Fix: IS_IN_SET with multiple values (#742)

* Fix: IS_IN_SET with multiple values

strkeys is a map object (a lazy iterator in Python 3, unlike Python 2 where it returned a list).
This means If you try to check membership with **in**, it exhausts the iterator progressively, this leads to very funny errors and sometimes the validator would seem to work correctly depending on the order.

* chore: add tests to make sure IS_IN_SET multiple stays fixed

Author: leonelcamara

pydal/validators.py

@@ -590,7 +590,7 @@ def validate(self, value, record_id=None):
                     raise ValidationError(self.translator(self.error_message))
         else:
             values = [value]
-        strkeys = map(str, valuemap)
+        strkeys = set(map(str, valuemap))
         failures = [x for x in values if not str(x) in strkeys]
         if failures and self.theset:
             raise ValidationError(self.translator(self.error_message))

tests/validators.py

@@ -180,6 +180,9 @@ def test_IS_IN_SET(self):
         self.assertEqual(rtn, ("massimo", "Value not allowed"))
         rtn = IS_IN_SET(["max", "john"], multiple=True)(("max", "john"))
         self.assertEqual(rtn, (("max", "john"), None))
+        # order reversed should still be fine
+        rtn = IS_IN_SET(["max", "john"], multiple=True)(("john", "max"))
+        self.assertEqual(rtn, (("john", "max"), None))
         rtn = IS_IN_SET(["max", "john"], multiple=True)(("bill", "john"))
         self.assertEqual(rtn, (("bill", "john"), "Value not allowed"))
         rtn = IS_IN_SET(("id1", "id2"), ["first label", "second label"])(