feature #51 feat: allow any normalizable result from a tool (valtzu)

This PR was merged into the main branch.

Discussion
----------

feat: allow any normalizable result from a tool

| Q             | A
| ------------- | ---
| Bug fix?      | no
| New feature?  | yes
| Docs?         |
| Issues        |
| License       | MIT

Cherry picking php-llm/llm-chain#355

Commits
-------

006732d feat: allow any normalizable result from a tool (#355)

Author: OskarStark

src/agent/src/Toolbox/ToolResultConverter.php

@@ -11,32 +11,33 @@
 
 namespace Symfony\AI\Agent\Toolbox;
 
+use Symfony\Component\Serializer\Encoder\JsonEncoder;
+use Symfony\Component\Serializer\Normalizer\DateTimeNormalizer;
+use Symfony\Component\Serializer\Normalizer\JsonSerializableNormalizer;
+use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
+use Symfony\Component\Serializer\Serializer;
+use Symfony\Component\Serializer\SerializerInterface;
+
 /**
  * @author Christopher Hertel <[email protected]>
  */
 final readonly class ToolResultConverter
 {
-    /**
-     * @param \JsonSerializable|\Stringable|array<int|string, mixed>|float|string|\DateTimeInterface|null $result
-     */
-    public function convert(\JsonSerializable|\Stringable|array|float|string|\DateTimeInterface|null $result): ?string
-    {
-        if (null === $result) {
-            return null;
-        }
+    public function __construct(
+        private SerializerInterface $serializer = new Serializer([new JsonSerializableNormalizer(), new DateTimeNormalizer(), new ObjectNormalizer()], [new JsonEncoder()]),
+    ) {
+    }
 
-        if ($result instanceof \JsonSerializable || \is_array($result)) {
-            return json_encode($result, flags: \JSON_THROW_ON_ERROR);
+    public function convert(mixed $result): ?string
+    {
+        if (null === $result || \is_string($result)) {
+            return $result;
         }
 
-        if (\is_float($result) || $result instanceof \Stringable) {
+        if ($result instanceof \Stringable) {
             return (string) $result;
         }
 
-        if ($result instanceof \DateTimeInterface) {
-            return $result->format(\DATE_ATOM);
-        }
-
-        return $result;
+        return $this->serializer->serialize($result, 'json');
     }
 }

src/agent/tests/Toolbox/ToolResultConverterTest.php

@@ -16,6 +16,7 @@
 use PHPUnit\Framework\Attributes\Test;
 use PHPUnit\Framework\TestCase;
 use Symfony\AI\Agent\Toolbox\ToolResultConverter;
+use Symfony\AI\Fixtures\StructuredOutput\UserWithConstructor;
 
 #[CoversClass(ToolResultConverter::class)]
 final class ToolResultConverterTest extends TestCase
@@ -41,7 +42,7 @@ public static function provideResults(): \Generator
 
         yield 'string' => ['plain string', 'plain string'];
 
-        yield 'datetime' => [new \DateTimeImmutable('2021-07-31 12:34:56'), '2021-07-31T12:34:56+00:00'];
+        yield 'datetime' => [new \DateTimeImmutable('2021-07-31 12:34:56'), '"2021-07-31T12:34:56+00:00"'];
 
         yield 'stringable' => [
             new class implements \Stringable {
@@ -62,5 +63,16 @@ public function jsonSerialize(): array
             },
             '{"key":"value"}',
         ];
+
+        yield 'object' => [
+            new UserWithConstructor(
+                id: 123,
+                name: 'John Doe',
+                createdAt: new \DateTimeImmutable('2021-07-31 12:34:56'),
+                isActive: true,
+                age: 18,
+            ),
+            '{"id":123,"name":"John Doe","createdAt":"2021-07-31T12:34:56+00:00","isActive":true,"age":18}',
+        ];
     }
 }