How add post_meta from user_meta?

Question

The plugin search and filter, doesn't retrieve author_meta. So i need to add post_meta from author_meta. Is it possible?

EDIT

I create user_meta in this way:

    function custom_user_profile_fields($user){
    $previous_value = '';
    if( is_object($user) && isset($user->ID) ) {
        $previous_value = get_user_meta( $user->ID, 'company', true );
    }
    ?>
    <h3>Extra profile information</h3>
    <table class="form-table">
        <tr>
            <th><label for="company">Company Name</label></th>
            <td>
                <input type="text" class="regular-text" name="company" value="<?php echo esc_attr( $previous_value ); ?>" id="company" /><br />
                <span class="description">Where are you?</span>
            </td>
        </tr>
    </table>
<?php
}
add_action( 'show_user_profile', 'custom_user_profile_fields' );
add_action( 'edit_user_profile', 'custom_user_profile_fields' );
add_action( "user_new_form", "custom_user_profile_fields" );

function save_custom_user_profile_fields($user_id){

    if(!current_user_can('manage_options'))
        return false;

    # save my custom field
    if( isset($_POST['company']) ) {
        update_user_meta( $user_id, 'company', sanitize_text_field( 
    $_POST['company'] ) );
    } else {
        //Delete the company field if $_POST['company'] is not set
        delete_user_meta( $user_id, 'company', $meta_value );
    }
    }
add_action('user_register', 'save_custom_user_profile_fields');
add_action( 'personal_options_update', 'save_custom_user_profile_fields' );
add_action( 'edit_user_profile_update', 'save_custom_user_profile_fields' );

Now i need to set 'company' as a post_meta.

EDIT

I have added in functions.php your code, and i set every three minutes WP Cron but i didn't found MySql table 'genere' in postmeta. I have changed 'company', now is 'genere', but it's the same.

function  add_cron_recurrence_interval( $schedules ) {
$schedules['every_three_minutes'] = array(
        'interval'  => 180,
        'display'   => __( 'Every 3 Minutes', 'textdomain' )
    );
   return $schedules;
 }
 add_filter( 'cron_schedules', 'add_cron_recurrence_interval' );



 function author_company_post_sync() {
    global $wpdb;
      $posts= $wpdb->get_results("SELECT ID,post_author FROM ".$wpdb-
      >prefix."posts");
    foreach ($posts as $post) {
   $company = get_user_meta($post->post_author, 'genere', true);
 update_user_meta($post->ID, 'genere', $company);
   }
 }

 // schedule with WP Cron to run sync callback once daily...
 if (!wp_next_scheduled('author_company_post_sync')) {
    wp_schedule_event( time(), 'every_three_minutes', 
   'author_company_post_sync');
 }

EDIT

Here the solution: User meta to post

Answer 1

Yo might need the user meta for this

https://codex.wordpress.org/Function_Reference/get_user_meta

You can get to it by including the post author as the user_id.

So:

get_user_meta($post->post_author, 'meta_key'

Answer 2

You might be able to use a filter like this to get the matching author meta field (uses post metakey to check for an author metakey value):

add_filter('get_post_metadata', 'custom_get_author_meta', 10, 4);

function custom_get_author_meta($metadata, $post_id, $meta_key, $single) {
    if (!$metadata) {
        $post = get_post($post_id); 
        $author_id = $post->post_author;
        $value = get_the_author_meta($meta_key, $author_id);
        if ($value) {return $value;}
    }
    return $metadata;
}

Update: Specific answer for edited question:

add_filter('get_post_metadata', 'custom_get_author_company_meta', 10, 4);

function custom_get_author_meta($metadata, $post_id, $meta_key, $single) {
    if (!$meta_key == 'company') {
        $post = get_post($post_id); 
        $author_id = $post->post_author;
        $value = get_user_meta($author_id, 'company', true);
        if ($value) {return $value;}
    }
    return $metadata;
}

That should return the company field from the author's user meta field when you do the following:

$company = get_post_meta($postid, 'company', true);

So also if you are in the loop you can do:

global $post;
$company = get_post_meta($post->ID, 'company', true);

UPDATE: This alternative solution will loop all existing post records and sync the post_meta field 'company' with the author_meta key for the posts author of the same name... daily via WP Cron.

function author_company_post_sync() {
     global $wpdb;
     $posts= $wpdb->get_results("SELECT ID,post_author FROM ".$wpdb->prefix."posts");
     foreach ($posts as $post) {
          $company = get_user_meta($post->post_author, 'company', true);
          update_post_meta($post->ID, 'company', $company);
     }
}

// schedule with WP Cron to run sync callback once daily...
if (!wp_next_scheduled('author_company_post_sync')) {
    wp_schedule_event(time(), 'daily', 'author_company_post_sync');
}

This should make it compatible with any search plugin that wants the post_meta field specified because it will actually exist in that table now also. :-)