Always save CharFields and TextFields as empty strings instead of nulls

Fixes dj-stripe#713
Touches dj-stripe#468

djstripe/models/base.py

@@ -176,10 +176,16 @@ def _stripe_object_to_record(cls, data):
                 # TODO (#681): Handle foreign keys automatically
                 # For now they're handled in hooks.
                 continue
+
             if hasattr(field, "stripe_to_db"):
-                result[field.name] = field.stripe_to_db(manipulated_data)
+                field_data = field.stripe_to_db(manipulated_data)
             else:
-                result[field.name] = manipulated_data.get(field.name)
+                field_data = manipulated_data.get(field.name)
+
+            if isinstance(field, (models.CharField, models.TextField)) and field_data is None:
+                field_data = ""
+
+            result[field.name] = field_data
 
         return result
 

tests/__init__.py

@@ -1171,8 +1171,8 @@ def pay(self):
     "email": "[email protected]",
     "payouts_enabled": True,
     "statement_descriptor": "DJSTRIPE",
-    "support_email": "djstripe@exmaple.com",
-    "support_phone": "",
+    "support_email": "djstripe@example.com",
+    "support_phone": None,
     "support_url": "https://example.com/support/",
     "timezone": "Etc/UTC",
     "type": "standard",