Allow specifying a preferred object type to cast incoming array data to, if the data is array-ish.

Author: Crell

src/Attributes/MixedField.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Crell\Serde\Attributes;
+
+use Crell\AttributeUtils\SupportsScopes;
+use Crell\Serde\TypeField;
+use Attribute;
+
+#[Attribute(Attribute::TARGET_PROPERTY)]
+class MixedField implements TypeField, SupportsScopes
+{
+    public function __construct(
+        public readonly string $suggestedType,
+        protected readonly array $scopes = [null],
+    ) {}
+
+    public function scopes(): array
+    {
+        return $this->scopes;
+    }
+
+    public function acceptsType(string $type): bool
+    {
+        return $type === 'mixed';
+    }
+
+    public function validate(mixed $value): bool
+    {
+        return true;
+    }
+}

src/PropertyHandler/MixedExporter.php

@@ -6,6 +6,7 @@
 
 use Crell\Serde\Attributes\DictionaryField;
 use Crell\Serde\Attributes\Field;
+use Crell\Serde\Attributes\MixedField;
 use Crell\Serde\CollectionItem;
 use Crell\Serde\Deserializer;
 use Crell\Serde\Dict;
@@ -41,6 +42,12 @@ public function importValue(Deserializer $deserializer, Field $field, mixed $sou
         // it directly.
         $type = \get_debug_type($source[$field->serializedName]);
 
+        /** @var MixedField|null $typeField */
+        $typeField = $field->typeField;
+        if ($typeField && class_exists($typeField->suggestedType) && $type === 'array') {
+            $type = $typeField->suggestedType;
+        }
+
         return $deserializer->deserialize($source, Field::create(
             serializedName: $field->serializedName,
             phpType: $type,

tests/Records/MixedValObject.php

@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace Crell\Serde\Records;
+
+use Crell\Serde\Attributes\MixedField;
+
+class MixedValObject
+{
+    public function __construct(
+        #[MixedField(Point::class)]
+        public mixed $val
+    ) {}
+}

tests/SerdeTestCases.php

@@ -49,6 +49,7 @@
 use Crell\Serde\Records\MappedCollected\ThingC;
 use Crell\Serde\Records\MappedCollected\ThingList;
 use Crell\Serde\Records\MixedVal;
+use Crell\Serde\Records\MixedValObject;
 use Crell\Serde\Records\MultiCollect\ThingOneA;
 use Crell\Serde\Records\MultiCollect\ThingTwoC;
 use Crell\Serde\Records\MultiCollect\Wrapper;
@@ -1060,30 +1061,32 @@ public static function mixed_val_property_examples(): iterable
         yield 'float' => [new MixedVal(3.14)];
         yield 'sequence' => [new MixedVal(['a', 'b', 'c'])];
         yield 'dict' => [new MixedVal(['a' => 'A', 'b' => 'B', 'c' => 'C'])];
-        yield 'object' => [new MixedVal(new Point(1, 2, 3))];
     }
 
-    public function mixed_val_property_validate(mixed $serialized, mixed $data): void
+    #[Test,  DataProvider('mixed_val_property_object_examples')]
+    public function mixed_val_property_object(mixed $data): void
     {
-    }
+        $s = new SerdeCommon(formatters: $this->formatters);
 
-    /**
-     * This isn't a desired feature; it's just confirmation for the future why it is how it is.
-     */
-    #[Test]
-    public function mixed_val_object_does_not_serialize(): void
-    {
-        // MixedExporter sends the property value back through the Serialize pipeline
-        // a second time with a new Field definition. However, that trips the circular
-        // reference detection.  Ideally we will fix that somehow, but I'm not sure how.
-        // Importing an object to mixed will never work correctly.
-        $this->expectException(CircularReferenceDetected::class);
+        $serialized = $s->serialize($data, $this->format);
+
+        $this->mixed_val_property_validate($serialized, $data);
 
-        $data = new MixedVal(new Point(3, 4, 5));
+        $result = $s->deserialize($serialized, from: $this->format, to: MixedValObject::class);
 
-        $s = new SerdeCommon(formatters: $this->formatters);
+        self::assertEquals($data, $result);
+    }
 
-        $serialized = $s->serialize($data, $this->format);
+    public static function mixed_val_property_object_examples(): iterable
+    {
+        yield 'string' => [new MixedValObject('hello')];
+        yield 'int' => [new MixedValObject(5)];
+        yield 'float' => [new MixedValObject(3.14)];
+        yield 'object' => [new MixedValObject(new Point(1, 2, 3))];
+    }
+
+    public function mixed_val_property_validate(mixed $serialized, mixed $data): void
+    {
     }
 
     #[Test]