Thanks for your reply.
I put this in my function.php but it doesn’t work
add_filter('acf/validate_value/key=field_5ab2ca68fcf2b', 'my_acf_validate_value', 10, 4);
function my_acf_validate_value( $valid, $value, $field, $input ){
echo "erreur";
if( !$valid ) {
return $valid;
}
$string = urldecode(get_field("url"));
$parse = parse_url($string);
echo $parse['host'];
if ($parse['host'] != "www.amazon.fr") {
$valid = 'Erreur';
}
return $valid;
}