save_post action example

save_post_action_example.php

<?php

add_action( 'save_post', 'tivwp_save_post', 10, 3 );

/**
 * Save the selected template info for the particular post
 * @param int      $post_id
 * @param \WP_Post $post
 * @param bool     $update
 * @wp-hook save_post
 */
function tivwp_save_post( $post_id, \WP_Post $post, $update ) {

	// Verify if this is an auto save routine.
	// If it is then our form has not been submitted, so we don't want to do anything
	if ( defined( 'DOING_AUTOSAVE' ) && DOING_AUTOSAVE ) {
		return;
	}

	if ( ! $update ) {
		return;
	}

	if ( $post->post_type !== 'post' ) { // could be a CPT, for example 'product'
		return;
	}

	// Check permissions
	if ( ! current_user_can( 'edit_post', $post_id ) ) {
		return;
	}
	
	/**
	 * @todo
	 * Check for the post status: published, draft, ...
	 * Maybe we do not need to do anything if it goes to trash?
	 */

	/**
	 * IF THAT WAS A METABOX, WE SHOULD HAVE SOME NONCES (name and action)
	 * Verify this came from the our screen and with proper authorization,
	 * because save_post can be triggered at other times
	 */
	if (
		empty( $_POST[TIVWP_NONCE_METABOX_NAME] )
		or ! wp_verify_nonce( $_POST[TIVWP_NONCE_METABOX_NAME], TIVWP_NONCE_METABOX_ACTION )
	) {
		return;
	}

	// Sanitize user input.
	$somevar       = sanitize_text_field( $_POST['somevar'] );

	// Update the meta field in the database.
	update_post_meta( $post_id, '_somevar', array( 'somevar' => $somevar ) );
}