Support default-values for ENUMs (#23)

Author: CatoTH

lib/avro/schema.php

@@ -1225,13 +1225,28 @@ public function symbol_index($symbol)
     throw new AvroException(sprintf("Invalid symbol value '%s'", $symbol));
   }
 
+  /**
+   * @return mixed the default value of this field
+   */
+  public function default_value() { return $this->extra_attributes[AvroField::DEFAULT_ATTR] ?? null;  }
+
+  /**
+   * @return boolean true if the field has a default and false otherwise
+   */
+  public function has_default_value() {
+      return array_key_exists(AvroField::DEFAULT_ATTR, $this->extra_attributes) &&
+             $this->extra_attributes[AvroField::DEFAULT_ATTR] !== null;
+  }
+
   /**
    * @return mixed
    */
   public function to_avro()
   {
     $avro = parent::to_avro();
     $avro[AvroSchema::SYMBOLS_ATTR] = $this->symbols;
+    if ($this->has_default_value())
+      $avro[AvroField::DEFAULT_ATTR] = $this->default_value();
     return $avro;
   }
 }

test/SchemaTest.php

@@ -572,6 +572,29 @@ function test_enum_doc()
     $this->assertEquals($schema->doc(), "AB is freaky.");
   }
 
+  function test_enum_default()
+  {
+    $json = '{"type": "enum", "name": "blood_types", "symbols": ["A", "AB", "B", "O"]}';
+    $schema = AvroSchema::parse($json);
+
+    $this->assertEquals(null, $schema->default_value());
+    $this->assertEquals(false, $schema->has_default_value());
+
+
+    $json = '{"type": "enum", "name": "blood_types", "default": "AB", "symbols": ["A", "AB", "B", "O"]}';
+    $schema = AvroSchema::parse($json);
+
+    $this->assertEquals([
+      'type' => 'enum',
+      'name' => 'blood_types',
+      'default' => 'AB',
+      'symbols' => ["A", "AB", "B", "O"],
+    ], $schema->to_avro());
+
+    $this->assertEquals('AB', $schema->default_value());
+    $this->assertEquals(true, $schema->has_default_value());
+  }
+
   function test_logical_type()
   {
     $json = '{ "type": "bytes", "logicalType": "decimal", "precision": 4, "scale": 2 }';