   *
+   * @param mixed $object
+   *   The object to resolve to a concrete type.
+   *
+   * @return string
+   *   The resolved GraphQL type name.
+   *
+   * @throws \RuntimeException
+   *   When a type was passed for which no type resolver exists in the chain.
+   */
+  public function __invoke($object) : string;
+
+}
-- 
2.30.0