Create instant search using render_block_context filter.

lib/blocks.php

@@ -509,3 +509,32 @@ function _gutenberg_footnotes_force_filtered_html_on_import_filter( $arg ) {
 add_action( 'init', '_gutenberg_footnotes_kses_init' );
 add_action( 'set_current_user', '_gutenberg_footnotes_kses_init' );
 add_filter( 'force_filtered_html_on_import', '_gutenberg_footnotes_force_filtered_html_on_import_filter', 999 );
+
+
+function gutenberg_block_core_query_add_url_filtering( $context ) {
+
+	// Make sure it only runs for blocks with a queryId
+	if ( empty( $context['queryId'] ) ) {
+		return $context;
+	}
+
+	// Check if the instant search gutenberg experiment is enabled
+	$gutenberg_experiments  = get_option( 'gutenberg-experiments' );
+	$instant_search_enabled = $gutenberg_experiments && array_key_exists( 'gutenberg-search-query-block', $gutenberg_experiments );
+	if ( ! $instant_search_enabled ) {
+		return $context;
+	}
+
+	// Get the search key from the URL
+	$search_key = 'instant-search-' . $context['queryId'];
+	if ( ! isset( $_GET[ $search_key ] ) ) {
+		return $context;
+	}
+
+	// Add the search query to the context, it will be picked up by all the blocks that
+	// use the `query` context like `post-template` or `query-pagination`.
+	$context['query']['search'] = sanitize_text_field( $_GET[ $search_key ] );
+
+	return $context;
+}
+add_filter( 'render_block_context', 'gutenberg_block_core_query_add_url_filtering', 10, 2 );

lib/experiments-page.php

@@ -211,9 +211,16 @@ function gutenberg_initialize_experiments_settings() {
 		)
 	);
 
-	register_setting(
+	add_settings_field(	
+		'gutenberg-search-query-block',
+		__( 'Instant Search and Query Block', 'gutenberg' ),
+		'gutenberg_display_experiment_field',
 		'gutenberg-experiments',
-		'gutenberg-experiments'
+		'gutenberg_experiments_section',
+		array(
+			'label' => __( 'Enable instant search functionality of the Search + Query blocks.', 'gutenberg' ),
+			'id'    => 'gutenberg-search-query-block',
+		)
 	);
 }