Error using cc or bcc with recipients substitution_data

[medmunds]

At some point in the past couple of weeks, SparkPost started rejecting the cc recipient in the following call:

from sparkpost import SparkPost
sp = SparkPost()
result = sp.transmissions.send(
    from_email='[email protected]',  # use a valid sender for your account
    recipients=[{
        'address': {'email': '[email protected]'},
        'substitution_data': {'order_no': '12345'}
    }],
    cc=['[email protected]'],
    subject='test',
    text='test merge {{ order_no }}'
)
# {'total_rejected_recipients': 1, 'total_accepted_recipients': 1, 'id': '102374996990914834', 'rcpt_to_errors': [{'message': 'invalid data format/type', 'code': '1300', 'description': 'field \'recipients[1].address.header_to\' value \'{ "substitution_data": { "order_no": "12345" }, "address": { "email": "[email protected]" } }\' is of type \'json_object\', but needs to be of type \'string\''}]}

The problem seems to be in the payload's header_to generated for the cc. If you omit the cc parameter, it works fine. Similarly, if you change to a simple recipients=['[email protected]'], the send is accepted (albeit without the intended substitution data).

This worked (or at least was accepted by the API) on 2016-06-07. I don't believe python-sparkpost has changed during that period. Is this a problem in python-sparkpost, or an intentional API clarification/change? If the latter, is there way to specify substitution_data and cc (or bcc) in the same transmission?

python 3.5 (or 2.7); python-sparkpost 1.2.0

[richleland]

Tested this and it's still an issue. Sample response:

{u'total_accepted_recipients': 1, u'id': u'102478604587741873', u'rcpt_to_errors': [{u'message': u'invalid data format/type', u'code': u'1300', u'description': u'field \'recipients[1].address.header_to\' value \'{ "substitution_data": { "order_no": "12345" }, "address": { "email": "rich.leland+issue118@sparkpos...\' is of type \'json_object\', but needs to be of type \'string\''}], u'total_rejected_recipients': 1}

Looking at that error a json object is being passed to header_to, instead of what is required, a string.

[richleland]

Some further investigation - the issue appears to be in the _format_copies method which results in a payload being sent to SparkPost that looks like this:

{
  "description": null,
  "recipients": [
    {
      "substitution_data": {
        "order_no": "12345"
      },
      "address": {
        "email": "[email protected]"
      }
    },
    {
      "address": {
        "header_to": {
          "substitution_data": {
            "order_no": "12345"
          },
          "address": {
            "email": "[email protected]"
          }
        },
        "email": "[email protected]"
      }
    }
  ],
  "campaign_id": null,
  "return_path": "[email protected]",
  "content": {
    "from": {
      "email": "[email protected]"
    },
    "attachments": [],
    "text": "test merge {{ order_no }}",
    "headers": {
      "CC": "[email protected]"
    },
    "html": null,
    "reply_to": null,
    "use_draft_template": false,
    "template_id": null,
    "subject": "test"
  },
  "substitution_data": null,
  "options": {
    "skip_suppression": null,
    "open_tracking": null,
    "start_time": null,
    "inline_css": null,
    "transactional": null,
    "sandbox": null,
    "click_tracking": null,
    "ip_pool": null
  },
  "metadata": null
}