Enable WebAPI interface to handle parameters through constructor

DTO setter methods are no more required, parameters can be handled through constructor for immutable state approach
A setter fallback is supported

Author: phoenix128

lib/internal/Magento/Framework/Webapi/ServiceInputProcessor.php

@@ -65,6 +65,11 @@ class ServiceInputProcessor implements ServicePayloadConverterInterface
      */
     private $serviceTypeToEntityTypeMap;
 
+    /**
+     * @var \Magento\Framework\ObjectManager\ConfigInterface
+     */
+    private $config;
+
     /**
      * Initialize dependencies.
      *
@@ -73,6 +78,7 @@ class ServiceInputProcessor implements ServicePayloadConverterInterface
      * @param AttributeValueFactory $attributeValueFactory
      * @param CustomAttributeTypeLocatorInterface $customAttributeTypeLocator
      * @param MethodsMap $methodsMap
+     * @param \Magento\Framework\ObjectManager\ConfigInterface $config
      * @param ServiceTypeToEntityTypeMap $serviceTypeToEntityTypeMap
      */
     public function __construct(
@@ -81,6 +87,7 @@ public function __construct(
         AttributeValueFactory $attributeValueFactory,
         CustomAttributeTypeLocatorInterface $customAttributeTypeLocator,
         MethodsMap $methodsMap,
+        \Magento\Framework\ObjectManager\ConfigInterface $config,
         ServiceTypeToEntityTypeMap $serviceTypeToEntityTypeMap = null
     ) {
         $this->typeProcessor = $typeProcessor;
@@ -90,6 +97,7 @@ public function __construct(
         $this->methodsMap = $methodsMap;
         $this->serviceTypeToEntityTypeMap = $serviceTypeToEntityTypeMap
             ?: \Magento\Framework\App\ObjectManager::getInstance()->get(ServiceTypeToEntityTypeMap::class);
+        $this->config = $config;
     }
 
     /**
@@ -153,6 +161,33 @@ public function process($serviceClassName, $serviceMethodName, array $inputArray
         return $inputData;
     }
 
+    /**
+     * @param string $className
+     * @param array $data
+     * @return array
+     * @throws \ReflectionException
+     */
+    private function getConstructorData(string $className, array $data): array
+    {
+        $preferenceClass = $this->config->getPreference($className);
+        $class = new ClassReflection($preferenceClass ?: $className);
+
+        $constructor = $class->getConstructor();
+        if ($constructor === null) {
+            return [];
+        }
+
+        $res = [];
+        $parameters = $constructor->getParameters();
+        foreach ($parameters as $parameter) {
+            if (isset($data[$parameter->getName()])) {
+                $res[$parameter->getName()] = $data[$parameter->getName()];
+            }
+        }
+
+        return $res;
+    }
+
     /**
      * Creates a new instance of the given class and populates it with the array of data. The data can
      * be in different forms depending on the adapter being used, REST vs. SOAP. For REST, the data is
@@ -173,9 +208,17 @@ protected function _createFromArray($className, $data)
         if (is_subclass_of($className, self::EXTENSION_ATTRIBUTES_TYPE)) {
             $className = substr($className, 0, -strlen('Interface'));
         }
-        $object = $this->objectManager->create($className);
 
+        // Primary method: assign to constructor parameters
+        $constructorArgs = $this->getConstructorData($className, $data);
+        $object = $this->objectManager->create($className, $constructorArgs);
+
+        // Secondary method: fallback to setter methods
         foreach ($data as $propertyName => $value) {
+            if (isset($constructorArgs[$propertyName])) {
+                continue;
+            }
+
             // Converts snake_case to uppercase CamelCase to help form getter/setter method names
             // This use case is for REST only. SOAP request data is already camel cased
             $camelCaseProperty = SimpleDataObjectConverter::snakeCaseToUpperCamelCase($propertyName);

lib/internal/Magento/Framework/Webapi/Test/Unit/ServiceInputProcessor/SimpleConstructor.php

@@ -0,0 +1,43 @@
+<?php
+/**
+ * Copyright © Magento, Inc. All rights reserved.
+ * See COPYING.txt for license details.
+ */
+namespace Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor;
+
+class SimpleConstructor
+{
+    /**
+     * @var int
+     */
+    private $entityId;
+
+    /**
+     * @var string
+     */
+    private $name;
+
+    public function __construct(
+        int $entityId,
+        string $name
+    ) {
+        $this->entityId = $entityId;
+        $this->name = $name;
+    }
+
+    /**
+     * @return int|null
+     */
+    public function getEntityId()
+    {
+        return $this->entityId;
+    }
+
+    /**
+     * @return string|null
+     */
+    public function getName()
+    {
+        return $this->name;
+    }
+}

lib/internal/Magento/Framework/Webapi/Test/Unit/ServiceInputProcessor/TestService.php

@@ -5,11 +5,6 @@
  */
 namespace Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor;
 
-use Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor\AssociativeArray;
-use Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor\DataArray;
-use Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor\Nested;
-use Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor\SimpleArray;
-
 class TestService
 {
     const DEFAULT_VALUE = 42;
@@ -25,6 +20,15 @@ public function simple($entityId, $name)
         return [$entityId, $name];
     }
 
+    /**
+     * @param \Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor\SimpleConstructor $simpleConstructor
+     * @return \Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor\SimpleConstructor
+     */
+    public function simpleConstructor(SimpleConstructor $simpleConstructor)
+    {
+        return $simpleConstructor;
+    }
+
     /**
      * @param int $entityId
      * @return string[]
@@ -34,6 +38,15 @@ public function simpleDefaultValue($entityId = self::DEFAULT_VALUE)
         return [$entityId];
     }
 
+    /**
+     * @param int $entityId
+     * @return string[]
+     */
+    public function constructorArguments($entityId = self::DEFAULT_VALUE)
+    {
+        return [$entityId];
+    }
+
     /**
      * @param \Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor\Nested $nested
      * @return \Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor\Nested

lib/internal/Magento/Framework/Webapi/Test/Unit/ServiceInputProcessorTest.php

@@ -9,6 +9,7 @@
 use Magento\Framework\Serialize\SerializerInterface;
 use Magento\Framework\Webapi\ServiceInputProcessor;
 use Magento\Framework\Webapi\ServiceTypeToEntityTypeMap;
+use Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor\SimpleConstructor;
 use Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor\WebapiBuilderFactory;
 use Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor\AssociativeArray;
 use Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor\DataArray;
@@ -59,8 +60,8 @@ protected function setUp()
         $this->objectManagerMock->expects($this->any())
             ->method('create')
             ->willReturnCallback(
-                function ($className) use ($objectManager) {
-                    return $objectManager->getObject($className);
+                function ($className, $arguments = []) use ($objectManager) {
+                    return $objectManager->getObject($className, $arguments);
                 }
             );
 
@@ -202,6 +203,22 @@ public function testNestedDataProperties()
         $this->assertEquals('Test', $details->getName());
     }
 
+    public function testSimpleConstructorProperties()
+    {
+        $data = ['simpleConstructor' => ['entityId' => 15, 'name' => 'Test']];
+        $result = $this->serviceInputProcessor->process(
+            \Magento\Framework\Webapi\Test\Unit\ServiceInputProcessor\TestService::class,
+            'simpleConstructor',
+            $data
+        );
+        $this->assertNotNull($result);
+        $arg = $result[0];
+
+        $this->assertTrue($arg instanceof SimpleConstructor);
+        $this->assertEquals(15, $arg->getEntityId());
+        $this->assertEquals('Test', $arg->getName());
+    }
+
     public function testSimpleArrayProperties()
     {
         $data = ['ids' => [1, 2, 3, 4]];