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Shaper

Shaper是一个简单的库，它允许进行类型安全的数据转换。您可以进行简单的转换或队列转换。

单向转换

单向转换在数据只单向流动时很有用。一个例子是只读HTTP API，基于输出中的一个属性内容，会向外部服务发送请求，以在原始响应中包含额外数据。

简单转换

以类型安全的方式执行单一操作来转换数据。

use JsonSchema\Validator;
use Shaper\Transformation\TransformationBase;
use Shaper\Util\Context;
use Shaper\Validator\JsonSchemaValidator;


class NumberToArray extends TransformationBase {
  public function getInputValidator() {
    return new JsonSchemaValidator(['type' => 'number'], new Validator());
  }
  public function getOutputValidator() {
    $schema = ['type' => 'array', 'items' => ['type' => 'number']];
    return new JsonSchemaValidator($schema, new Validator());
  }
  protected function doTransform($data, Context $context) {
    return [$context['keyName'] => $data];
  }
}

$t = new NumberToArray();
$t->transform(42, new Context(['keyName' => 'data'])); // ['data' => 42]
$t->transform(['foo']); // TypeError exception.

队列转换

以类型安全的方式执行一系列操作，一个接一个。

use JsonSchema\Validator;
use Shaper\Transformation\TransformationBase;
use Shaper\Util\Context;
use Shaper\Validator\InstanceofValidator;
use Shaper\Validator\JsonSchemaValidator;
use Shaper\Transformation\TransformationsQueue;

class ObjectToNumber extends TransformationBase {
  public function getInputValidator() {
    return new InstanceofValidator(\stdClass::class);
  }
  public function getOutputValidator() {
    $schema = ['type' => 'number'];
    return new JsonSchemaValidator($schema, new Validator());
  }
  protected function doTransform($data, Context $context) {
    return isset($data->value) ? $data->value : 0;
  }
}

$t = new TransformationsQueue();
$t->add(new ObjectToNumber());
$t->add(new NumberToArray());
$input = new \stdClass();
$input->value = 42;
$t->transform($input, new Context(['keyName' => 'data'])); // ['data' => 42]

双向转换（又称数据适配器）

数据适配器或可逆转换在数据可以双向流动时很有用。一个例子是公开内部存储的HTTP API。但是，内部存储的格式不是API想要公开的格式。为此，进入的数据需要转换为内部存储格式，而输出的数据需要转换为通过API公开的形状。

use JsonSchema\Validator;
use Shaper\DataAdaptor\DataAdaptorBase;
use Shaper\Util\Context;
use Shaper\Validator\InstanceofValidator;
use Shaper\Validator\JsonSchemaValidator;

class MyDataAdaptor extends DataAdaptorBase {
  protected function doTransform($data, Context $context) {
    return $data->{$context['keyName']};
  }
  protected function doUndoTransform($data, Context $context) {
    return (object) [$context['keyName'] => $data, 'bar' => 'default'];
  }
  public function getInputValidator() {
    // In a real world scenario we would describe this as a JSON Schema.
    return new InstanceofValidator(\stdClass::class);
  }
  public function getInternalValidator() {
    // In a real world this would be your internal data object. Something like cheking that this is
    // an object of class FieldItemInstance.
    return new JsonSchemaValidator(['type' => 'string'], new Validator());
  }
  public function getOutputValidator() {
    // In a real world scenario we would describe this as a JSON Schema. In most cases the output
    // validator is the same as the input validator, so you can return the input validator here.
    return new InstanceofValidator(\stdClass::class);
  }
}

$da = new MyDataAdaptor();
$data = new \stdClass();
$data->lorem = 'caramba!';
$da->transform($data, new Context(['keyName' => 'lorem'])); // 'caramba!'
$da->transform(new NodeObject()); // TypeError exception.
$da->undoTransform('caramba!', new Context(['keyName' => 'lorem'])); // (object) ['lorem' => 'caramba!', 'bar' => 'default']
$da->undoTransform([]); // TypeError exception.

类图