fixed issue #1409, py2 vs py3

gluon/sqlhtml.py

@@ -54,17 +54,27 @@ REGEX_ALIAS_MATCH = re.compile('^(.*) AS (.*)$')
 def add_class(a, b):
     return a + ' ' + b if a else b
 
+def count_expected_args(f):
+    if hasattr(f,'func_code'):
+        # python 2
+        n = f.func_code.co_argcount - len(f.func_defaults or [])
+        if getattr(f, 'im_self', None):
+            n -= 1
+    elif hasattr(f, '__code__'):
+        # python 3
+        n = f.__code__.co_argcount - len(f.__defaults__ or [])
+        if getattr(f, '__self__', None):
+            n -= 1
+    else:
+        # doh!
+        n = 1
+    return n
 
 def represent(field, value, record):
     f = field.represent
     if not callable(f):
         return str(value)
-    if hasattr(f,'func_code'):
-        n = f.__code__.co_argcount - len(f.__defaults__ or [])
-        if getattr(f, 'im_self', None):
-            n -= 1
-    else:
-        n = 1
+    n = count_expected_args(f)
     if n == 1:
         return f(value)
     elif n == 2: