如何将alt属性放入循环中的img cmb2中？

如何解决如何将alt属性放入循环中的img cmb2中？

这是我在stackoverflow中的第一个问题。我尝试了多种方法来放置alt属性，但我做不到。这是我的海关代码（CMB2）

add_action( 'cmb2_admin_init','edc_campos_homepage' );
function edc_campos_homepage() {
    $prefix = 'edc_home_page_';
    $id_home = get_option('page_on_front');
    $edc_campos_homepage = new_cmb2_Box( array(
        'id'           => $prefix . 'homepage','title'        => esc_html__( 'Campos de la pagina de Inicio','cmb2' ),'object_types' => array( 'page' ),// Post type
        'context'      => 'normal','priority'     => 'high','show_names'   => true,// Show field names on the left
        'show_on'      => array(
            'id' => array( $id_home ),),// Specific post IDs to display this MetaBox
    ) );
    $edc_campos_homepage->add_field( array(
        'name'         => esc_html__( 'Países participantes','desc'         => esc_html__( 'Cargue las banderas aquí','id'           => $prefix . 'banderas','type'         => 'file_list','preview_size' => array( 100,100 ),// Default: array( 50,50 )
    ) );
}

这是我的循环代码

 <div id="contenedorPaises" class="owl-carousel owl-theme owl-loaded owl-drag">
    <?PHP 
    $banderas = get_post_meta(get_the_ID(),'edc_home_page_banderas',true );
    foreach($banderas as $id=> $bandera){ ?>
      <div class="item">
        <div class="product-wrapper">
          <?PHP 
            $bandera = wp_get_attachment_image_url($id,'full');
            $image_alt = get_post_meta($bandera,'_wp_attachment_image_alt',true);
           ?>
            <img src="<?PHP echo $bandera ?>" class="img-fluid" alt="<?PHP echo $image_alt ?>">
        </div>
      </div>
    <?PHP }?>
  </div>

这是源页面

<div class="owl-item" style="width: 316.6px;">
  <div class="item">
   <div class="product-wrapper">
    <img src="http://domainName/wp-content/uploads/2020/09/el-salvador.png" class="img-fluid" alt="">
      </div>
    </div>
  </div>

这是源页面（参见图片）

Image description