Properly deal with empty responses

CHANGELOG.md

@@ -12,6 +12,11 @@ NOTE: potentially breaking changes are flagged with a 🧨 symbol.
   be None (in which case a fixed string is returned).
 - `pyppms.booking.PpmsBooking.desc` has been added as a property to retrieve a
   shorter description of the object than calling `str()` on it.
+- `pyppms.exceptions.NoDataError` has been added to indicate a PUMAPI response
+  did *not* contain any useful data.
+- `pyppms.common.parse_multiline_response()` will now raise the newly added
+  `NoDataError` in case the requested *runningsheet* for a day doesn't contain
+  any bookings to allow for properly dealing with "empty" days.
 
 ### Changed
 

src/pyppms/common.py

@@ -8,6 +8,8 @@
 
 from loguru import logger as log
 
+from .exceptions import NoDataError
+
 
 def process_response_values(values):
     """Process (in-place) a list of strings, remove quotes, detect boolean etc.
@@ -120,11 +122,15 @@ def parse_multiline_response(text, graceful=True):
     -------
     list(dict)
         A list with dicts where the latter ones have the same form as produced
-        by the dict_from_single_response() function. Note that when graceful
+        by the dict_from_single_response() function. May be empty in case the
+        PUMAPI response didn't contain any useful data. Note that when graceful
         mode is requested, consistency among the dicts is not guaranteed.
 
     Raises
     ------
+    NoDataError
+        Raised when the response text was too short (less than two lines) and
+        the `graceful` parameter has been set to false.
     ValueError
         Raised when the response text is inconsistent and the `graceful`
         parameter has been set to false, or if parsing fails for any other
@@ -134,10 +140,10 @@ def parse_multiline_response(text, graceful=True):
     try:
         lines = text.splitlines()
         if len(lines) < 2:
-            log.warning("Response expected to have two or more lines: {}", text)
+            log.info("Response has less than TWO lines: >>>{}<<<", text)
             if not graceful:
-                raise ValueError("Invalid response format!")
-            return parsed
+                raise NoDataError("Invalid response format!")
+            return []
 
         header = lines[0].split(",")
         for i, entry in enumerate(header):
@@ -174,6 +180,9 @@ def parse_multiline_response(text, graceful=True):
             )
             log.warning(msg)
 
+    except NoDataError as err:
+        raise err
+
     except Exception as err:
         msg = f"Unable to parse data returned by PUMAPI: {text} - ERROR: {err}"
         log.error(msg)

src/pyppms/exceptions.py

@@ -0,0 +1,5 @@
+"""PyPPMS exception classes."""
+
+
+class NoDataError(ValueError):
+    """Exception indicating no data was received from PUMAPI."""

src/pyppms/ppms.py

@@ -20,6 +20,7 @@
 from .user import PpmsUser
 from .system import PpmsSystem
 from .booking import PpmsBooking
+from .exceptions import NoDataError
 
 
 class PpmsConnection:
@@ -596,12 +597,14 @@ def get_running_sheet(self, core_facility_ref, date, ignore_uncached_users=False
         response = self.request("getrunningsheet", parameters)
         try:
             entries = parse_multiline_response(response.text, graceful=False)
+        except NoDataError:
+            # in case no bookings exist the response will be empty!
+            log.debug("Runningsheet for the given day was empty!")
+            return []
         except Exception as err:  # pylint: disable-msg=broad-except
             log.error("Parsing runningsheet details failed: {}", err)
-            # NOTE: in case no future bookings exist the response will be empty!
-            log.error("Possibly the runningsheet is empty as no bookings exist?")
-            log.debug("Runningsheet PUMPAI response was: {}", response.text)
-            return bookings
+            log.debug("Runningsheet PUMPAI response was: >>>{}<<<", response.text)
+            return []
 
         for entry in entries:
             full = entry["User"]