Fix: Circular reference detected error (#332)

* Rename function name

* Add uuid handler on json dumps

* Add myself to authors

AUTHORS

@@ -34,3 +34,4 @@ Patches and Suggestions
 - Mathias Loesch
 - Tushar Makkar
 - Andrii Soldatenko
+- Bruno Soares

tablib/formats/_json.py

@@ -3,6 +3,7 @@
 """ Tablib - JSON Support
 """
 import decimal
+from uuid import UUID
 
 import tablib
 
@@ -15,24 +16,23 @@ title = 'json'
 extensions = ('json', 'jsn')
 
 
-def date_handler(obj):
-    if isinstance(obj, decimal.Decimal):
+def serialize_objects_handler(obj):
+    if isinstance(obj, decimal.Decimal) or isinstance(obj, UUID):
         return str(obj)
     elif hasattr(obj, 'isoformat'):
         return obj.isoformat()
     else:
         return obj
-    # return obj.isoformat() if hasattr(obj, 'isoformat') else obj
 
 
 def export_set(dataset):
     """Returns JSON representation of Dataset."""
-    return json.dumps(dataset.dict, default=date_handler)
+    return json.dumps(dataset.dict, default=serialize_objects_handler)
 
 
 def export_book(databook):
     """Returns JSON representation of Databook."""
-    return json.dumps(databook._package(), default=date_handler)
+    return json.dumps(databook._package(), default=serialize_objects_handler)
 
 
 def import_set(dset, in_stream):

test_tablib.py

@@ -6,6 +6,7 @@ import doctest
 import json
 import unittest
 import sys
+from uuid import uuid4
 
 import datetime
 
@@ -226,6 +227,22 @@ class TablibTestCase(unittest.TestCase):
 
         # Delete from invalid index
         self.assertRaises(IndexError, self.founders.__delitem__, 3)
+            
+    def test_json_export(self):
+        """Verify exporting dataset object as JSON"""
+        
+        address_id = uuid4()
+        headers = self.headers + ('address_id',)
+        founders = tablib.Dataset(headers=headers, title='Founders')
+        founders.append(('John', 'Adams', 90, address_id))
+        founders_json = founders.export('json')
+        
+        expected_json = (
+            '[{"first_name": "John", "last_name": "Adams", "gpa": 90, '
+            '"address_id": "%s"}]' % str(address_id)
+        )
+        
+        self.assertEqual(founders_json, expected_json)
 
     def test_csv_export(self):
         """Verify exporting dataset object as CSV."""