How to check if field have value

Hi guys, i am trying to output some user profile fields value in joomla article.
What i need is to build an "if" statement that will output the code only if the field have a value.

What i did so far

1. I am getting the author ID of the article like this

$authorid = $this->item->created_by ? $this->item->created_by : $this->item->author;

2. I am setting-up variables for the fields i need

//Author Extended Profile Info

$author_city = Foundry::user($authorid)->getFieldValue('ADDRESS')->value->city;

$author_state = Foundry::user($authorid)->getFieldValue('ADDRESS')->value->state;

$author_about = Foundry::user($authorid)->getFieldValue('ABOUT');

$user_website = Foundry::user($authorid)->getFieldValue('URL');

3. Now, finally, i am trying to "output" those fields ONLY if the field have value ... but it doesn't work

 <?php if( $author_about ){ ?>

	 <?php echo $author_about;?>

<?php } ?>





<?php if( $user_website ){ ?>

                 <a href="http://<?php echo $user_website; ?>/" rel="nofollow" target="_blank"><?php echo $user_website; ?></a>

<?php } ?>

... and so on

How to build that "if" statement in order to output the field only if it contains value ?

Thanks !