Bulk Update API - control insert vs update

[Anonymous]

I have a question about the Import Lead API:

Import Lead » Marketo Developers

1) Is there any way to control Insert vs Update?   The create lead api has an "action" parameter that can be:

• createOnly
• updateOnly
• createOrUpdate(default request)
• createDuplicate
  

2) If I am doing a bulk update and it updates an existing lead, it seems that fields that are NOT in the uploaded CSV get nulled out.  

For example, assume that there is a lead in Marketo with address and phone field that have values.  Then I bulk upload a CSV file that only has

the address info.  The leads address gets updated, but the phone gets nulled out.  I'd like a way to leave the existing fields in Marekto unchanged if

the lead exists but they have data in fields that are not in the CSV file I am uploading.

[Anonymous]

Actually,  I see now that I was including the col names with empty values.  So by not sending over that col, it will not override the record in Marketo.
So #2 above is not an issue

[John_M]

Well, for (1) It's an upsert, so if the email exists it will update, if not it will insert. for (2) you can protect those fields with "block field updates".. would that work for you?