Source

File: wp-includes/blocks.php

function render_block( $parsed_block ) {
	global $post, $wp_query;

	/**
	 * Allows render_block() to be short-circuited, by returning a non-null value.
	 *
	 * @since 5.1.0
	 *
	 * @param string|null $pre_render   The pre-rendered content. Default null.
	 * @param array       $parsed_block The block being rendered.
	 */
	$pre_render = apply_filters( 'pre_render_block', null, $parsed_block );
	if ( ! is_null( $pre_render ) ) {
		return $pre_render;
	}

	$source_block = $parsed_block;

	/**
	 * Filters the block being rendered in render_block(), before it's processed.
	 *
	 * @since 5.1.0
	 *
	 * @param array $parsed_block The block being rendered.
	 * @param array $source_block An un-modified copy of $parsed_block, as it appeared in the source content.
	 */
	$parsed_block = apply_filters( 'render_block_data', $parsed_block, $source_block );

	$context = array();

	if ( $post instanceof WP_Post ) {
		$context['postId'] = $post->ID;

		/*
		 * The `postType` context is largely unnecessary server-side, since the ID
		 * is usually sufficient on its own. That being said, since a block's
		 * manifest is expected to be shared between the server and the client,
		 * it should be included to consistently fulfill the expectation.
		 */
		$context['postType'] = $post->post_type;
	}

	if ( $wp_query instanceof WP_Query && isset( $wp_query->tax_query->queried_terms['category'] ) ) {
		$context['query'] = array( 'categoryIds' => array() );
		foreach ( $wp_query->tax_query->queried_terms['category']['terms'] as $category_slug_or_id ) {
			$context['query']['categoryIds'][] = 'slug' === $wp_query->tax_query->queried_terms['category']['field'] ? get_cat_ID( $category_slug_or_id ) : $category_slug_or_id;
		}
	}

	/**
	 * Filters the default context provided to a rendered block.
	 *
	 * @since 5.5.0
	 *
	 * @param array $context      Default context.
	 * @param array $parsed_block Block being rendered, filtered by `render_block_data`.
	 */
	$context = apply_filters( 'render_block_context', $context, $parsed_block );

	$block = new WP_Block( $parsed_block, $context );

	return $block->render();
}