<div class="custom-post">
<?php $mid_var = get_post_meta($post->ID, 'فایل',true);
if(isset($mid_var) && !empty($mid_var)) : ?>
<a href="<?php echo get_post_meta($post->ID, 'فایل',true); ?>" class="download-post"> </a>
<?php endif; ?>
<?php $mid_var = get_post_meta($post->ID, 'لینک',true);
if(isset($mid_var) && !empty($mid_var)) : ?>
<a href="<?php echo get_post_meta($post->ID, 'لینک',true); ?>" class="plugin-post"> </a>
<?php endif; ?>
<?php $mid_var = get_post_meta($post->ID, 'نمایش',true);
if(isset($mid_var) && !empty($mid_var)) : ?>
<a href="<?php echo get_post_meta($post->ID, 'نمایش',true); ?>" class="preview-post"> </a>
<?php endif; ?>
</div>