How to check if there is data in a field?

Question

WordPress

Good afternoon!
How to check if a field is empty in a function:

<?php echo get_post_meta($post->ID, 'value', true);  ?>

And if not empty, then output it, otherwise not.
Something like:

if isset ($value) {
<p>
<?php echo get_post_meta($post->ID, 'value', true);  ?>
</p>
}

What is it for? So that an empty paragraph or container does not hang out in the code.

Answer 1

I understand that you need to check what the get_post_meta() function returns?
if so, then check
But this will only work when the get_post_meta() function returns NULL or FALSE. If it can return a space, then it's better to check the length of the string.

Answer 2

If the field exists and the value is not empty:

if( ! empty( get_post_meta( $post->ID, 'value', true ) ) ) {
    echo get_post_meta($post->ID, 'value', true);
}

If you need to check for a space (mentioned kernUSR edge case), then you can wrap it in trim:

if( ! empty( trim( get_post_meta( $post->ID, 'value', true ) ) ) ) {
    echo get_post_meta($post->ID, 'value', true);
}

But, IMHO, it's overkill. It is unlikely that you will have fields with spaces, although if it is user generated content, then everything is possible.