所以我有很多我想用Symfony序列化程序序列化的类.例如
class Foo
{
public $apple = 1;
public $pear = null;
public function serialize() {
Utils::serialize($this);
}
}
我使用以下serialize()调用序列化：
class Utils {
public static function serialize($object) {
$encoder = new XmlEncoder();
$normalizer = new ObjectNormalizer();
$serializer = new Serializer(array($normalizer),array($encoder));
$str = $serializer->serialize($object,'xml')
}
}
产生的输出给了我：
<apple>1</apple><pear/>
预期的输出应为：
<apple>1</apple>
我查看了Symfony 2.8 doc,并设法通过使用$normalizer-> setIgnoredAttributes(“pear”)找到了一个快速解决方案.
所以改进的序列化静态函数看起来像这样
class Utils {
public static function ignoreNullAttributes($object) {
$ignored_attributes = array();
foreach($object as $member => $value) {
if (is_null($object->$member)) {
array_push($ignored_attributes,$member);
}
}
return $ignored_attributes;
}
public static function serialize($object) {
$encoder = new XmlEncoder();
$normalizer = new ObjectNormalizer();
$normalizer->setIgnoredAttributes(Utils::ignoreNullAttributes($object));
$serializer = new Serializer(array($normalizer),'xml')
}
}
然而,这个解决方案并不满足我,因为我有更复杂的情况,其中不同的Foo可以由同一个类拥有.例如
class Bar
{
public $foo1; // (apple=null; pear=2)
public $foo2; // (apple=2; pear=null)
public function serialize() {
Utils::serialize($this);
}
}
这里我不能使用setIgnoredAttributes方法,因为$foo1和$foo2没有相同的null元素.此外,我不在这里从子类(即Foo)调用serialize方法,因此setIgnoredAttributes为空.
无需编写复杂的内省代码,如何使用Symfony 2.8序列化器默认隐藏null元素？例如,我已经看到它默认启用了JMSSerializer.
解决方案是从ObjectNormalizer类扩展,覆盖normalize()方法并删除那里的所有空值：
use Symfony\Component\Serializer\Normalizer\ObjectNormalizer;
use Symfony\Component\Serializer\Serializer;
use Symfony\Component\Serializer\Encoder\XmlEncoder;
class CustomObjectNormalizer extends ObjectNormalizer
{
public function normalize($object,$format = null,array $context = [])
{
$data = parent::normalize($object,$format,$context);
return array_filter($data,function ($value) {
return null !== $value;
});
}
}
$encoders = array(new XmlEncoder());
$normalizers = array(new CustomObjectNormalizer());
$serializer = new Serializer($normalizers,$encoders);
// ...
如果我们有一个Person like the one of the official documentation的数组：
// ...
$person1 = new Person();
$person1->setName('foo');
$person1->setAge(null);
$person1->setSportsman(false);
$person2 = new Person();
$person2->setName('bar');
$person2->setAge(33);
$person2->setSportsman(null);
$persons = array($person1,$person2);
$xmlContent = $serializer->serialize($persons,'xml');
echo $xmlContent;
结果将是那些非空节点：
<?xml version="1.0"?>
<response>
<item key="0">
<name>foo</name>
<sportsman>0</sportsman>
</item>
<item key="1">
<name>bar</name>
<age>33</age>
</item>
</response>
