Upload FILE in wordpress through a Template file (frontend)

<form id="featured_upload" method="post" action="#" enctype="multipart/form-data">
<input type="file" name="my_image_upload" id="my_image_upload"  multiple="false" />
<input type="hidden" name="post_id" id="post_id" value="12" />
<?php wp_nonce_field( 'my_image_upload', 'my_image_upload_nonce' ); ?>
<input id="submit_my_image_upload" name="submit_my_image_upload" type="submit" value="Upload" />
</form>

<?php



// Check that the nonce is valid, and the user can edit this post.
if ( 
isset( $_POST['my_image_upload_nonce'], $_POST['post_id'] ) 
&& wp_verify_nonce( $_POST['my_image_upload_nonce'], 'my_image_upload' )
&& current_user_can( 'edit_post', $_POST['post_id'] )
) {
// The nonce was valid and the user has the capabilities, it is safe to continue.

// These files need to be included as dependencies when on the front end.
require_once( ABSPATH . 'wp-admin/includes/image.php' );
require_once( ABSPATH . 'wp-admin/includes/file.php' );
require_once( ABSPATH . 'wp-admin/includes/media.php' );

// Let WordPress handle the upload.
// Remember, 'my_image_upload' is the name of our file input in our form above.
$attachment_id = media_handle_upload( 'my_image_upload', $_POST['post_id'] );

if ( is_wp_error( $attachment_id ) ) {
// There was an error uploading the image.
} else {
// The image was uploaded successfully!
//update_post_meta($pid,'upload_pdf', $attachment_id);
echo $attachment_id;

}

} else {

// The security check failed, maybe show the user an error.
}
 ?>