Improve CommercetoolsError parsing (#84)

* Improve CommercetoolsError parsing

It now renders the error details as well for better troubleshooting

* Assure errors is always a list

* Parse error code

* Improved error code parsing

Author: tleguijt

src/commercetools/client.py

@@ -265,7 +265,20 @@ def _process_error(self, response: requests.Response) -> None:
         if not response.content:
             response.raise_for_status()
         obj = schemas.ErrorResponseSchema().loads(response.content)
-        raise CommercetoolsError(obj.message, obj, correlation_id)
+
+        # We'll fetch the 'raw' errors from the response because some of the
+        # attributes are not included in the schemas.
+        # With the raw errors in the CommercetoolsError object we can use that
+        # information later to render more detailed error messages
+        errors_raw = []
+        try:
+            response_json = response.json()
+        except ValueError:
+            pass
+        else:
+            errors_raw = response_json.get("errors", [])
+
+        raise CommercetoolsError(obj.message, errors_raw, obj, correlation_id)
 
     def _read_env_vars(self, config: dict) -> dict:
         if not config.get("project_key"):

src/commercetools/exceptions.py

@@ -8,8 +8,46 @@ class CommercetoolsError(Exception):
     correlation_id: typing.Optional[str]
 
     def __init__(
-        self, message: typing.Any, response: ErrorResponse, correlation_id: str = None
+        self,
+        message: typing.Any,
+        errors: typing.List[dict],
+        response: ErrorResponse,
+        correlation_id: str = None,
     ) -> None:
         super().__init__(message)
         self.response = response
+        self.errors = errors
         self.correlation_id = correlation_id
+
+    def __str__(self):
+        result = super().__str__()
+        if self.details:
+            return f"{result} ({', '.join(self.details)})"
+        return result
+
+    @property
+    def details(self) -> typing.List[str]:
+        return [
+            e["detailedErrorMessage"]
+            for e in self.errors
+            if "detailedErrorMessage" in e
+        ]
+
+    @property
+    def codes(self) -> typing.List[str]:
+        try:
+            return [e.code for e in self.response.errors]
+        except AttributeError:
+            return []
+
+    @property
+    def code(self) -> str:
+        """Convenience property to easily get the error code.
+        
+        Returns the code of the first error, just as
+        'message' is always the message of the first error.
+        """
+        try:
+            return self.codes[0]
+        except KeyError:
+            return ""