Invalid string produced when using FRIENDLY_ID_STRING_LENGTH that is not long enough

[otonoton]

I know this is an old (and probably abandoned) repo, but for others who might have borrowed friendly_id.py from here, I just want to point out a rather nasty bug I found.

If you set FRIENDLY_ID_STRING_LENGTH, and it happens to be set to a number that is too low for the ID number you are encoding, it will silently return an invalid string.

Here is a patch that instead raises an exception if that is the case:

--- a/friendly_id.py 2024-07-22 22:37:03.011344800 -0400
+++ b/friendly_id.py 2026-02-22 17:48:01.970600546 -0500
@@ -99,11 +99,13 @@
     string = ""
     # The length of the string can be determined by STRING_LENGTH or by how many
     # characters are necessary to present a base 30 representation of SIZE.
-    while STRING_LENGTH and len(string) <= STRING_LENGTH \
+    while STRING_LENGTH and len(string) < STRING_LENGTH \
                 or len(VALID_CHARS)**len(string) <= SIZE:
         # PREpend string (to remove all obvious signs of order)
         string = VALID_CHARS[int(num%len(VALID_CHARS))] + string
         num = num/len(VALID_CHARS)
+        if STRING_LENGTH and len(string) > STRING_LENGTH:
+            raise Exception('ID string length not long enough.')
     return string
 
 

Thanks!