catch CALCATAPIError and create exception classes for two cases in webservice

webservice/messages.py

@@ -33,6 +33,16 @@ class MDC:
     NOTHING_TO_DO = "Nothing to calibrate for this run, copied raw data only"
 
 
+class PDUsNotFoundError(Exception):
+    """Exception raised when a detector cannot be found."""
+    pass
+
+
+class OperationModeNotFoundError(Exception):
+    """Exception raised when an operation mode cannot be found for a given detector."""
+    pass
+
+
 class Success:
     UPLOADED_CONFIG = "SUCCESS: Uploaded config for cycle {}, proposal {}"
     START_CORRECTION = "SUCCESS: Started correction: proposal {}, run {}"

webservice/webservice.py

@@ -31,10 +31,17 @@ from metadata_client.metadata_client import MetadataClient
 
 try:
     from .config import webservice as config
-    from .messages import MDC, Errors, MigrationError, Success
+    from .messages import (
+        MDC,
+        Errors,
+        MigrationError,
+        OperationModeNotFoundError,
+        PDUsNotFoundError,
+        Success,
+    )
 except ImportError:
     from config import webservice as config
-    from messages import MDC, Errors, MigrationError, Success
+    from messages import MDC, Errors, MigrationError, Success, PDUsNotFoundError, OperationModeNotFoundError
 
 from cal_tools.calcat_interface2 import get_client
 
@@ -347,23 +354,37 @@ def get_number_of_characterization_runs(karabo_id, operation_mode):
     """
     client = get_client()
     detector_id = client.detector_by_identifier(karabo_id)['id']
-
-    pdus = client.get(
-        'physical_detector_units/get_all_by_detector?'
-        f'detector_id={detector_id}')
-    first_pdu_id = pdus[0]['detector_type']['id']
-    operation_modes = client.get(
-        'operation_modes/get_all_by_detector_type?'
-        f'detector_type_id={first_pdu_id}')
+    try:
+        pdus = client.get(
+            'physical_detector_units/get_all_by_detector?'
+            f'detector_id={detector_id}')
+        if len(pdus) == 0:
+            raise PDUsNotFoundError
+    except Exception as e:
+        raise PDUsNotFoundError(
+            f'Failed to find physical detector units for {karabo_id}: {e}')
+
+    det_type = pdus[0]['detector_type']
+    try:
+        operation_modes = client.get(
+            'operation_modes/get_all_by_detector_type?'
+            f'detector_type_id={det_type["id"]}')
+        if len(operation_modes) == 0:
+            raise OperationModeNotFoundError
+    except Exception as e:
+        raise OperationModeNotFoundError(
+            f'Failed to find operation modes for {det_type["name"]}: {e}')
 
     number_of_runs = next(
         (
             mode['number_of_runs'] for mode in operation_modes
             if mode['identifier'] == operation_mode),
         None)
+
     if number_of_runs is None:
-        raise ValueError(
-            f"{karabo_id} doesn't have this operation mode {operation_mode}.")
+        raise OperationModeNotFoundError(
+            f'{karabo_id} does not have this operation mode {operation_mode}.')
+
     return number_of_runs