John Davidson

Message:

I'm trying to write my own code for populating JSON-LD Schema code (I'd rather not rely on plugins for this).

For Wordpress posts, one of the key schema elements is author data. So I use get_the_author_meta() function to access it.

This works perfectly fine when it fires in the wp_footer action, but comes up empty when firing in wp_head.

I've checked this in the astra theme as well as twentytwentyone theme.

I stole this code just for demonstration purposes, it's twitter OG card and not Schema but its effectively the same. Forgive me but I can't remember what stackoverlow post I found it in.

In functions.php:

function my_twitter_cards() {

    if (is_singular()) {

        global $post;

    $twitter_user = get_the_author_meta('nickname'); #This is the element that works in wp_footer but not in wp_head, all the other fields seem to work.

    $twitter_url = get_permalink();

    $twitter_title = get_the_title();

    $twitter_excerpt = get_the_excerpt();

    $twittercard_image = wp_get_attachment_image_src(get_post_thumbnail_id($post->ID), 'full');

    $twittercard_thumb = $twittercard_image[0];

    if (!$twittercard_thumb) {

        $twittercard_thumb = 'https://www.example.com/default-image.png';

    }

    if ($twitter_user) {

        echo '<meta name="twitter:creator" value="@' . esc_attr($twitter_user) . '" />' . "\n";

    }

    echo '<meta name="twitter:card" value="summary" />' . "\n";

    echo '<meta name="twitter:url" value="' . esc_url($twitter_url) . '" />' . "\n";

    echo '<meta name="twitter:title" value="' . esc_attr($twitter_title) . '" />' . "\n";

    echo '<meta name="twitter:description" value="' . esc_attr($twitter_excerpt) . '" />' . "\n";

    echo '<meta name="twitter:image" value="' . esc_url($twittercard_thumb) . '" />' . "\n";

    echo '<meta name="twitter:site" value="@mhthemes" />' . "\n";

    }

}

add_action('wp_head', 'my_twitter_cards');  #swap this out for wp_footer to see the difference.

My theory was that it couldn't access the loop when called in the header, but that doesn't explain why post-specific data is populating (i.e permalink, title, etc), and not the get_the_author_meta data.

Now I can go with it if I just populate the footer, in this application it would be OK, but some things need to be in the header, so I want to figure out why its not working as expected.

Thank you in advance!

---

My Answer:
The issue you are facing is because the `get_the_author_meta()` function relies on the global `$post` variable, which may not be set when the `wp_head` action is fired. To ensure that the author meta data is available in the `wp_head` action, you can manually set the post object before calling the `get_the_author_meta()` function.

Here's how you can modify your code to set the post object before retrieving the author meta data:

php
function my_twitter_cards() {
if (is_singular()) {
global $post;

// Save the current post object
$original_post = $post;

// Set the post object to the current post
$post = get_queried_object();

$twitter_user = get_the_author_meta('nickname', $post->post_author);
$twitter_url = get_permalink();
$twitter_title = get_the_title();
$twitter_excerpt = get_the_excerpt();
$twittercard_image = wp_get_attachment_image_src(get_post_thumbnail_id($post->ID), 'full');
$twittercard_thumb = $twittercard_image[0];

if (!$twittercard_thumb) {
$twittercard_thumb = 'https://www.example.com/default-image.png';
}

if ($twitter_user) {
echo '' . "\n";
}

echo '' . "\n";
echo '' . "\n";
echo '' . "\n";
echo '' . "\n";
echo '' . "\n";
echo '' . "\n";

// Restore the original post object
$post = $original_post;
}
}
add_action('wp_head', 'my_twitter_cards');


By setting the post object to the current post before calling `get_the_author_meta()`, you should now be able to retrieve the author meta data in the `wp_head` action.