Viewing file:  StreamedJsonResponse.php (5.16 KB) -rw-r--r--
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<?php
/*
* This file is part of the Symfony package.
*
* (c) Fabien Potencier <fabien@symfony.com>
*
* For the full copyright and license information, please view the LICENSE
* file that was distributed with this source code.
*/
namespace Symfony\Component\HttpFoundation;
/**
* StreamedJsonResponse represents a streamed HTTP response for JSON.
*
* A StreamedJsonResponse uses a structure and generics to create an
* efficient resource-saving JSON response.
*
* It is recommended to use flush() function after a specific number of items to directly stream the data.
*
* @see flush()
*
* @author Alexander Schranz <alexander@sulu.io>
*
* Example usage:
*
* function loadArticles(): \Generator
* // some streamed loading
* yield ['title' => 'Article 1'];
* yield ['title' => 'Article 2'];
* yield ['title' => 'Article 3'];
* // recommended to use flush() after every specific number of items
* }),
*
* $response = new StreamedJsonResponse(
* // json structure with generators in which will be streamed
* [
* '_embedded' => [
* 'articles' => loadArticles(), // any generator which you want to stream as list of data
* ],
* ],
* );
*/
class StreamedJsonResponse extends StreamedResponse
{
private const PLACEHOLDER = '__symfony_json__';
/**
* @param mixed[] $data JSON Data containing PHP generators which will be streamed as list of data
* @param int $status The HTTP status code (200 "OK" by default)
* @param array<string, string|string[]> $headers An array of HTTP headers
* @param int $encodingOptions Flags for the json_encode() function
*/
public function __construct(
private readonly array $data,
int $status = 200,
array $headers = [],
private int $encodingOptions = JsonResponse::DEFAULT_ENCODING_OPTIONS,
) {
parent::__construct($this->stream(...), $status, $headers);
if (!$this->headers->get('Content-Type')) {
$this->headers->set('Content-Type', 'application/json');
}
}
private function stream(): void
{
$generators = [];
$structure = $this->data;
array_walk_recursive($structure, function (&$item, $key) use (&$generators) {
if (self::PLACEHOLDER === $key) {
// if the placeholder is already in the structure it should be replaced with a new one that explode
// works like expected for the structure
$generators[] = $key;
}
// generators should be used but for better DX all kind of Traversable and objects are supported
if (\is_object($item)) {
$generators[] = $item;
$item = self::PLACEHOLDER;
} elseif (self::PLACEHOLDER === $item) {
// if the placeholder is already in the structure it should be replaced with a new one that explode
// works like expected for the structure
$generators[] = $item;
}
});
$jsonEncodingOptions = \JSON_THROW_ON_ERROR | $this->encodingOptions;
$keyEncodingOptions = $jsonEncodingOptions & ~\JSON_NUMERIC_CHECK;
$jsonParts = explode('"'.self::PLACEHOLDER.'"', json_encode($structure, $jsonEncodingOptions));
foreach ($generators as $index => $generator) {
// send first and between parts of the structure
echo $jsonParts[$index];
if ($generator instanceof \JsonSerializable || !$generator instanceof \Traversable) {
// the placeholders, JsonSerializable and none traversable items in the structure are rendered here
echo json_encode($generator, $jsonEncodingOptions);
continue;
}
$isFirstItem = true;
$startTag = '[';
foreach ($generator as $key => $item) {
if ($isFirstItem) {
$isFirstItem = false;
// depending on the first elements key the generator is detected as a list or map
// we can not check for a whole list or map because that would hurt the performance
// of the streamed response which is the main goal of this response class
if (0 !== $key) {
$startTag = '{';
}
echo $startTag;
} else {
// if not first element of the generic, a separator is required between the elements
echo ',';
}
if ('{' === $startTag) {
echo json_encode((string) $key, $keyEncodingOptions).':';
}
echo json_encode($item, $jsonEncodingOptions);
}
if ($isFirstItem) { // indicates that the generator was empty
echo '[';
}
echo '[' === $startTag ? ']' : '}';
}
// send last part of the structure
echo $jsonParts[array_key_last($jsonParts)];
}
}
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