ob_start - PHP code example

PHP Function Ob_Start

The php function ob_start helps to enable the buffering of specific output before any type of echoing or any HTML in your PHP scripts. This helps in increasing the performance of your web application as PHP is an interpreted programming language and each statement is executed one after the other. So PHP tends to send the HTML to the web browsers in chunks which reduces the performance. To overcome this problem PHP programming language introduces the output buffering.

Buffers are stackable, which means you may call ob_start() while another ob_start() is active as long as ob_end_flush() is called before the end of your script. If multiple output callback functions are active, output is filtered sequentially through them in their nesting order. If the ob_end_flush() function is not called, original output is sent to the browser as is.

In the above script, three string values have been sent to the buffer. The callback function convert_upper() is used to change the content of the output buffer into uppercase. The output of ob_get_contents() will be stored into the three variables and when ob_end_flush() will be called, the contents of these variable will be sent to the browser. The var_dump() function is used to dumb the contents of these three variables.

PHP is the OG of programming for the web and WordPress, built in PHP, powers 25% of the internet at large. But it’s not just a little venerable language that’s going away any time soon – the php function ob_start is an extremely powerful tool for anyone who uses PHP to build web applications.

ob_start example

        $this->store->unlock($request);
    }

    /** * Restores the Response body. */
    private function restoreResponseBody(Request $request, Response $response): void
    {
        if ($response->headers->has('X-Body-Eval')) {
            \assert(self::BODY_EVAL_BOUNDARY_LENGTH === 24);

            ob_start();

            $content = $response->getContent();
            $boundary = substr($content, 0, 24);
            $j = strpos($content, $boundary, 24);
            echo substr($content, 24, $j - 24);
            $i = $j + 24;

            while (false !== $j = strpos($content, $boundary, $i)) {
                [$uri, $alt, $ignoreErrors, $part] = explode("\n", substr($content, $i, $j - $i), 4);
                $i = $j + 24;

            }
            if ($this->_specificOptions['debug_header']) {
                echo 'DEBUG HEADER : This is a cached page !';
            }
            echo $data;
            if ($doNotDie) {
                return true;
            }
            die();
        }
        ob_start(array($this, '_flush'));
        ob_implicit_flush(false);
        return false;
    }

    /** * Cancel the current caching process */
    public function cancel()
    {
        $this->_cancel = true;
    }

    public function start_el( &$output, $data_object, $depth = 0, $args = array(), $current_object_id = 0 ) {
        // Restores the more descriptive, specific name for use within this method.         $comment = $data_object;

        $depth++;
        $GLOBALS['comment_depth'] = $depth;
        $GLOBALS['comment']       = $comment;

        if ( ! empty( $args['callback'] ) ) {
            ob_start();
            call_user_func( $args['callback'], $comment, $args, $depth );
            $output .= ob_get_clean();
            return;
        }

        if ( 'comment' === $comment->comment_type ) {
            add_filter( 'comment_text', array( $this, 'filter_comment_text' ), 40, 2 );
        }

        if ( ( 'pingback' === $comment->comment_type || 'trackback' === $comment->comment_type ) && $args['short_ping'] ) {
            ob_start();

$controller->initController($request, $response);

        $controller->setFront($this->Front());

        $action = $this->getActionMethod($request);

        $request->setDispatched(true);

        $disableOb = $this->Front()->getParam('disableOutputBuffering');
        $obLevel = ob_get_level();
        if (empty($disableOb)) {
            ob_start();
        }

        try {
            $controller->dispatch($action);
        } catch (Exception $e) {
            $curObLevel = ob_get_level();
            if ($curObLevel > $obLevel) {
                do {
                    ob_get_clean();
                    $curObLevel = ob_get_level();
                } while ($curObLevel > $obLevel);
            }

$encodedEnvelope = $serializer->encode(new Envelope(new DummyMessage('Hello')));
        // Simulate a change in the code base         $encodedEnvelope['body'] = str_replace('DummyMessage', 'OupsyMessage', $encodedEnvelope['body']);

        $envelope = $serializer->decode($encodedEnvelope);

        $lastMessageDecodingFailedStamp = $envelope->last(MessageDecodingFailedStamp::class);
        $this->assertInstanceOf(MessageDecodingFailedStamp::class, $lastMessageDecodingFailedStamp);
        $message = $envelope->getMessage();
        // The class does not exist, so we cannot use anything else. The only         // purpose of this feature is to aim debugging (so dumping value)         ob_start();
        var_dump($message);
        $content = ob_get_clean();
        // remove object ID         $content = preg_replace('/#\d+/', '', $content);
        $expected = <<<EOT object(__PHP_Incomplete_Class) (2) { ["__PHP_Incomplete_Class_Name"]=> string(55) "Symfony\Component\Messenger\Tests\Fixtures\OupsyMessage" ["message":"Symfony\Component\Messenger\Tests\Fixtures\OupsyMessage":private]=> string(5) "Hello" }

use PHPUnit\Framework\TestCase;
use Symfony\Component\VarDumper\Cloner\VarCloner;
use Symfony\Component\VarDumper\Dumper\CliDumper;
use Symfony\Component\VarDumper\VarDumper;

class FunctionsTest extends TestCase
{
    public function testDumpWithoutArg()
    {
        $this->setupVarDumper();

        ob_start();
        $return = dump();
        ob_end_clean();

        $this->assertNull($return);
    }

    public function testDumpReturnsFirstArg()
    {
        $this->setupVarDumper();

        $var1 = 'a';

    protected function extra_tablenav( $which ) {
        ?> <div class="alignleft actions"> <?php         if ( 'top' === $which ) {
            ob_start();

            /** * Fires before the Filter button on the MS sites list table. * * @since 5.3.0 * * @param string $which The location of the extra table nav markup: 'top' or 'bottom'. */
            do_action( 'restrict_manage_sites', $which );

            $output = ob_get_clean();

KernelEvents::FINISH_REQUEST => [['onKernelFinishRequest', 0]],
            KernelEvents::EXCEPTION => ['onKernelException', -64],
        ];
    }

    private function createWelcomeResponse(): Response
    {
        $version = Kernel::VERSION;
        $projectDir = realpath((string) $this->projectDir).\DIRECTORY_SEPARATOR;
        $docVersion = substr(Kernel::VERSION, 0, 3);

        ob_start();
        include \dirname(__DIR__).'/Resources/welcome.html.php';

        return new Response(ob_get_clean(), Response::HTTP_NOT_FOUND);
    }
}

'delete_widget'   => '1',
            );
            $_REQUEST = $_POST;

            /** This action is documented in wp-admin/widgets-form.php */
            do_action( 'delete_widget', $widget_id, $sidebar_id, $id_base );

            $callback = $wp_registered_widget_updates[ $id_base ]['callback'];
            $params   = $wp_registered_widget_updates[ $id_base ]['params'];

            if ( is_callable( $callback ) ) {
                ob_start();
                call_user_func_array( $callback, $params );
                ob_end_clean();
            }

            $_POST    = $original_post;
            $_REQUEST = $original_request;

            $widget_object = $wp_widget_factory->get_widget_object( $id_base );

            if ( $widget_object ) {
                /* * WP_Widget sets `updated = true` after an update to prevent more than one widget * from being saved per request. This isn't what we want in the REST API, though, * as we support batch requests. */

/** * Returns the output of WP_Widget::widget() when called with the provided * instance. Used by encode_form_data() to preview a widget. * @since 5.8.0 * * @param string $widget The widget's PHP class name (see class-wp-widget.php). * @param array $instance Widget instance settings. * @return string */
    private function get_widget_preview( $widget, $instance ) {
        ob_start();
        the_widget( $widget, $instance );
        return ob_get_clean();
    }

    /** * Returns the output of WP_Widget::form() when called with the provided * instance. Used by encode_form_data() to preview a widget's form. * * @since 5.8.0 * * @param WP_Widget $widget_object Widget object to call widget() on. * @param array $instance Widget instance settings. * @return string */

/** * Displays the PHP info. * * @throws NotFoundHttpException */
    public function phpinfoAction(): Response
    {
        $this->denyAccessIfProfilerDisabled();

        $this->cspHandler?->disableCsp();

        ob_start();
        phpinfo();
        $phpinfo = ob_get_clean();

        return new Response($phpinfo, 200, ['Content-Type' => 'text/html']);
    }

    /** * Displays the Xdebug info. * * @throws NotFoundHttpException */

// If this isn't the legacy block, we need to render the static version of this block.     $is_legacy = 'core/post-comments' === $block->name || ! empty( $attributes['legacy'] );
    if ( ! $is_legacy ) {
        return $block->render( array( 'dynamic' => false ) );
    }

    $post_before = $post;
    $post        = get_post( $post_id );
    setup_postdata( $post );

    ob_start();

    /* * There's a deprecation warning generated by WP Core. * Ideally this deprecation is removed from Core. * In the meantime, this removes it from the output. */
    add_filter( 'deprecated_file_trigger_error', '__return_false' );
    comments_template();
    remove_filter( 'deprecated_file_trigger_error', '__return_false' );

    $output = ob_get_clean();

'</span></button>' : '';
    }

    /** * Handles an incoming ajax request (called from admin-ajax.php) * * @since 3.1.0 */
    public function ajax_response() {
        $this->prepare_items();

        ob_start();
        if ( ! empty( $_REQUEST['no_placeholder'] ) ) {
            $this->display_rows();
        } else {
            $this->display_rows_or_placeholder();
        }

        $rows = ob_get_clean();

        $response = array( 'rows' => $rows );

        if ( isset( $this->_pagination_args['total_items'] ) ) {

<?php esc_html_e( 'Date' ); ?></legend> <div class="day-fields clear"> <?php ob_start(); ?> <label for="{{ idPrefix }}date-time-month" class="screen-reader-text"> <?php                         /* translators: Hidden accessibility text. */
                        esc_html_e( 'Month' );
                        ?> </label> <select id="{{ idPrefix }}date-time-month" class="date-input month" data-component="month"> <# _.each( data.month_choices, function( choice ) { if ( _.isObject( choice ) && ! _.isUndefined( choice.text ) && ! _.isUndefined( choice.value ) ) { text = choice.text; value = choice.value; } #> <option value="{{ value }}" > {{ text }} </option> <# } ); #> </select>