get_post_mime_type() – Function | Developer.WordPress.org

Retrieves the mime type of an attachment based on the ID.

Description

This function can be used with any post type, but it makes more sense with attachments.

Parameters

$postint|WP_Postoptional: Post ID or post object. Defaults to global $post.
Default:null

Return

string|false The mime type on success, false on failure.

Source

 *
 * @param int|WP_Post $post Optional. Post ID or post object. Defaults to global $post.
 * @return string|false The mime type on success, false on failure.
 */
function get_post_mime_type( $post = null ) {
	$post = get_post( $post );

	if ( is_object( $post ) ) {
		return $post->post_mime_type;

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Changelog

Version	Description
2.0.0	Introduced.

User Contributed Notes

Codex 9 years ago

Return an icon image path according to the MIME type of the given post

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).'" />';

WordPress already has a function to get the mime type icon called wp_mime_type_icon
https://developer.wordpress.org/reference/functions/wp_mime_type_icon/

get_post_mime_type( int|WP_Post $post = null ): string|false

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