optional join separator for error messages on colander.Invalid:asdict, if not supplied return list of string instead of single string.

colander/__init__.py

@@ -179,13 +179,15 @@ class Invalid(Exception):
             return str(self.pos)
         return str(self.node.name)
 
-    def asdict(self, translate=None):
+    def asdict(self, translate=None, separator='; '):
         """ Return a dictionary containing a basic
         (non-language-translated) error report for this exception.
 
         If ``translate`` is supplied, it must be a callable taking a
         translation string as its sole argument and returning a localized,
         interpolated string.
+
+        If ``separator`` is supplied, error messages are joined with that.
         """
         paths = self.paths()
         errors = {}
@@ -198,7 +200,12 @@ class Invalid(Exception):
                 keyname and keyparts.append(keyname)
             if translate:
                 msgs = [translate(msg) for msg in msgs]
-            errors['.'.join(keyparts)] = '; '.join(interpolate(msgs))
+            msgs = interpolate(msgs)
+            if separator:
+                msgs = separator.join(msgs)
+            else:
+                msgs = list(msgs)
+            errors['.'.join(keyparts)] = msgs
         return errors
 
     def __str__(self):

colander/tests/test_colander.py

@@ -136,6 +136,14 @@ class TestInvalid(unittest.TestCase):
                 result,
                 {'': ("Number 1 must be lower than number 2; "
                       "They can't be the same, either")})
+        try:
+            schema.deserialize(dict(number1=2, number2=2))
+        except c.Invalid as e:
+            result = e.asdict(separator=None)
+            self.assertEqual(
+                result,
+                {'': ["Number 1 must be lower than number 2",
+                      "They can't be the same, either"]})
 
     def test___str__(self):
         from colander import Positional