Example Gutenberg block with server-side rendering. Gutenberg edit() block creates interface. Gutenberg saves settings automatically, the PHP function passed as `render_callback` to `register_block_type` is used to create HTML for front-end rendering of block.

serve-side-block.js

const { __ } = wp.i18n;
const { registerBlockType } = wp.blocks;
const el = wp.element.createElement;


registerBlockType( 'hiRoy/serverSide', {
    title: __( 'Server Side Block', 'text-domain' ),
    icon: 'networking',
    category: 'common',
    attributes: {
        images : {
            default: [],
            type:   'array',

        }
    },
    edit({attributes, setAttributes, className, focus, id}) {
        //Put a user interface here.

    },
    save({attributes, className}) {
        //gutenberg will save attributes we can use in server-side callback
       return null;
    },
} );

server-side-block.php

 <?php
 register_block_type('hiRoy/serverSide', array(
            'render_callback' => 'hi_roy_render_callback',
            'attributes' => array(
                'images' => array(
                    'type' => 'array'
                )
            )
        )
    );

    function hi_roy_render_callback( $attributes ){
        $images = $attributes[ 'images' ];
        return '<div><!-- put image gallery here--></div>';
    }

Can you show me how to use the example attribute on the serverside?

 register_block_type('hiRoy/serverSide', array(
        'render_callback' => 'hi_roy_render_callback',
        'attributes' => [
            'name' => [
                'type' => 'string'
            ]
        ],
        'example' => [ // <== THIS ONE
           'attributes' => [
               'name' => 'Thomas'
            ]
        ]
    )
);

How do we call the render_callback inside a php class? It doesn't work the usual way.

You have to specify the class that is responsible for the render

'render_callback' =>[$this, 'render_function']

Hi! This seems to be the exact same question and maybe answer to my question here: "How to use output of php render_callback function in the block editors backend?" https://wordpress.stackexchange.com/questions/363703/gutenberg-how-to-use-output-of-php-render-callback-function-in-the-block-editor Maybe someone can help?

How do we call the render_callback inside a php class? It doesn't work the usual way.

As @timotheemoulin already said, or

'render_callback' => function($atts) {
    return $this->render_function($atts);
}

`// const { __ } = wp.i18n;
const { registerBlockType } = wp.blocks;
const { TextControl }= wp.components;

registerBlockType( 'mygutenberg-block/slide-title', {
title: __( 'Server Side Rendering' ),
icon: 'shield',
category: 'common',
keywords: [
__( 'Server Side Rendering' )
],
attributes: {
innerContent: {
type: 'string',
source: 'text',
}
},
edit( {attributes, setAttributes, className, focus, id} ) {
console.log(attributes);

return (
    <div className={ className }>
               <TextControl 
                    label={ __( 'innerContent', 'recipe' ) } 
                    value={ attributes.innerContent }
                    onChange={ ( new_val ) => {
                        setAttributes({ innerContent: new_val })
                    }} />
    </div>
    );
},
save( {attributes, className} ) {
    return null;
},

} );`

`// function hall_render_inner_content($attributes){

return print_r($attributes);

}

function my_custom_block_register_block(){
register_block_type(
'mygutenberg-block/slide-title',
array(
'render_callback' => 'hall_render_inner_content',
'attributes' => array(
'innerContent' => array(
'type' => 'string',
'default' => 'test',
)
)
)
);
}

add_action( 'init', 'my_custom_block_register_block' );`

but when i update or save the post give this error "Updating failed. The response is not a valid JSON response."
screenshot given bellow

https://prnt.sc/umgmzt

Is there any conditional check we can use to check if we are rendering the element in the Gutenberg editor as opposed to the live site? For example I'm showing a form but I want the button disabled when viewing in Gutenberg, thanks!

@wpexplorer Here's a way to check if a block is being rendered inside the Gutenberg editor.

$in_gutenberg_editor = defined('REST_REQUEST') && REST_REQUEST && !empty($_REQUEST['context']) && $_REQUEST['context']==='edit';

Reference:

• Detecting Gutenberg inside render_callback #8846
• Add ability to detect Gutenberg inside render_callback #23810

@eliot-akira - thanks!

How is it supposed to work without calling wp_enqueue_script? Below is the example how i do it in my custom wordpress theme:

<?php
  // this is probably your functions.php file

  function register_hiroy_serverside_block() {
    $script_path = get_template_directory_uri() . '/path/to/your/block/index.js';
    $asset_file = include( '/path/to/your/block/index.asset.php' );

    wp_enqueue_script(
      'hiroy-server-side',
      $script_path,
      $asset_file['dependencies'],
      $asset_file['version']
    );

    register_block_type('hiRoy/serverSide', array(
            'render_callback' => 'hi_roy_render_callback',
            'attributes' => array(
                'images' => array(
                    'type' => 'array'
                )
            )
        )
    );
  }

  function hiroy_render_callback( $attributes ){
    $images = $attributes[ 'images' ];
    return '<div><!-- put image gallery here--></div>';
  }

  add_action( 'init', 'register_hiroy_serverside_block' );
?>

That is the only way i could've got it working. All the tutorials and articles i found did not help me. I still don't understand how your example above can work at all. I mean it is in fact not registering anything, thus no blocks should appear in UI. Please anyone explain me what is it that i'm missing here. The whole wordpress architecture is driving me mad!

@bizm - This gist isn't intended to explain how to register blocks it's just an example showing how to use the render_callback argument. Now, you don't actually have to use wp_enqueue_script to load your block JS file - you can and probably should be loading the file via your block.json file, see here: https://developer.wordpress.org/block-editor/reference-guides/block-api/block-metadata/ and scroll down to "Editor Script".

@bizm Here is a more up to date example of how to set up a server-side rendered block: https://github.com/imaginarymachines/everything-all-of-the-time/blob/main/blocks/php-block/init.php

Two issues with your snippet that need corrected:

• Use wp_register_script instead of wp_enqueue_script
  • https://github.com/imaginarymachines/everything-all-of-the-time/blob/main/blocks/php-block/init.php#L8
• Pass the handle of the register script to "editor_script" argument of register_block_type(). WordPress will enqueue the script when block is used.
  • https://github.com/imaginarymachines/everything-all-of-the-time/blob/main/blocks/php-block/init.php#L20

add_action('init',function(){
  $block_meta = [
    'name' => 'test/test',
    'title' => 'Test',
    'render_callback' => function($attrs,$content,$block){
      return "TEST";
    }
  ];
  register_block_type($block_meta['name'],$block_meta);
  add_action('enqueue_block_editor_assets',function()use($block_meta){
    $screen = get_current_screen();
    if(!$screen->is_block_editor()) return;
    add_action('admin_print_footer_scripts',function()use($block_meta){
      echo "
       <script>
        var block = {
          edit: function({attributes, setAttributes, className, focus, id}) {
            return "HELLO"
          },
          save: function({attributes, className}) {
            return
          }
        }
        wp.blocks.registerBlockType('{$block_meta['name']}',block)
      </script>
      ";
    });
  });
});

$block_metas = array(
    array(
        'name'  => 'domain/faq',
        'title' => __( 'FAQ', 'domain' ),
        'description' => '',
        'category' => 'text',
        'icon'  => 'star-filled',
        'api_version' => 2
    ),
    array(
        'name'  => 'domain/accordion',
        'title' => __( 'Accordion', 'domain' ),
        'description' => '',
        'category' => 'text',
        'icon'  => 'star-filled',
        'api_version' => 2
    )
);
foreach( $block_metas as $block_meta ) {

    $block_meta['render_callback'] = function ( $block_attributes, $content ) use ( $block_meta ) {
        ob_start();

        $file = ( str_contains( $block_meta['name'], '/' ) ) ? explode( '/', $block_meta['name'] )[1] : $block_meta['name'];

        if ( ob_get_level() ) {
            // https://wordpress.stackexchange.com/questions/4462/passing-variables-through-locate-template
            if ( $filepath = locate_template( "blocks/{$file}/{$file}.php", true, true, array_merge( $_REQUEST, $block_meta, $block_attributes ) ) )
                include_once( $filepath );

            $output = ob_get_contents();
            ob_end_clean();
        }

        return $output;
    };
    register_block_type( $block_meta['name'], $block_meta );

    add_action( 'enqueue_block_editor_assets', function() use ( $block_meta ) {
        add_action( 'admin_print_footer_scripts', function() use ( $block_meta ) {
            echo "
            <script>
                wp.blocks.registerBlockType('{$block_meta['name']}', {
                    edit: function( props ) {
                        return wp.element.createElement(
                            wp.serverSideRender, {
                                block: props.name
                            }
                        );
                    },
                    save: function({attributes, className}) {
                        return null;
                    }
                })
            </script>
            ";
        });
    });
}