Allow special characters &,-,_ for ship name and callsign

src/server/BreCal/validators/validation_base_utils.py

@@ -1,20 +1,19 @@
 import typing
-from string import ascii_letters, digits
+import re
 
 
+_VALID = re.compile(r'^[\w &-]+$') # \w == Unicode letters+digits+underscore
+
 def check_if_string_has_special_characters(text:typing.Optional[str]):
     """
     check, whether there are any characters within the provided string, which are not found in the ascii letters or digits
-        ascii_letters: abcd (...) and ABCD (...)
-        digits: 0123 (...)
 
+    Formerly, this solution was used but was found to be too restrictive:
     Source: https://stackoverflow.com/questions/57062794/is-there-a-way-to-check-if-a-string-contains-special-characters
     User: https://stackoverflow.com/users/10035985/andrej-kesely
     returns bool
     """
-    if text is None:
-        return False
-    return bool(set(text).difference(ascii_letters + digits + ' '))
+    return not _VALID.fullmatch(text) if text else False
 
 
 def check_if_int_is_valid_flag(value, enum_object):