Add send_whatsapp transactional method

README.md

@@ -285,6 +285,36 @@ response = client.send_push(request)
 print(response)
 ```
 
+## WhatsApp
+
+SendWhatsAppRequest requires:
+* `transactional_message_id`: the ID of the transactional WhatsApp message you want to send.
+* an `identifiers` object containing the `id` or `email` of your recipient. If the profile does not exist, Customer.io will create it.
+
+`to` and `_from` are WhatsApp numbers in E.164 format. `_from` (the object field for the `from` payload key, which is a reserved keyword in Python) is optional when the referenced `transactional_message_id` already defines it.
+
+Use `send_whatsapp` referencing your request to send a transactional message. [Learn more about transactional messages and `SendWhatsAppRequest` properties](https://customer.io/docs/journeys/transactional-api).
+
+```python
+from customerio import APIClient, Regions, SendWhatsAppRequest
+client = APIClient("your API key", region=Regions.US)
+
+request = SendWhatsAppRequest(
+  transactional_message_id="3",
+  to="+15551234567",
+  _from="+15559876543",
+  message_data={
+    "name": "person",
+  },
+  identifiers={
+    "id": "2",
+  }
+)
+
+response = client.send_whatsapp(request)
+print(response)
+```
+
 ## Notes
 - The Customer.io Python SDK depends on the [`Requests`](https://pypi.org/project/requests/) library which includes [`urllib3`](https://pypi.org/project/urllib3/) as a transitive dependency.  The [`Requests`](https://pypi.org/project/requests/) library leverages connection pooling defined in [`urllib3`](https://pypi.org/project/urllib3/).  [`urllib3`](https://pypi.org/project/urllib3/) only attempts to retry invocations of `HTTP` methods which are understood to be idempotent (See: [`Retry.DEFAULT_ALLOWED_METHODS`](https://github.com/urllib3/urllib3/blob/main/src/urllib3/util/retry.py#L184)).  Since the `POST` method is not considered to be idempotent, any invocations which require `POST` are not retried.
 

customerio/__init__.py

@@ -5,6 +5,7 @@
     SendInboxMessageRequest,
     SendPushRequest,
     SendSMSRequest,
+    SendWhatsAppRequest,
 )
 from customerio.client_base import CustomerIOException
 from customerio.regions import Regions
@@ -20,4 +21,5 @@
     "SendInboxMessageRequest",
     "SendPushRequest",
     "SendSMSRequest",
+    "SendWhatsAppRequest",
 ]

customerio/api.py

@@ -63,6 +63,14 @@ def _payload_from_fields(source, field_map):
     "send_to_unsubscribed": "send_to_unsubscribed",
 }
 
+WHATSAPP_FIELD_MAP = COMMON_MESSAGE_FIELD_MAP | {
+    # from is a reserved keyword, so the object field is `_from`.
+    "_from": "from",
+    "to": "to",
+    "send_to_unsubscribed": "send_to_unsubscribed",
+    "tracked": "tracked",
+}
+
 INBOX_FIELD_MAP = COMMON_MESSAGE_FIELD_MAP
 IN_APP_FIELD_MAP = COMMON_MESSAGE_FIELD_MAP
 
@@ -108,6 +116,12 @@ def send_sms(self, request):
         resp = self.send_request("POST", self.url + "/v1/send/sms", request)
         return resp.json()
 
+    def send_whatsapp(self, request):
+        if isinstance(request, SendWhatsAppRequest):
+            request = request._to_dict()
+        resp = self.send_request("POST", self.url + "/v1/send/whatsapp", request)
+        return resp.json()
+
     def send_inbox_message(self, request):
         if isinstance(request, SendInboxMessageRequest):
             request = request._to_dict()
@@ -276,6 +290,40 @@ def _to_dict(self):
         return _payload_from_fields(self, SMS_FIELD_MAP)
 
 
+class SendWhatsAppRequest:
+    """An object with all the options available for triggering a transactional WhatsApp message."""
+
+    def __init__(
+        self,
+        transactional_message_id=None,
+        to=None,
+        identifiers=None,
+        _from=None,
+        tracked=None,
+        disable_message_retention=None,
+        send_to_unsubscribed=None,
+        queue_draft=None,
+        message_data=None,
+        send_at=None,
+        language=None,
+    ):
+        self.transactional_message_id = transactional_message_id
+        self.to = to
+        self.identifiers = identifiers
+        self._from = _from
+        self.tracked = tracked
+        self.disable_message_retention = disable_message_retention
+        self.send_to_unsubscribed = send_to_unsubscribed
+        self.queue_draft = queue_draft
+        self.message_data = message_data
+        self.send_at = send_at
+        self.language = language
+
+    def _to_dict(self):
+        """Build a request payload from the object."""
+        return _payload_from_fields(self, WHATSAPP_FIELD_MAP)
+
+
 class SendInboxMessageRequest:
     """An object with all the options available for triggering a transactional inbox message."""
 

tests/test_api.py

@@ -15,6 +15,7 @@
     SendInboxMessageRequest,
     SendPushRequest,
     SendSMSRequest,
+    SendWhatsAppRequest,
 )
 from tests.server import HTTPSTestCase
 
@@ -147,6 +148,36 @@ def test_send_sms(self):
 
         self.client.send_sms(sms)
 
+    def test_send_whatsapp(self):
+        self.client.http.hooks = dict(
+            response=partial(
+                self._check_request,
+                rq={
+                    "method": "POST",
+                    "authorization": "Bearer app_api_key",
+                    "content_type": "application/json",
+                    "url_suffix": "/v1/send/whatsapp",
+                    "body": {
+                        "identifiers": {"id": "customer_1"},
+                        "transactional_message_id": 100,
+                        "to": "+15551234567",
+                        "from": "+15559876543",
+                        "tracked": True,
+                    },
+                },
+            )
+        )
+
+        whatsapp = SendWhatsAppRequest(
+            identifiers={"id": "customer_1"},
+            transactional_message_id=100,
+            to="+15551234567",
+            _from="+15559876543",
+            tracked=True,
+        )
+
+        self.client.send_whatsapp(whatsapp)
+
     def test_send_inbox_message(self):
         self.client.http.hooks = dict(
             response=partial(