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https://github.com/pacnpal/django-anymail.git
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Start factoring out common backend functionality
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medmunds
248
anymail/backends/base.py
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248
anymail/backends/base.py
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import json
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import requests
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from django.core.mail.backends.base import BaseEmailBackend
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from .._version import __version__
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from ..exceptions import AnymailError, AnymailRequestsAPIError, AnymailSerializationError, AnymailImproperlyConfigured
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class AnymailBaseBackend(BaseEmailBackend):
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"""
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Base Anymail email backend
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"""
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def open(self):
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"""
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Open and persist a connection to the ESP's API, and whether
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a new connection was created.
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Callers must ensure they later call close, if (and only if) open
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returns True.
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"""
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# Subclasses should use an instance property to maintain a cached
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# connection, and return True iff they initialize that instance
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# property in _this_ open call. (If the cached connection already
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# exists, just do nothing and return False.)
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#
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# Subclasses should swallow operational errors if self.fail_silently
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# (e.g., network errors), but otherwise can raise any errors.
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#
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# (Returning a bool to indicate whether connection was created is
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# borrowed from django.core.email.backends.SMTPBackend)
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return False
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def close(self):
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"""
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Close the cached connection created by open.
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You must only call close if your code called open and it returned True.
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"""
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# Subclasses should tear down the cached connection and clear
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# the instance property.
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#
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# Subclasses should swallow operational errors if self.fail_silently
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# (e.g., network errors), but otherwise can raise any errors.
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pass
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def send_messages(self, email_messages):
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"""
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Sends one or more EmailMessage objects and returns the number of email
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messages sent.
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"""
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# This API is specified by Django's core BaseEmailBackend
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# (so you can't change it to, e.g., return detailed status).
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# Subclasses shouldn't need to override.
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num_sent = 0
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if not email_messages:
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return num_sent
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created_session = self.open()
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try:
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for message in email_messages:
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try:
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sent = self._send(message)
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except AnymailError:
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if self.fail_silently:
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sent = False
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else:
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raise
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if sent:
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num_sent += 1
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finally:
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if created_session:
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self.close()
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return num_sent
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def _send(self, message):
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"""Sends the EmailMessage message, and returns True if the message was sent.
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This should only be called by the base send_messages loop.
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Implementations must raise exceptions derived from AnymailError for
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anticipated failures that should be suppressed in fail_silently mode.
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"""
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message.anymail_status = None
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esp_response_attr = "%s_response" % self.esp_name.lower() # e.g., message.mandrill_response
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setattr(message, esp_response_attr, None) # until we have a response
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if not message.recipients():
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return False
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payload = self.build_message_payload(message)
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# FUTURE: if pre-send-signal OK...
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response = self.post_to_esp(payload, message)
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parsed_response = self.deserialize_response(response, payload, message)
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setattr(message, esp_response_attr, parsed_response)
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message.anymail_status = self.validate_response(parsed_response, response, payload, message)
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# FUTURE: post-send signal
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return True
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def build_message_payload(self, message):
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"""Return a payload with all message-specific options for ESP send call.
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message is an EmailMessage, possibly with additional Anymail-specific attrs
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Can raise AnymailUnsupportedFeature for unsupported options in message.
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"""
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raise NotImplementedError("%s.%s must implement build_message_payload" %
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(self.__class__.__module__, self.__class__.__name__))
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def post_to_esp(self, payload, message):
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"""Post payload to ESP send API endpoint, and return the raw response.
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payload is the result of build_message_payload
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message is the original EmailMessage
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return should be a raw response
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Can raise AnymailAPIError (or derived exception) for problems posting to the ESP
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"""
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raise NotImplementedError("%s.%s must implement build_message_payload" %
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(self.__class__.__module__, self.__class__.__name__))
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def deserialize_response(self, response, payload, message):
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"""Deserialize a raw ESP response
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Can raise AnymailAPIError (or derived exception) if response is unparsable
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"""
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raise NotImplementedError("%s.%s must implement build_message_payload" %
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(self.__class__.__module__, self.__class__.__name__))
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def validate_response(self, parsed_response, response, payload, message):
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"""Validate parsed_response, raising exceptions for any problems, and return normalized status.
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Extend this to provide your own validation checks.
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Validation exceptions should inherit from anymail.exceptions.AnymailError
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for proper fail_silently behavior.
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If *all* recipients are refused or invalid, should raise AnymailRecipientsRefused
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Returns one of "sent", "queued", "refused", "error" or "multi"
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"""
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raise NotImplementedError("%s.%s must implement validate_response" %
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(self.__class__.__module__, self.__class__.__name__))
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@property
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def esp_name(self):
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"""
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Read-only name of the ESP for this backend.
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(E.g., MailgunBackend will return "Mailgun")
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"""
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return self.__class__.__name__.replace("Backend", "")
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class AnymailRequestsBackend(AnymailBaseBackend):
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"""
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Base Anymail email backend for ESPs that use an HTTP API via requests
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"""
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def __init__(self, api_url, **kwargs):
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"""Init options from Django settings"""
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self.api_url = api_url
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super(AnymailRequestsBackend, self).__init__(**kwargs)
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self.session = None
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def open(self):
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if self.session:
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return False # already exists
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try:
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self.session = requests.Session()
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except requests.RequestException:
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if not self.fail_silently:
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raise
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else:
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self.session.headers["User-Agent"] = "Anymail/%s %s" % (
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__version__, self.session.headers.get("User-Agent", ""))
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return True
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def close(self):
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if self.session is None:
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return
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try:
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self.session.close()
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except requests.RequestException:
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if not self.fail_silently:
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raise
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finally:
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self.session = None
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def _send(self, message):
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if self.session is None:
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class_name = self.__class__.__name__
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raise RuntimeError(
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"Session has not been opened in {class_name}._send. "
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"(This is either an implementation error in {class_name}, "
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"or you are incorrectly calling _send directly.)".format(class_name=class_name))
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return super(AnymailRequestsBackend, self)._send(message)
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def get_api_url(self, payload, message):
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"""Return the correct ESP url for sending payload
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Override this to substitute your own logic for determining API endpoint.
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"""
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return self.api_url
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def serialize_payload(self, payload, message):
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"""Return payload serialized to post data.
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Should raise AnymailSerializationError if payload is not serializable
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"""
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try:
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return json.dumps(payload)
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except TypeError as err:
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# Add some context to the "not JSON serializable" message
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raise AnymailSerializationError(orig_err=err, email_message=message, payload=payload)
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def post_to_esp(self, payload, message):
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"""Post payload to ESP send API endpoint, and return the raw response.
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payload is the result of build_message_payload
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message is the original EmailMessage
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return should be a requests.Response
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Can raise AnymailRequestsAPIError for HTTP errors in the post
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"""
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api_url = self.get_api_url(payload, message)
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post_data = self.serialize_payload(payload, message)
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response = self.session.post(api_url, data=post_data)
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if response.status_code != 200:
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raise AnymailRequestsAPIError(email_message=message, payload=payload, response=response)
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return response
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def deserialize_response(self, response, payload, message):
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"""Return parsed ESP API response
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Can raise AnymailRequestsAPIError if response is unparsable
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"""
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try:
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return response.json()
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except ValueError:
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raise AnymailRequestsAPIError("Invalid JSON in %s API response" % self.esp_name,
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email_message=message, payload=payload, response=response)
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