feat: Add a custom encoder in Serializer

src/Serializer.php

@@ -69,6 +69,11 @@ class Serializer
     private $messageTypeTransformers;
     private $decodeFieldTransformers;
     private $decodeMessageTypeTransformers;
+    // Array of key-value pairs which specify a custom encoding function.
+    // The key is the proto class and the value is the function
+    // which will be used to convert the proto instead of the
+    // encodeMessage method from the Serializer class.
+    private $customEncoders;
 
     private $descriptorMaps = [];
 
@@ -84,12 +89,14 @@ public function __construct(
         $fieldTransformers = [],
         $messageTypeTransformers = [],
         $decodeFieldTransformers = [],
-        $decodeMessageTypeTransformers = []
+        $decodeMessageTypeTransformers = [],
+        $customEncoders = [],
     ) {
         $this->fieldTransformers = $fieldTransformers;
         $this->messageTypeTransformers = $messageTypeTransformers;
         $this->decodeFieldTransformers = $decodeFieldTransformers;
         $this->decodeMessageTypeTransformers = $decodeMessageTypeTransformers;
+        $this->customEncoders = $customEncoders;
     }
 
     /**
@@ -101,6 +108,14 @@ public function __construct(
      */
     public function encodeMessage($message)
     {
+        $cls = get_class($message);
+
+        // If we have supplied a customEncoder for this class type,
+        // then we use that instead of the general encodeMessage definition.
+        if (array_key_exists($cls, $this->customEncoders)) {
+            $func = $this->customEncoders[$cls];
+            return call_user_func($func, $message);
+        }
         // Get message descriptor
         $pool = DescriptorPool::getGeneratedPool();
         $messageType = $pool->getDescriptorByClassName(get_class($message));

tests/Tests/Unit/SerializerTest.php

@@ -291,4 +291,64 @@ public function testSpecialEncodingDecodingByFieldType()
         $this->assertEqualsWithDelta($data['blue'], $array['blue'], 0.0000001);
         $this->assertEqualsWithDelta($data['alpha']['value'], $array['alpha']['value'], 0.0000001);
     }
+
+    /**
+     * @dataProvider customEncoderProvider
+     */
+    public function testCustomEncoderForEncodeMessage($customEncoder, $protoObj, $expectedData)
+    {
+        $serializer = new Serializer([], [], [], [], $customEncoder);
+
+        $data = $serializer->encodeMessage($protoObj);
+        array_walk($expectedData, function ($val, $key, $expectedData) {
+            $this->assertEquals($val, $expectedData[$key]);
+        }, $expectedData);
+    }
+
+    public function customEncoderProvider()
+    {
+        $original = [
+            'red' => 50.0,
+            'blue' => 50.0
+        ];
+
+        $expected = [
+            'red' => 100.0,
+            'blue' => 100.0
+        ];
+
+        return  [
+            [
+                [
+                    Color::class => function ($message) {
+                        return [
+                            'red' => $message->getRed() * 2,
+                            'blue' => $message->getBlue() * 2
+                        ];
+                    }
+                ],
+                new Color($original),
+                $expected
+            ],
+            [
+                // When no custom encoder is supplied, the encodeMessage will return the data
+                // that is passed into the proto
+                [
+                ],
+                new Color($original),
+                $original
+            ],
+            [
+                // When a custom encoder for a different protois supplied,
+                // the encodeMessage will return the data as if no custom encoder was supplied
+                [
+                    Status::class => function ($message) {
+                        return ['foo' => 'bar'];
+                    }
+                ],
+                new Color($original),
+                $original
+            ]
+        ];
+    }
 }