Add support for schema generation (#37)

* Create the SchemaGenerator class and define the SchemaAttributeReader
 and SchemaAttribute interfaces. This allows us to support php8 attributes in the future.
* Create the AnnotationReader adapter that parses class annotations.
* Add documentation and further examples.
* Increment the miminum phpstan version.
* Refactor Schema builder to use constants instead of literal strings.

Thanks to @fcoedno for the contribution!

Author: xico42

README.md

@@ -380,6 +380,72 @@ Schema::record()
     ->parse();
 ```
 
+## Schema generator
+
+Besides providing a fluent api for defining schemas, we also provide means of generating schema from 
+class metadata (annotations). For this to work, you have to install the `doctrine/annotations` package.
+
+```php
+<?php
+
+use FlixTech\AvroSerializer\Objects\DefaultSchemaGeneratorFactory;
+use FlixTech\AvroSerializer\Objects\Schema\Generation\Annotations as SerDe;
+
+/**
+ * @SerDe\AvroType("record")
+ * @SerDe\AvroName("user")
+ */
+class User
+{
+    /**
+     * @SerDe\AvroType("string")
+     * @var string
+     */
+    private $firstName;
+
+    /**
+     * @SerDe\AvroType("string")
+     * @var string
+     */
+    private $lastName;
+
+    /**
+     * @SerDe\AvroType("int")
+     * @var int
+     */
+    private $age;
+
+    public function __construct(string $firstName, string $lastName, int $age)
+    {
+        $this->firstName = $firstName;
+        $this->lastName = $lastName;
+        $this->age = $age;
+    }
+
+    public function getFirstName(): string
+    {
+        return $this->firstName;
+    }
+
+    public function getLastName(): string
+    {
+        return $this->lastName;
+    }
+
+    public function getAge(): int
+    {
+        return $this->age;
+    }
+}
+
+$generator = DefaultSchemaGeneratorFactory::get();
+
+$schema = $generator->generate(User::class);
+$avroSchema = $schema->parse();
+```
+
+Further examples on the possible annotations can be seen in the [test case](test/Objects/Schema/Generation/SchemaGeneratorTest.php).
+
 ## Examples
 
 This library provides a few executable examples in the [examples](examples) folder. You should have a look to get an

composer.json

@@ -31,10 +31,11 @@
   },
   "require-dev": {
     "phpunit/phpunit": "~7.0,<8.0",
-    "phpstan/phpstan": "^0.12",
+    "phpstan/phpstan": "^0.12.24",
     "phpbench/phpbench": "~0.9",
     "vlucas/phpdotenv": "~2.4",
-    "symfony/serializer": "^3.4|^4.3"
+    "symfony/serializer": "^3.4|^4.3",
+    "doctrine/annotations": "^1.10"
   },
   "autoload": {
     "psr-4": {
@@ -48,7 +49,8 @@
     ]
   },
   "suggest": {
-    "symfony/serializer": "To integrate avro-serde-php into symfony ecosystem"
+    "symfony/serializer": "To integrate avro-serde-php into symfony ecosystem",
+    "doctrine/annotations": "To enable the generation of avro schemas from annotations"
   },
   "autoload-dev": {
     "psr-4": {

examples/SchemaGenerator.php

@@ -0,0 +1,145 @@
+<?php
+
+declare(strict_types=1);
+
+namespace FlixTech\AvroSerializer\Examples;
+
+use Dotenv\Dotenv;
+use FlixTech\AvroSerializer\Integrations\Symfony\Serializer\AvroSerDeEncoder;
+use FlixTech\AvroSerializer\Objects\DefaultRecordSerializerFactory;
+use FlixTech\AvroSerializer\Objects\DefaultSchemaGeneratorFactory;
+use PHPUnit\Framework\Assert;
+use Symfony\Component\Serializer\Normalizer\PropertyNormalizer;
+use Symfony\Component\Serializer\Serializer;
+use FlixTech\AvroSerializer\Objects\Schema\Generation\Annotations as SerDe;
+
+require __DIR__ . '/../vendor/autoload.php';
+
+$dotEnv = new Dotenv(__DIR__ . '/..');
+$dotEnv->load();
+$dotEnv->required('SCHEMA_REGISTRY_HOST')->notEmpty();
+
+/**
+ * @SerDe\AvroType("record")
+ * @SerDe\AvroName("user")
+ */
+class WriterUser
+{
+    /**
+     * @SerDe\AvroType("string")
+     * @var string
+     */
+    private $firstName;
+
+    /**
+     * @SerDe\AvroType("string")
+     * @var string
+     */
+    private $lastName;
+
+    /**
+     * @SerDe\AvroType("int")
+     * @var int
+     */
+    private $age;
+
+    public function __construct(string $firstName, string $lastName, int $age)
+    {
+        $this->firstName = $firstName;
+        $this->lastName = $lastName;
+        $this->age = $age;
+    }
+
+    public function getFirstName(): string
+    {
+        return $this->firstName;
+    }
+
+    public function getLastName(): string
+    {
+        return $this->lastName;
+    }
+
+    public function getAge(): int
+    {
+        return $this->age;
+    }
+}
+
+/**
+ * @SerDe\AvroType("record")
+ * @SerDe\AvroName("user")
+ */
+class ReaderUser
+{
+    /**
+     * @SerDe\AvroType("string")
+     * @var string
+     */
+    private $firstName;
+
+    /**
+     * @SerDe\AvroType("int")
+     * @var int
+     */
+    private $age;
+
+    public function __construct(string $firstName, int $age)
+    {
+        $this->firstName = $firstName;
+        $this->age = $age;
+    }
+
+    public function getFirstName(): string
+    {
+        return $this->firstName;
+    }
+
+    public function getAge(): int
+    {
+        return $this->age;
+    }
+}
+
+$recordSerializer = DefaultRecordSerializerFactory::get(getenv('SCHEMA_REGISTRY_HOST'));
+$schemaGenerator = DefaultSchemaGeneratorFactory::get();
+
+$user = new WriterUser('Francisco', 'Rodrigues', 42);
+
+echo "User object to be serialized:\n";
+echo \var_export($user, true) . "\n\n";
+
+$normalizer = new PropertyNormalizer();
+$encoder = new AvroSerDeEncoder($recordSerializer);
+
+$symfonySerializer = new Serializer([$normalizer], [$encoder]);
+
+$serialized = $symfonySerializer->serialize(
+    $user,
+    AvroSerDeEncoder::FORMAT_AVRO,
+    [
+        AvroSerDeEncoder::CONTEXT_ENCODE_SUBJECT => 'users-value',
+        AvroSerDeEncoder::CONTEXT_ENCODE_WRITERS_SCHEMA => $schemaGenerator->generate(WriterUser::class)->parse(),
+    ]
+);
+
+echo "Confluent Avro wire format serialized binary as hex:\n";
+echo bin2hex($serialized) . "\n\n";
+
+/** @var ReaderUser $deserializedUser */
+$deserializedUser = $symfonySerializer->deserialize($serialized, ReaderUser::class, AvroSerDeEncoder::FORMAT_AVRO, [
+    AvroSerDeEncoder::CONTEXT_DECODE_READERS_SCHEMA => $schemaGenerator->generate(ReaderUser::class)->parse(),
+]);
+
+echo "Deserialized User:\n";
+echo \var_export($deserializedUser, true) . "\n";
+
+Assert::assertEquals(
+    $user->getFirstName(),
+    $deserializedUser->getFirstName()
+);
+
+Assert::assertEquals(
+    $user->getAge(),
+    $deserializedUser->getAge()
+);

src/Objects/DefaultSchemaGeneratorFactory.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace FlixTech\AvroSerializer\Objects;
+
+use Doctrine\Common\Annotations\AnnotationReader;
+use Doctrine\Common\Annotations\AnnotationRegistry;
+use FlixTech\AvroSerializer\Objects\Schema\Generation\SchemaGenerator;
+
+class DefaultSchemaGeneratorFactory
+{
+    public static function get(): SchemaGenerator
+    {
+        AnnotationRegistry::registerLoader('class_exists');
+
+        return new Schema\Generation\SchemaGenerator(
+            new Schema\Generation\AnnotationReader(
+                new AnnotationReader()
+            )
+        );
+    }
+}

src/Objects/Schema/ArrayType.php

@@ -10,19 +10,19 @@ class ArrayType extends ComplexType
 {
     public function __construct()
     {
-        parent::__construct('array');
+        parent::__construct(TypeName::ARRAY);
     }
 
     public function items(Schema $schema): self
     {
-        return $this->attribute('items', $schema);
+        return $this->attribute(AttributeName::ITEMS, $schema);
     }
 
     /**
      * @param array<mixed> $default
      */
     public function default(array $default): self
     {
-        return $this->attribute('default', $default);
+        return $this->attribute(AttributeName::DEFAULT, $default);
     }
 }

src/Objects/Schema/AttributeName.php

@@ -0,0 +1,23 @@
+<?php
+
+declare(strict_types=1);
+
+namespace FlixTech\AvroSerializer\Objects\Schema;
+
+class AttributeName
+{
+    public const ALIASES = 'aliases';
+    public const DEFAULT = 'default';
+    public const DOC = 'doc';
+    public const ITEMS = 'items';
+    public const NAME = 'name';
+    public const NAMESPACE = 'namespace';
+    public const ORDER = 'order';
+    public const SIZE = 'size';
+    public const SYMBOLS = 'symbols';
+    public const TARGET_CLASS = 'targetClass';
+    public const TYPE = 'type';
+    public const VALUES = 'values';
+    public const LOGICAL_TYPE = 'logicalType';
+    public const FIELDS = 'fields';
+}

src/Objects/Schema/BooleanType.php

@@ -8,6 +8,6 @@ class BooleanType extends PrimitiveType
 {
     public function __construct()
     {
-        parent::__construct('boolean');
+        parent::__construct(TypeName::BOOLEAN);
     }
 }

src/Objects/Schema/BytesType.php

@@ -8,6 +8,6 @@ class BytesType extends PrimitiveType
 {
     public function __construct()
     {
-        parent::__construct('bytes');
+        parent::__construct(TypeName::BYTES);
     }
 }

src/Objects/Schema/DateType.php

@@ -4,15 +4,13 @@
 
 namespace FlixTech\AvroSerializer\Objects\Schema;
 
-use FlixTech\AvroSerializer\Objects\Schema;
-
 class DateType extends LogicalType
 {
     public function __construct()
     {
         parent::__construct(
-            'date',
-            Schema::int()->serialize()
+            TypeName::DATE,
+            TypeName::INT
         );
     }
 }

src/Objects/Schema/DoubleType.php

@@ -8,6 +8,6 @@ class DoubleType extends PrimitiveType
 {
     public function __construct()
     {
-        parent::__construct('double');
+        parent::__construct(TypeName::DOUBLE);
     }
 }