How do I replace a render_callback function for a block?

Question

I like to basically use a modified version of the below function.

There is pre_render_block and other filters. I have not found out how to get attributes and context the exact way that function does.

https://github.com/WordPress/wordpress-develop/blob/5.9/src/wp-includes/blocks.php

I see how I can filter the context there how the file adds the global $post->ID to the block context, but I do not get what filter I am supposed to use to get whatever is in context. The GB functions needs $block->context['queryId']

Am I supposed to unregister the entire block and register it again with my own callback?

/**
 * Renders the `core/query-pagination-numbers` block on the server.
 *
 * @param array    $attributes Block attributes.
 * @param string   $content    Block default content.
 * @param WP_Block $block      Block instance.
 *
 * @return string Returns the pagination numbers for the Query.
 */
function gutenberg_render_block_core_query_pagination_numbers( $attributes, $content, $block ) {
    $page_key = isset( $block->context['queryId'] ) ? 'query-' . $block->context['queryId'] . '-page' : 'query-page';
    $page     = empty( $_GET[ $page_key ] ) ? 1 : (int) $_GET[ $page_key ];
    $max_page = isset( $block->context['query']['pages'] ) ? (int) $block->context['query']['pages'] : 0;

    // stuff
}

/**
 * Registers the `core/query-pagination-numbers` block on the server.
 */
function gutenberg_register_block_core_query_pagination_numbers() {
    register_block_type_from_metadata(
        __DIR__ . '/query-pagination-numbers',
        array(
            'render_callback' => 'gutenberg_render_block_core_query_pagination_numbers',
        )
    );
}
add_action( 'init', 'gutenberg_register_block_core_query_pagination_numbers', 20 );

My test:

add_filter( 'pre_render_block', __NAMESPACE__ . '\replace_pagination', 10, 3 );

function replace_pagination( $pre_render, $parsed_block, $parent_block  ) {

    if ( 'core/query-pagination-numbers' !== $parsed_block['blockName'] ) {
        return $pre_render;
    }

    dd($parsed_block);

    return $pre_render;
}

dd = Kint debugger output :

No context

// OK, I got it, I can get the context from the $parent_block. Probably specific to this Block as it needs the pagination block as a parent. Still like to know how to just replace the callback.

Answer 1

Try This one on your functions.php or main Plugin file

add_filter('register_block_type_args', function ($settings, $name) {
    if ($name == 'demo/content-with-sidebar') {
        $settings['render_callback'] = 'demo_blocks_content_with_sidebar';
    }
    return $settings;
}, null, 2);

replace your block name with demo/content-with-sidebar here demo is the block name space.

Answer 2

Just for completeness, based on @Ronak's answer, actual working code with WP coding standards and types.:

<?php
namespace Nextgenthemes\Stackshitflow;

add_filter(
    'register_block_type_args',
    __NAMESPACE__ . '\change_render_callback_for_query_pagination_numbers',
    10,
    2
);

function change_render_callback_for_query_pagination_numbers( array $settings, string $name ): array {
    if ( 'core/query-pagination-numbers' === $name ) {
        $settings['render_callback'] = __NAMESPACE__ . '\render_query_pagination_numbers';
    }
    return $settings;
}

function render_query_pagination_numbers( array $attributes, string $content, \WP_Block $block ): string {

    $content = '<h1>HELLO WORLD</h1>';

    return $content;
}