Use InputUnionType for embedded entities

Author: alanpoulain

features/graphql/mutation.feature

@@ -106,6 +106,22 @@ Feature: GraphQL mutation support
     And the JSON node "data.createDummy.arrayData[1]" should be equal to baz
     And the JSON node "data.createDummy.clientMutationId" should be equal to "myId"
 
+  Scenario: Create an item with an embedded field
+    When I send the following GraphQL request:
+    """
+    mutation {
+      createRelatedDummy(input: {_id: 2, symfony: "symfony", embeddedDummy: {dummyName: "Embedded"}, clientMutationId: "myId"}) {
+        id
+        clientMutationId
+      }
+    }
+    """
+    Then the response status code should be 200
+    And the response should be in JSON
+    And the header "Content-Type" should be equal to "application/json"
+    And the JSON node "data.createRelatedDummy.id" should be equal to "/related_dummies/2"
+    And the JSON node "data.createRelatedDummy.clientMutationId" should be equal to "myId"
+
   @dropSchema
   Scenario: Delete an item through a mutation
     When I send the following GraphQL request:

src/GraphQl/Type/SchemaBuilder.php

@@ -16,6 +16,7 @@
 use ApiPlatform\Core\Exception\ResourceClassNotFoundException;
 use ApiPlatform\Core\GraphQl\Resolver\Factory\ResolverFactoryInterface;
 use ApiPlatform\Core\GraphQl\Serializer\ItemNormalizer;
+use ApiPlatform\Core\GraphQl\Type\Definition\InputUnionType;
 use ApiPlatform\Core\GraphQl\Type\Definition\IterableType;
 use ApiPlatform\Core\Metadata\Property\Factory\PropertyMetadataFactoryInterface;
 use ApiPlatform\Core\Metadata\Property\Factory\PropertyNameCollectionFactoryInterface;
@@ -335,13 +336,24 @@ private function convertType(Type $type, bool $input = false, string $mutationNa
                 break;
             case Type::BUILTIN_TYPE_ARRAY:
             case Type::BUILTIN_TYPE_ITERABLE:
-                if (!isset($this->graphqlTypes['#iterable'])) {
-                    $this->graphqlTypes['#iterable'] = new IterableType();
-                }
-                $graphqlType = $this->graphqlTypes['#iterable'];
+                $graphqlType = $this->getIterableType();
                 break;
             case Type::BUILTIN_TYPE_OBJECT:
-                if (($input && $depth > 0) || is_a($type->getClassName(), \DateTimeInterface::class, true)) {
+                if ($input && $depth > 0) {
+                    if (!isset($this->graphqlTypes['#stringIterableUnionInput'])) {
+                        $this->graphqlTypes['#stringIterableUnionInput'] = new InputUnionType([
+                            'name' => 'StringIterableUnionInput',
+                            'description' => 'Resource\'s IRI or data (embedded entities or when updating a related existing resource)',
+                            'types' => [
+                                GraphQLType::string(),
+                                $this->getIterableType(),
+                            ],
+                        ]);
+                    }
+                    $graphqlType = $this->graphqlTypes['#stringIterableUnionInput'];
+                    break;
+                }
+                if (is_a($type->getClassName(), \DateTimeInterface::class, true)) {
                     $graphqlType = GraphQLType::string();
                     break;
                 }
@@ -492,6 +504,15 @@ private function getResourcePaginatedCollectionType(string $resourceClass, Graph
         return $this->graphqlTypes[$resourceClass]['connection'] = new ObjectType($configuration);
     }
 
+    private function getIterableType(): IterableType
+    {
+        if (!isset($this->graphqlTypes['#iterable'])) {
+            $this->graphqlTypes['#iterable'] = new IterableType();
+        }
+
+        return $this->graphqlTypes['#iterable'];
+    }
+
     private function isCollection(Type $type): bool
     {
         return $type->isCollection() && Type::BUILTIN_TYPE_OBJECT === $type->getBuiltinType();