Same name in other branches

1. 8.9.x core/modules/big_pipe/src/Render/BigPipe.php \Drupal\big_pipe\Render\BigPipe::sendPlaceholders()
2. 10 core/modules/big_pipe/src/Render/BigPipe.php \Drupal\big_pipe\Render\BigPipe::sendPlaceholders()
3. 11.x core/modules/big_pipe/src/Render/BigPipe.php \Drupal\big_pipe\Render\BigPipe::sendPlaceholders()

Sends BigPipe placeholders' replacements as embedded AJAX responses.

Parameters

array $placeholders: Associative array; the BigPipe placeholders. Keys are the BigPipe placeholder IDs.

array $placeholder_order: Indexed array; the order in which the BigPipe placeholders must be sent. Values are the BigPipe placeholder IDs. (These values correspond to keys in $placeholders.)

\Drupal\Core\Asset\AttachedAssetsInterface $cumulative_assets: The cumulative assets sent so far; to be updated while rendering BigPipe placeholders.

Throws

\Exception If an exception is thrown during the rendering of a placeholder, it is caught to allow the other placeholders to still be replaced. But when error logging is configured to be verbose, the exception is rethrown to simplify debugging.

1 call to BigPipe::sendPlaceholders()

BigPipe::sendContent in core/modules/big_pipe/src/Render/BigPipe.php

Sends an HTML response in chunks using the BigPipe technique.

File

core/modules/big_pipe/src/Render/BigPipe.php, line 520

Class

BigPipe

Service for sending an HTML response in chunks (to get faster page loads).

Namespace

Drupal\big_pipe\Render

Code

protected function sendPlaceholders(array $placeholders, array $placeholder_order, AttachedAssetsInterface $cumulative_assets) {
    // Return early if there are no BigPipe placeholders to send.
    if (empty($placeholders)) {
        return;
    }
    // Send the start signal.
    $this->sendChunk("\n" . static::START_SIGNAL . "\n");
    // A BigPipe response consists of an HTML response plus multiple embedded
    // AJAX responses. To process the attachments of those AJAX responses, we
    // need a fake request that is identical to the main request, but with
    // one change: it must have the right Accept header, otherwise the work-
    // around for a bug in IE9 will cause not JSON, but <textarea>-wrapped JSON
    // to be returned.
    // @see \Drupal\Core\EventSubscriber\AjaxResponseSubscriber::onResponse()
    $fake_request = $this->requestStack
        ->getMainRequest()
        ->duplicate();
    $fake_request->headers
        ->set('Accept', 'application/vnd.drupal-ajax');
    foreach ($placeholder_order as $placeholder_id) {
        if (!isset($placeholders[$placeholder_id])) {
            continue;
        }
        // Render the placeholder.
        $placeholder_render_array = $placeholders[$placeholder_id];
        try {
            $elements = $this->renderPlaceholder($placeholder_id, $placeholder_render_array);
        } catch (\Exception $e) {
            if ($this->configFactory
                ->get('system.logging')
                ->get('error_level') === ERROR_REPORTING_DISPLAY_VERBOSE) {
                throw $e;
            }
            else {
                trigger_error($e, E_USER_ERROR);
                continue;
            }
        }
        // Create a new AjaxResponse.
        $ajax_response = new AjaxResponse();
        // JavaScript's querySelector automatically decodes HTML entities in
        // attributes, so we must decode the entities of the current BigPipe
        // placeholder ID (which has HTML entities encoded since we use it to find
        // the placeholders).
        $big_pipe_js_placeholder_id = Html::decodeEntities($placeholder_id);
        $ajax_response->addCommand(new ReplaceCommand(sprintf('[data-big-pipe-placeholder-id="%s"]', $big_pipe_js_placeholder_id), $elements['#markup']));
        $ajax_response->setAttachments($elements['#attached']);
        // Push a fake request with the asset libraries loaded so far and dispatch
        // KernelEvents::RESPONSE event. This results in the attachments for the
        // AJAX response being processed by AjaxResponseAttachmentsProcessor and
        // hence:
        // - the necessary AJAX commands to load the necessary missing asset
        //   libraries and updated AJAX page state are added to the AJAX response
        // - the attachments associated with the response are finalized, which
        //   allows us to track the total set of asset libraries sent in the
        //   initial HTML response plus all embedded AJAX responses sent so far.
        $fake_request->request
            ->set('ajax_page_state', [
            'libraries' => implode(',', $cumulative_assets->getAlreadyLoadedLibraries()),
        ] + $cumulative_assets->getSettings()['ajaxPageState']);
        try {
            $ajax_response = $this->filterEmbeddedResponse($fake_request, $ajax_response);
        } catch (\Exception $e) {
            if ($this->configFactory
                ->get('system.logging')
                ->get('error_level') === ERROR_REPORTING_DISPLAY_VERBOSE) {
                throw $e;
            }
            else {
                trigger_error($e, E_USER_ERROR);
                continue;
            }
        }
        // Send this embedded AJAX response.
        $json = $ajax_response->getContent();
        $output = <<<EOF
    <script type="application/vnd.drupal-ajax" data-big-pipe-replacement-for-placeholder-with-id="{<span class="php-variable">$placeholder_id</span>}">
    {<span class="php-variable">$json</span>}
    </script>
EOF;
        $this->sendChunk($output);
        // Another placeholder was rendered and sent, track the set of asset
        // libraries sent so far. Any new settings are already sent; we don't need
        // to track those.
        if (isset($ajax_response->getAttachments()['drupalSettings']['ajaxPageState']['libraries'])) {
            $cumulative_assets->setAlreadyLoadedLibraries(explode(',', $ajax_response->getAttachments()['drupalSettings']['ajaxPageState']['libraries']));
        }
    }
    // Send the stop signal.
    $this->sendChunk("\n" . static::STOP_SIGNAL . "\n");
}

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