检查附件是否是图像

Question

I am trying to display an image or video in the place of woocommerce product featured image based on the attachment type. For this, I am trying to check if the post attachment is an image or a video.

I googled and found that get_post_mime_type() will do that job and with the help of wordpress function reference page here, I added the following code but it is not giving me required output, the switch case is always going to default case and I am unable to check the attachment mime type. Did anyone face this issue earlier?

function get_icon_for_attachment($post_id) {
  $base = get_template_directory_uri() . "/images/icons/";
  $type = get_post_mime_type($post_id);
  switch ($type) {
    case 'image/jpeg':
    case 'image/png':
    case 'image/gif':
      return $base . "image.png"; break;
    case 'video/mpeg':
    case 'video/mp4': 
    case 'video/quicktime':
      return $base . "video.png"; break;
    case 'text/csv':
    case 'text/plain': 
    case 'text/xml':
      return $base . "text.png"; break;
    default:
      return $base . "file.png";
  }
}
// call it like this:
echo '<img src="'.get_icon_for_attachment($my_attachment->ID).'" />';

Answer 1

I didn't use this function. Another approach you can see :

    $file_url = wp_get_attachment_url($attachment_id);
    $file_parts = pathinfo($file_url);
    echo $file_parts['extension'];