Handle SimpleLazyObject in payloads (#297)

* This needs some cleanup, but the basic idea is to handle SimpleLazyObject via a custom JSONEncoder subclass

* Use a function instead of a subclass

* Return a string instead of throwing a TypeError

rollbar/__init__.py

@@ -22,7 +22,8 @@
 import requests
 import six
 
-from rollbar.lib import events, filters, dict_merge, parse_qs, text, transport, urljoin, iteritems
+from rollbar.lib import events, filters, dict_merge, parse_qs, text, transport, urljoin, iteritems, defaultJSONEncode
+
 
 __version__ = '0.14.5'
 __log_name__ = 'rollbar'
@@ -1328,7 +1329,7 @@ def _build_payload(data):
 
 
 def _serialize_payload(payload):
-    return json.dumps(payload)
+    return json.dumps(payload, default=defaultJSONEncode)
 
 
 def _send_payload(payload_str, access_token):

rollbar/lib/__init__.py

@@ -4,6 +4,7 @@
 import os
 import sys
 from array import array
+import json
 
 try:
     # Python 3
@@ -212,3 +213,16 @@ def unencodable_object_label(data):
 def undecodable_object_label(data):
     return '<Undecodable type:(%s) base64:(%s)>' % (type(data).__name__,
                                                     base64.b64encode(data).decode('ascii'))
+
+try:
+    from django.utils.functional import SimpleLazyObject
+except ImportError:
+    SimpleLazyObject = None
+
+
+def defaultJSONEncode(o):
+    if SimpleLazyObject and isinstance(o, SimpleLazyObject):
+        if not o._wrapped:
+            o._setup()
+        return o._wrapped
+    return repr(o) + " is not JSON serializable"