- update validation rule to keep updated with suggestions in graphql/graphql-spec#825

Author: jasonbahl

src/Validator/Rules/OneOfInputObjectsRule.php

@@ -32,9 +32,16 @@ public function getVisitor(QueryValidationContext $context): array
                 }
 
                 $providedFields = [];
+                $nullFields = [];
+
                 foreach ($node->fields as $fieldNode) {
                     $fieldName = $fieldNode->name->value;
                     $providedFields[] = $fieldName;
+
+                    // Check if the field value is explicitly null
+                    if ($fieldNode->value->kind === NodeKind::NULL) {
+                        $nullFields[] = $fieldName;
+                    }
                 }
 
                 $fieldCount = count($providedFields);
@@ -44,11 +51,26 @@ public function getVisitor(QueryValidationContext $context): array
                         static::oneOfInputObjectExpectedExactlyOneFieldMessage($namedType->name),
                         [$node]
                     ));
-                } elseif ($fieldCount > 1) {
+
+                    return;
+                }
+
+                if ($fieldCount > 1) {
                     $context->reportError(new Error(
                         static::oneOfInputObjectExpectedExactlyOneFieldMessage($namedType->name, $fieldCount),
                         [$node]
                     ));
+
+                    return;
+                }
+
+                // At this point, $fieldCount === 1
+                if (count($nullFields) > 0) {
+                    // Exactly one field provided, but it's null
+                    $context->reportError(new Error(
+                        static::oneOfInputObjectFieldValueMustNotBeNullMessage($namedType->name, $nullFields[0]),
+                        [$node]
+                    ));
                 }
             },
         ];
@@ -62,4 +84,9 @@ public static function oneOfInputObjectExpectedExactlyOneFieldMessage(string $ty
 
         return "OneOf input object '{$typeName}' must specify exactly one field, but {$providedCount} fields were provided.";
     }
+
+    public static function oneOfInputObjectFieldValueMustNotBeNullMessage(string $typeName, string $fieldName): string
+    {
+        return "OneOf input object '{$typeName}' field '{$fieldName}' must be non-null.";
+    }
 }

tests/Type/OneOfInputObjectTest.php

@@ -124,6 +124,13 @@ public function testOneOfInputObjectSchemaValidation(): void
         self::assertNotEmpty($result->errors ?? []);
         self::assertCount(1, $result->errors);
         self::assertStringContainsString('must specify exactly one field', $result->errors[0]->getMessage());
+
+        // Invalid query with null field value
+        $nullQuery = '{ test(input: { stringField: null }) }';
+        $result = GraphQL::executeQuery($schema, $nullQuery);
+        self::assertNotEmpty($result->errors ?? []);
+        self::assertCount(1, $result->errors);
+        self::assertStringContainsString('must be non-null', $result->errors[0]->getMessage());
     }
 
     public function testOneOfIntrospection(): void