First run at 500 error handling in fetch_resource

dspace_rest_client/client.py

@@ -36,6 +36,7 @@
     User,
     Group,
     DSpaceObject,
+    DSpaceServerError
 )
 from . import __version__
 
@@ -594,7 +595,19 @@ def fetch_resource(self, url, params=None):
         r = self.api_get(url, params, None)
         if r.status_code != 200:
             logging.error("Error encountered fetching resource: %s", r.text)
-            return None
+            if r.status_code == 500 or r.status_code == 405:
+                error_json = r.json()
+                raise DSpaceServerError(
+                    message=error_json.get('message'),
+                    status=error_json.get('status'),
+                    error=error_json.get('error'),
+                    timestamp=error_json.get('timestamp'),
+                    path=error_json.get('path')
+                )
+            else:
+                # TODO: This is a hack to handle the case where the server returns a 404 or some
+                # other error code that isn't as 'unexpected', so we don't break older scripts for now
+                return None
         # ValueError / JSON handling moved to static method
         return parse_json(r)
 

dspace_rest_client/models.py

@@ -639,4 +639,23 @@ def as_dict(self):
             'sections': self.sections,
             'type': self.type
         }
-        return {**parent_dict, **dict}
+        return {**parent_dict, **dict}
+
+class DSpaceServerError(Exception):
+    """Exception raised when DSpace returns a 500 Internal Server Error response"""
+    def __init__(self, message, status=500, error=None, timestamp=None, path=None):
+        self.status = status
+        self.timestamp = timestamp
+        self.path = path
+        self.message = message
+        self.error = error
+        super().__init__(self.format_message())
+
+    def format_message(self):
+        parts = [f"DSpace Server Error ({self.status} {self.error})"]
+        if self.timestamp:
+            parts.append(f"Time: {self.timestamp}")
+        if self.path:
+            parts.append(f"Path: {self.path}")
+        parts.append(f"Message: {self.message}")
+        return " | ".join(parts)

example_exceptions.py

@@ -0,0 +1,64 @@
+# This software is licenced under the BSD 3-Clause licence
+# available at https://opensource.org/licenses/BSD-3-Clause
+# and described in the LICENCE file in the root of this project
+
+"""
+Example Python 3 application using the dspace.py API client library to retrieve basic DSOs in a 
+DSpace repository
+"""
+
+import sys
+import os
+from pprint import pprint
+
+from dspace_rest_client.client import DSpaceClient
+
+# Import models as below if needed
+from dspace_rest_client.models import Community, Collection, Item, Bundle, Bitstream, DSpaceServerError
+
+# Example variables needed for authentication and basic API requests
+# SET THESE TO MATCH YOUR TEST SYSTEM BEFORE RUNNING THE EXAMPLE SCRIPT
+# You can also leave them out of the constructor and set environment variables instead:
+# DSPACE_API_ENDPOINT=
+# DSPACE_API_USERNAME=
+# DSPACE_API_PASSWORD=
+# USER_AGENT=
+
+DEFAULT_URL = 'http://localhost:8080/server/api'
+DEFAULT_USERNAME = 'username@test.system.edu'
+DEFAULT_PASSWORD = 'password'
+
+# Configuration from environment variables
+URL = os.environ.get('DSPACE_API_ENDPOINT', DEFAULT_URL)
+USERNAME = os.environ.get('DSPACE_API_USERNAME', DEFAULT_USERNAME)
+PASSWORD = os.environ.get('DSPACE_API_PASSWORD', DEFAULT_PASSWORD)
+# Instantiate DSpace client
+# Note the 'fake_user_agent' setting here -- this will set a string like the following,
+# to get by Cloudfront:
+# Mozilla/5.0 (Windows NT 6.2; WOW64) AppleWebKit/537.36 (KHTML, like Gecko) \
+# Chrome/39.0.2171.95 Safari/537.36
+# The default is to *not* fake the user agent, and instead use the default of
+# DSpace-Python-REST-Client/x.y.z.
+# To specify a custom user agent, set the USER_AGENT env variable and leave/set
+# fake_user_agent as False
+d = DSpaceClient(
+    api_endpoint=URL, username=USERNAME, password=PASSWORD, fake_user_agent=True
+)
+
+# Authenticate against the DSpace client
+authenticated = d.authenticate()
+if not authenticated:
+    print("Error logging in! Giving up.")
+    sys.exit(1)
+
+# Forcing a 405 error to test (500 errors are handled too but are a bit harder to 'force' in a working system!)
+try:
+    r = d.fetch_resource(f"{d.API_ENDPOINT}/config/properties")
+    print(r.status_code)
+except DSpaceServerError as e:
+    # Here you can see the formatted error message
+    print("Here is a nice formatted error message:")
+    print(e.format_message())
+    # Here you can see a pretty print of the exception as dict, with the properties you can read
+    print("\nHere is the exception as a dict:")
+    pprint(e.__dict__)