Merge pull request #232 from Azure/failsafe_error_deserialization

Author: iscai-msft

README.rst

@@ -20,6 +20,15 @@ To install:
 Release History
 ---------------
 
+2021-01-22 Version 0.6.20
++++++++++++++++++++++++++
+
+**Features**
+
+- Add `failsafe_deserialize` method to the `Deserializer` object. When called, ignores any deserialization errors thrown,
+and returns `None`. Recommended when deserializing error models, as in the case of an incorrect error model, we still want
+to return the `HttpResponseError` to the user (without a `model`), instead of throwing a `DeserializationError`.  #232
+
 2020-09-08 Version 0.6.19
 +++++++++++++++++++++++++
 

msrest/serialization.py

@@ -1486,6 +1486,26 @@ def _classify_target(self, target, data):
             pass  # Target is not a Model, no classify
         return target, target.__class__.__name__
 
+    def failsafe_deserialize(self, target_obj, response_data, content_type=None):
+        """Ignores any errors encountered in deserialization,
+        and falls back to not deserializing the object. Recommended
+        for use in error deserialization, as we want to return the
+        HttpResponseError to users, and not have them deal with
+        a deserialization error.
+
+        :param str target_obj: The target object type to deserialize to.
+        :param str/dict data: The response data to deseralize.
+        :param str content_type: Swagger "produces" if available.
+        """
+        try:
+            return self(target_obj, data, content_type=content_type)
+        except:
+            _LOGGER.warning(
+                "Ran into a deserialization error. Ignoring since this is failsafe deserialization",
+				exc_info=True
+            )
+            return None
+
     @staticmethod
     def _unpack_content(raw_data, content_type=None):
         """Extract the correct structure for deserialization.

msrest/version.py

@@ -25,4 +25,4 @@
 # --------------------------------------------------------------------------
 
 #: version of this package. Use msrest.__version__ instead
-msrest_version = "0.6.19"
+msrest_version = "0.6.20"

tests/test_serialization.py

@@ -2533,6 +2533,19 @@ class TestModel(Model):
         m = TestModel.deserialize({'data': {'id': long_type(1)}})
         assert m.data['id'] == long_type(1)
 
+    def test_failsafe_deserialization(self):
+        class Error(Model):
+
+            def __init__(self, **kwargs):
+                self.status = kwargs.pop("status")
+                self.message = kwargs.pop("message")
+
+        with pytest.raises(DeserializationError):
+            self.d(Error, json.dumps(''), 'text/html')
+
+        deserialized = self.d.failsafe_deserialize(Error, json.dumps(''), 'text/html')
+        assert deserialized is None
+
 class TestModelInstanceEquality(unittest.TestCase):
 
     def test_model_instance_equality(self):