Добавление мета полей к медиафайлам в WordPress

Для добавление мета-полей к медиафайлам в WordPress понадобится следующий код:

function meta_img_price_edit( $form_fields, $post ) {

   $form_fields['product_price'] = array(
      'label' => 'Цена',
      'input' => 'text',
      'value' => get_post_meta( $post->ID, 'product_price', true ),
   );

//если необходимо добавить не текстовое поле, а, например, radio
$product_izmerenie = get_post_meta( $post->ID, 'product_izmerenie', true );
$checked_s = '';
$checked_m = '';
if($product_izmerenie == 'metr'){
   $checked_m = 'checked';
}
if($product_izmerenie == 'sht'){
   $checked_s = 'checked';
}
$form_fields['product_izmerenie'] = array(
   'label' => 'Единица<br> измерения',
   'input' => 'html',
   'html' => "<input id='izmerenie-sht' $checked_s type='radio' name='attachments[$post->ID][product_izmerenie]' value='sht'><label for='izmerenie-sht'>штука</label><Br>
  <input id='izmerenie-metr' type='radio' $checked_m name='attachments[$post->ID][product_izmerenie]' value='metr'><label for='izmerenie-metr'>метр погонный</label>"
);

return $form_fields;
}

add_filter( 'attachment_fields_to_edit', 'meta_img_price_edit', 10, 2 );

//сохранение значений
function meta_img_price_save( $post, $attachment ) {
if( isset( $attachment['product_price'] ) )
   update_post_meta( $post['ID'], 'product_price', $attachment['product_price'] );
if( isset( $attachment['product_izmerenie'] ) )
   update_post_meta( $post['ID'], 'product_izmerenie', $attachment['product_izmerenie'] );

return $post;
}

add_filter( 'attachment_fields_to_save', 'meta_img_price_save', 10, 2 );

Вывести мета-поля на сайте можно следующим образом:

$price = get_post_meta($post->ID, 'product_price', true);
echo $price;

Например, выведем цену товара в фотогалерее WordPress, для этого изменим вывод галереи:

//изменение вывода галереи
add_filter('post_gallery', 'in_gallery_output', 10, 3);
function in_gallery_output($output, $attr, $instance ) {
    $post = get_post();
    $html5 = current_theme_supports( 'html5', 'gallery' );
    $atts = shortcode_atts( array(
        'order'      => 'ASC',
        'orderby'    => 'menu_order ID',
        'id'         => $post ? $post->ID : 0,
        'itemtag'    => $html5 ? 'figure'     : 'dl',
        'icontag'    => $html5 ? 'div'        : 'dt',
        'captiontag' => $html5 ? 'figcaption' : 'dd',
        'columns'    => 3,
        'size'       => 'thumbnail',
        'include'    => '',
        'exclude'    => '',
        'link'       => ''
    ), $attr, 'gallery' );

    $id = intval( $atts['id'] );

    if ( ! empty( $atts['include'] ) ) {
        $_attachments = get_posts( array( 'include' => $atts['include'], 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => $atts['order'], 'orderby' => $atts['orderby'] ) );

        $attachments = array();
        foreach ( $_attachments as $key => $val ) {
            $attachments[$val->ID] = $_attachments[$key];
        }
    } elseif ( ! empty( $atts['exclude'] ) ) {
        $attachments = get_children( array( 'post_parent' => $id, 'exclude' => $atts['exclude'], 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => $atts['order'], 'orderby' => $atts['orderby'] ) );
    } else {
        $attachments = get_children( array( 'post_parent' => $id, 'post_status' => 'inherit', 'post_type' => 'attachment', 'post_mime_type' => 'image', 'order' => $atts['order'], 'orderby' => $atts['orderby'] ) );
    }

    if ( empty( $attachments ) ) {
        return '';
    }

    if ( is_feed() ) {
        $output = "\n";
        foreach ( $attachments as $att_id => $attachment ) {
            $output .= wp_get_attachment_link( $att_id, $atts['size'], true ) . "\n";
        }
        return $output;
    }

    $itemtag = tag_escape( $atts['itemtag'] );
    $captiontag = tag_escape( $atts['captiontag'] );
    $icontag = tag_escape( $atts['icontag'] );
    $valid_tags = wp_kses_allowed_html( 'post' );
    if ( ! isset( $valid_tags[ $itemtag ] ) ) {
        $itemtag = 'dl';
    }
    if ( ! isset( $valid_tags[ $captiontag ] ) ) {
        $captiontag = 'dd';
    }
    if ( ! isset( $valid_tags[ $icontag ] ) ) {
        $icontag = 'dt';
    }

    $columns = intval( $atts['columns'] );
    $itemwidth = $columns > 0 ? floor(100/$columns) : 100;
    $float = is_rtl() ? 'right' : 'left';

    $selector = "gallery-{$instance}";

    $gallery_style = '';

    /**
     * Filters whether to print default gallery styles.
     *
     * @since 3.1.0
     *
     * @param bool $print Whether to print default gallery styles.
     *                    Defaults to false if the theme supports HTML5 galleries.
     *                    Otherwise, defaults to true.
     */
    if ( apply_filters( 'use_default_gallery_style', ! $html5 ) ) {
        $gallery_style = "
      <style type='text/css'>
         #{$selector} {
            margin: auto;
         }
         #{$selector} .gallery-item {
            float: {$float};
            margin-top: 10px;
            text-align: center;
            width: {$itemwidth}%;
         }
         #{$selector} img {
            border: 2px solid #cfcfcf;
         }
         #{$selector} .gallery-caption {
            margin-left: 0;
         }
         /* see gallery_shortcode() in wp-includes/media.php */
      </style>\n\t\t";
    }

    $size_class = sanitize_html_class( $atts['size'] );
    $gallery_div = "<div id='$selector' class='gallery galleryid-{$id} gallery-columns-{$columns} gallery-size-{$size_class}'>";

    /**
     * Filters the default gallery shortcode CSS styles.
     *
     * @since 2.5.0
     *
     * @param string $gallery_style Default CSS styles and opening HTML div container
     *                              for the gallery shortcode output.
     */
    $output = apply_filters( 'gallery_style', $gallery_style . $gallery_div );

    $i = 0;

    foreach ( $attachments as $id => $attachment ) {

        $attr = ( trim( $attachment->post_excerpt ) ) ? array( 'aria-describedby' => "$selector-$id" ) : '';
        if ( ! empty( $atts['link'] ) && 'file' === $atts['link'] ) {
            $image_output = wp_get_attachment_link( $id, $atts['size'], false, false, false, $attr );
        } elseif ( ! empty( $atts['link'] ) && 'none' === $atts['link'] ) {
            $image_output = wp_get_attachment_image( $id, $atts['size'], false, $attr );
        } else {
            $image_output = wp_get_attachment_link( $id, $atts['size'], true, false, false, $attr );
        }
        $image_meta  = wp_get_attachment_metadata( $id );

        $orientation = '';
        if ( isset( $image_meta['height'], $image_meta['width'] ) ) {
            $orientation = ( $image_meta['height'] > $image_meta['width'] ) ? 'portrait' : 'landscape';
        }
        $output .= "<{$itemtag} class='gallery-item'>";
        $output .= "
         <{$icontag} class='gallery-icon {$orientation}'>
            $image_output
         </{$icontag}>";
            $output .="<b>". wptexturize($attachment->post_title)."</b>" ;
        if ( $captiontag && trim($attachment->post_excerpt) ) {
            $output .= "              
            <{$captiontag} class='wp-caption-text gallery-caption' id='$selector-$id'>
            <div class='gal-desc'>" . wptexturize($attachment->post_excerpt) . "</div>
            </{$captiontag}>";

        }

//добавляем нашу цену
        $price = get_post_meta($id, 'product_price', true);
        if ($price) {
            $output .= "<span class='price-wrapper'>$price р.</span>";
        }
        $output .= "</{$itemtag}>";
        if ( ! $html5 && $columns > 0 && ++$i % $columns == 0 ) {
            $output .= '<br style="clear: both" />';
        }
    }

    if ( ! $html5 && $columns > 0 && $i % $columns !== 0 ) {
        $output .= "
         <br style='clear: both' />";
    }

    $output .= "
      </div>\n";

    return $output;
}