1

(english is not my language so I'm sorry if I don't explain really good)

My custom plugin get an URL from custom metabox and add it into the header.php My problem is that I can't get $post_id in my wp_head function to insert the URL in the header (all works fine before this).

Add my code from my custom plugin: 

add_action( 'add_meta_boxes', 'extra_metabox' );

function extra_metabox () {

add_meta_box( 'extra-metabox', 'Extra Meta Box', 'extra_create_mb', array('page','post'), 'normal', 'core' );
}

function extra_create_mb( $post ){

wp_nonce_field( 'wpe_extra_nonce_save', 'wpe_extra_nonce' );

$meta_alternate = get_post_meta( $post->ID, 'extra_meta_alternate', true );

$html=
    '<table width="100%">
        <tr>
            <td style="width: 20%" valign="top"><label for="extra_meta_alternate">'.__('Alternate', 'extra_custom_alternate_redirect').'</label></td>
            <td>
                <input type="url" id="extra_meta_alternate" name="extra_meta_alternate" pattern="https://.*" value="' . esc_attr( $meta_alternate ) . '" style="width: 100%;">
            </td>
        </tr>
    </table>';


function extra_save_mb( $post_id ) {

$nonce_name   = isset( $_POST['wpe_extra_nonce'] ) ? $_POST['wpe_extra_nonce'] : '';
$nonce_action = 'wpe_extra_nonce_save';

if ( ! isset( $nonce_name ) ) {
    return;
}

if ( ! wp_verify_nonce( $nonce_name, $nonce_action ) ) {
    return;
}

if ( wp_is_post_revision( $post_id ) ) {
    return;
}

update_post_meta( $post_id, 'extra_meta_alternate', sanitize_text_field($_POST['extra_meta_alternate'] ) );

 }
add_action( 'save_post', 'extra_save_mb' );


function extra_head(){
//global $post;
$meta_alternate = get_post_meta( $post->ID, 'extra_meta_alternate', true );
//$meta_alternate = get_post_meta( $post_id, 'extra_meta_alternate', true );
//$meta_alternate = get_post_meta( get_the_ID(), 'extra_meta_alternate', true );
if ( is_page() || is_single() ){

        echo '<link rel="alternate" media="only screen and (max-width:400px)" href="'.$meta_alternate.'" />';   
        }   
}
add_action ('wp_head', 'extra_head');

But in <head></head> only print: 

<link rel="alternate" media="only screen and (max-width: 400px)" href="">

Also I try to add global $post inside extra_head() or get_the_ID()but didn't work.

I'm relatively new with this, so thanks for the help.

Improve this question
1

1 Answer 1

Reset to default
3

Use get_queried_object_id() to get the post ID of the current page/post when viewing a single page or post, regardless of whether or not you're in the loop, or what the global $post variable happens to be at that moment:

if ( is_page() || is_single() ) {
    $post_id        = get_queried_object_id();
    $meta_alternate = get_post_meta( $post_id, 'extra_meta_alternate', true );

    echo '<link rel="alternate" media="only screen and (max-width:400px)" href="' . $meta_alternate. '" />';   
}

Note that I moved the get_queried_object_id() and get_post_meta() to inside the if statement. This is because if you're not on a page or post, the queried object ID could be the ID of a category or tag. This makes sure you're only getting the ID if you're on a post or page.

Improve this answer
0

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge that you have read and understand our privacy policy and code of conduct.

Not the answer you're looking for? Browse other questions tagged or ask your own question.