Sometimes, you may wish to check a POST variable and when it is not set then get a default value. The first approach could be:

$var = isset( $_POST[ 'var_post' ] ) ? $_POST[ 'var_post' ] : 'default';


However, you could use a simple function to do that:

/**
 * Check a POST and use  default value when it is not set.
 *
 * @param $id_post POST key
 * @param $default  Optional. Default value when is not set.
 */
function isset_post( $id_post, $default = '' ) {
    return( isset( $_POST[ $id_post] ) ? $_POST[ $id_post] : $default );
}


For example:

$var = isset_post( 'product' );

// or

$var = isset_post( 'product', 'phone' );