Fixed metadata serialization of Numbers and DNs

There were following problems:
1. DNs and Decimals weren't properly serialized. Serialization output was object with empty __base64__ attribute. It was fixed by converting them to string.
2. numberical values equal to 0 were excluded from metadata. It broke many of minvalue checks in Web UI. Now excluding only None and False values as initally intended.

https://fedorahosted.org/freeipa/ticket/3052

ipalib/parameters.py

@@ -112,6 +112,7 @@ from errors import ConversionError, RequirementError, ValidationError
 from errors import PasswordMismatch, Base64DecodeError
 from constants import NULLS, TYPE_ERROR, CALLABLE_ERROR
 from text import Gettext, FixMe
+from util import json_serialize
 from ipapython.dn import DN
 
 class DefaultFrom(ReadOnly):
@@ -978,11 +979,11 @@ class Param(ReadOnly):
                 json_dict[a] = [k for k in getattr(self, a, [])]
             else:
                 val = getattr(self, a, '')
-                if val is None or not val:
-                    # ignore false and not set because lack of their presence is
+                if val is None or val is False:
+                    # ignore False and not set because lack of their presence is
                     # the information itself
                     continue;
-                json_dict[a] = val
+                json_dict[a] = json_serialize(val)
         json_dict['class'] = self.__class__.__name__
         json_dict['name'] = self.name
         json_dict['type'] = self.type.__name__

ipalib/plugins/baseldap.py

@@ -628,7 +628,7 @@ class LDAPObject(Object):
     def __json__(self):
         ldap = self.backend
         json_dict = dict(
-            (a, getattr(self, a)) for a in self.json_friendly_attributes
+            (a, json_serialize(getattr(self, a))) for a in self.json_friendly_attributes
         )
         if self.primary_key:
             json_dict['primary_key'] = self.primary_key.name

ipalib/util.py

@@ -26,6 +26,7 @@ import imp
 import time
 import socket
 import re
+import decimal
 from types import NoneType
 from weakref import WeakKeyDictionary
 from dns import resolver, rdatatype
@@ -46,6 +47,8 @@ def json_serialize(obj):
         return obj
     if isinstance(obj, str):
         return obj.decode('utf-8')
+    if isinstance(obj, (decimal.Decimal, DN)):
+        return str(obj)
     if not callable(getattr(obj, '__json__', None)):
         # raise TypeError('%r is not JSON serializable')
         return ''