I am getting an "Undefined variable: output in" error referencing the line: "$content = $content.$output;" in the function below. Any help would be greatly appreciated.
function ld_advanced_custom_field_in_feed($content) {
if(is_feed()) {
$post_id = get_the_ID();
$rssimage = get_field('daily_image');
if( !empty($rssimage) ):
$imgurl = $rssimage['url'];
$imgalt = $rssimage['alt'];
$imgtitle = $rssimage['title'];
$output = '';
$output .= '<daily_vibe_image><img src="';
$output .= $imgurl;
$output .= '" alt="';
$output .= $imgalt;
$output .= '" title="';
$output .= $imgtitle;
$output .= '</daily_vibe_image>';
endif;
$content = $content.$output;
}
return $content;
}
add_filter('the_content','ld_advanced_custom_field_in_feed');