DocuSignException in post_recipient_view when recipient's name change is not reflected in database

[smcoll]

Narrowing in on a non-callback issue mentioned in peopledoc/django-docusign#65...

If a user has changed their name using the DocuSign interface while signing, and that name change is not reflected in the database, pydocusignEnvelope.post_recipient_view will raise an exception via DocuSignClient.post_recipient_view:

DocuSignException: DocuSign request failed: POST https://na2.docusign.net/restapi/v2/accounts/<account-id>/envelopes/<envelope_id>/views/recipient returned code 400 while expecting code 201; Message: {  
  "errorCode": "UNKNOWN_ENVELOPE_RECIPIENT",  
  "message": "The recipient you have identified is not a valid recipient of the specified envelope."  
} ;

This is because the lookup includes a name that no longer matches the recipient name in DocuSign's database.

According to https://www.docusign.com/p/RESTAPIGuide/RESTAPIGuide.htm#REST%20API%20References/Post%20Recipient%20View.htm, clientUserId can be used in conjuction with userId in lieu of email+userName to do the lookup. In our case, userName is out of sync with DocuSign, but clientUserId+userId would work.

My proposal is to only use email and userName in the POST data if clientUserIduserId is unavailable. This would prevent the exception in the case of an out-of-sync name where the more reliable clientUserIduserId can be used instead.

To do this, we would need to only pass the defined keyword arguments to DocuSignClient.post_recipient_view in the POST data, and determine which keyword arguments to use in the method call in pydocusignEnvelope.post_recipient_view.

[zebuline]

@smcoll thank you for the ticket; it is very clear and seems to be legit.
Unfortunately I have no time this month for working on pydocusign. If you want to propose a PR, you are more than welcome.