Improve Exception handling.

Author: florijanstamenkovic

labelbox/client.py

@@ -75,7 +75,7 @@ def execute(self, query, params=None, timeout=10.0):
             labelbox.exceptions.InvalidQueryError: If `query` is not
                 syntactically or semantically valid (checked server-side).
             labelbox.exceptions.ApiLimitError: If the server API limit was
-                exceeded. See "How to import data" in the online documentation 
+                exceeded. See "How to import data" in the online documentation
                 to see API limits.
             labelbox.exceptions.TimeoutError: If response was not received
                 in `timeout` seconds.
@@ -112,14 +112,14 @@ def convert_value(value):
             raise labelbox.exceptions.NetworkError(e)
 
         except Exception as e:
-            logger.error("Unknown error: %s", str(e))
-            raise labelbox.exceptions.LabelboxError(str(e))
+            raise labelbox.exceptions.LabelboxError(
+                "Unknown error during Client.query(): " + str(e), e)
 
         try:
             response = response.json()
         except:
             raise labelbox.exceptions.LabelboxError(
-                "Failed to parse response as JSON: %s", response.text)
+                "Failed to parse response as JSON: %s" % response.text)
 
         errors = response.get("errors", [])
 
@@ -173,7 +173,7 @@ def check_errors(keywords, *path):
 
     def upload_data(self, data):
         """ Uploads the given data (bytes) to Labelbox.
-        
+
         Args:
             data (bytes): The data to upload.
         Returns:
@@ -199,9 +199,9 @@ def upload_data(self, data):
 
         try:
             file_data = response.json().get("data", None)
-        except ValueError: # response is not valid JSON
+        except ValueError as e: # response is not valid JSON
             raise labelbox.exceptions.LabelboxError(
-                "Failed to upload, unknown cause")
+                "Failed to upload, unknown cause", e)
 
         if not file_data or not file_data.get("uploadFile", None):
             raise labelbox.exceptions.LabelboxError(

labelbox/exceptions.py

@@ -1,8 +1,18 @@
 class LabelboxError(Exception):
     """Base class for exceptions."""
-    def __init__(self, message, *args):
-        super().__init__(*args)
+    def __init__(self, message, cause=None):
+        """
+        Args:
+            message (str): Informative message about the exception.
+            cause (Exception): The cause of the exception (an Exception
+                raised by Python or another library). Optional.
+        """
+        super().__init__(message, cause)
         self.message = message
+        self.cause = cause
+
+    def __str__(self):
+        return self._message + str(self.args)
 
 
 class AuthenticationError(LabelboxError):
@@ -31,9 +41,8 @@ def __init__(self, db_object_type, params):
 
 
 class ValidationFailedError(LabelboxError):
-    """Exception raised for when a GraphQL query fails validation (query cost, etc.)
-
-       E.g. a query that is too expensive, or depth is too deep.
+    """Exception raised for when a GraphQL query fails validation (query cost,
+    etc.) E.g. a query that is too expensive, or depth is too deep.
     """
     pass
 
@@ -47,10 +56,8 @@ class InvalidQueryError(LabelboxError):
 
 class NetworkError(LabelboxError):
     """Raised when an HTTPError occurs."""
-    def __init__(self, cause, message=None):
-        if message is None:
-            message = str(cause)
-        super().__init__(message)
+    def __init__(self, cause):
+        super().__init__(str(cause), cause)
         self.cause = cause