如何在WordPress Automattic AMP插件的amp single.php中添加元字段？

Got it, let's solve this issue. The Automattic AMP plugin uses a template context system that wraps post data into its own object (hence the $this->get() syntax), which is why the standard get_post_meta() call might not work as expected in your amp/single.php template. Here's how to properly inject and access your custom fields:

Step 1: Inject Custom Meta into the AMP Template Context #

First, you need to hook into the plugin's data filter to add your post meta to the context that the AMP template uses. Add this code to your theme's functions.php file:

add_filter( 'amp_post_template_data', 'inject_custom_amp_post_meta', 10, 2 );
function inject_custom_amp_post_meta( $template_data, $post ) {
    // Replace 'field_name' with your actual custom meta key
    $template_data['my_custom_meta'] = get_post_meta( $post->ID, 'field_name', true );
    
    // Add more fields here if needed, e.g.:
    // $template_data['another_custom_field'] = get_post_meta( $post->ID, 'another_field', true );
    
    return $template_data;
}

This filter passes the current post object and the existing template data, allowing you to append your custom meta values to the data the template will use.

Step 2: Access the Custom Meta in Your AMP Template #

Now you can retrieve the custom field in your amp/single.php template using the same $this->get() syntax you're familiar with. For meta tags, you might do something like this:

<?php 
// Get the custom meta value (escape it for security!)
$custom_meta = $this->get( 'my_custom_meta' );

// Only output the meta tag if the field has a value
if ( ! empty( $custom_meta ) ) : ?>
    <meta property="your:custom-meta" content="<?php echo esc_attr( $custom_meta ); ?>">
<?php endif; ?>

Why This Works #

The AMP plugin's template system relies on a centralized data object (accessed via $this) instead of directly using the global $post variable in all cases. By using the amp_post_template_data filter, you're adding your custom meta to that centralized data, making it available via $this->get() in the template.

Alternative: Directly Access the Post Object (If Available) #

In some cases, the global $post object might still be accessible in the AMP template. If you want to test this, you could try:

<?php 
global $post;
$custom_meta = get_post_meta( $post->ID, 'field_name', true );
if ( ! empty( $custom_meta ) ) : ?>
    <meta property="your:custom-meta" content="<?php echo esc_attr( $custom_meta ); ?>">
<?php endif; ?>

However, using the filter method is more reliable because it aligns with the plugin's intended data flow and ensures compatibility with future updates.

内容的提问来源于stack exchange，提问作者Egemen