Saves post meta in WordPress

save-post-meta.php

<?php
/** add save_post_meta to save_post hook */
add_action( 'save_post', 'save_post_meta', 10, 3 );
/**
 * Saves post meta.
 *
 * @param $post_ID
 * @param WP_Post $post
 * @param $update
 *
 */
function save_post_meta( $post_ID, WP_Post $post, $update ) {

	/** process only if update and not autosave and the nonce is verified */
	if(
		( true === $update )
		&& !( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE )
		&& ( isset( $_REQUEST['_wpnonce'] ) && wp_verify_nonce( $_REQUEST['_wpnonce'], 'update-post_' . $post_ID ) )
	) {

		/** @var array $fields to save */
		$fields = array(
			'_hide_content_widgets' => array(
				'absint'
			)
		);

		/**
		 * @var string $field to save
		 * @var array $sanitizers array of functions to use to sanitize the submitted value
		 */
		foreach ( $fields as $field => $sanitizers ) {

			/** if not submitted - delete post meta and do next field */
			if( !isset( $_POST[ $field ] ) ) {
				delete_post_meta( $post_ID, $field );
				continue;
			}

			/** @var mixed $value submitted */
			$value = $_POST[ $field ];

			/** @var callable $sanitizer */
			foreach ( $sanitizers as $sanitizer ) {
				$value = call_user_func( $sanitizer, $value );
			}

			/** save/delete post meta */
			empty( $value ) ? delete_post_meta( $post_ID, $field ) : update_post_meta( $post_ID, $field, $value );

		}

	}

}

Please note: this function does not save integer zero value (nothing that returns true on empty() check)