JP-4075: Raise error for no slits selected (#9794)

Author: melanieclarke

changes/9794.extract_2d.rst

@@ -0,0 +1 @@
+If the ``slit_names`` or ``source_ids`` are specified, but none of the slits are valid, a ``NoDataOnDetectorError`` exception is raised.

docs/jwst/extract_2d/main.rst

@@ -306,6 +306,8 @@ modes. For NIRSpec observations there is one applicable argument:
   of None will cause all known slits for the instrument to be extracted.
 
 ``slit_names`` and ``source_ids`` can be used at the same time, duplicates will be filtered out.
+If either argument is specified, but no valid slits are identified, an error will be
+raised and the step will exit.
 
 There are several arguments available for Wide-Field Slitless Spectroscopy (WFSS) and
 Time-Series (TSO) grism spectroscopy:

jwst/extract_2d/extract_2d_step.py

@@ -39,15 +39,16 @@ def process(self, input_model):
         output_model : DataModel
             The resulting DataModel of the extract_2d step
         """
-        reference_file_names = {}
-        if input_model.meta.exposure.type in extract_2d.slitless_modes:
-            # The wavelengthrange file is used only by the WFSS modes.
-            # If retrieved by a Nirspec mode, it would override the name of
-            # the file in meta.ref_file if a custom file was used.
-            for reftype in self.reference_file_types:
-                reffile = self.get_reference_file(input_model, reftype)
-                reference_file_names[reftype] = reffile if reffile else ""
         with datamodels.open(input_model) as dm:
+            reference_file_names = {}
+            if dm.meta.exposure.type in extract_2d.slitless_modes:
+                # The wavelengthrange file is used only by the WFSS modes.
+                # If retrieved by a Nirspec mode, it would override the name of
+                # the file in meta.ref_file if a custom file was used.
+                for reftype in self.reference_file_types:
+                    reffile = self.get_reference_file(input_model, reftype)
+                    reference_file_names[reftype] = reffile if reffile else ""
+
             output_model = extract_2d.extract2d(
                 dm,
                 self.slit_names,

jwst/extract_2d/nirspec.py

@@ -65,7 +65,8 @@ def nrs_extract2d(input_model, slit_names=None, source_ids=None):
     open_slits = input_model.meta.wcs.get_transform("gwa", "slit_frame").slits
 
     # Select the slits to process
-    open_slits = select_slits(open_slits, slit_names, source_ids)
+    if slit_names is not None or source_ids is not None:
+        open_slits = select_slits(open_slits, slit_names, source_ids)
 
     # NIRSpec BRIGHTOBJ (S1600A1 TSO) mode
     if exp_type == "NRS_BRIGHTOBJ":
@@ -146,6 +147,11 @@ def select_slits(open_slits, slit_names, source_ids):
     -------
     selected_open_slits : list
         List of slits selected by slit_name or source_id
+
+    Raises
+    ------
+    `~jwst.assign_wcs.util.NoDataOnDetectorError`
+        If no valid slits are selected.
     """
     open_slit_names = [str(x.name) for x in open_slits]
     open_slit_source_ids = [str(x.source_id) for x in open_slits]
@@ -156,7 +162,7 @@ def select_slits(open_slits, slit_names, source_ids):
             if this_slit in open_slit_names:
                 matched_slits.append(this_slit)
             else:
-                log.warn(f"Slit {this_slit} is not in the list of open slits.")
+                log.warning(f"Slit {this_slit} is not in the list of open slits.")
         for sub in open_slits:
             if str(sub.name) in matched_slits:
                 selected_open_slits.append(sub)
@@ -166,7 +172,7 @@ def select_slits(open_slits, slit_names, source_ids):
             if this_id in open_slit_source_ids:
                 matched_sources.append(this_id)
             else:
-                log.warn(f"Source id {this_id} is not in the list of open slits.")
+                log.warning(f"Source id {this_id} is not in the list of open slits.")
         for sub in open_slits:
             if str(sub.source_id) in matched_sources:
                 if sub not in selected_open_slits:
@@ -179,8 +185,9 @@ def select_slits(open_slits, slit_names, source_ids):
             log.info(f"Name: {this_slit.name}, source_id: {this_slit.source_id}")
         return selected_open_slits
     else:
-        log.info("All slits selected")
-        return open_slits
+        log_message = "No valid slits selected."
+        log.critical(log_message)
+        raise util.NoDataOnDetectorError(log_message)
 
 
 def process_slit(input_model, slit):
@@ -363,7 +370,7 @@ class DitherMetadataError(Exception):
     Handle DitherMetadataError exception.
 
     This exception is raised if a Slit object doesn't have the required
-    dither attribute, or the x_ and y_ offsets aren't numeric.
+    dither attribute, or the x and y offsets aren't numeric.
     """
 
     pass

jwst/extract_2d/tests/test_nirspec.py

@@ -6,6 +6,7 @@
 from stdatamodels.jwst.transforms.models import Slit
 
 from jwst.assign_wcs import AssignWcsStep
+from jwst.assign_wcs.util import NoDataOnDetectorError
 from jwst.extract_2d.extract_2d_step import Extract2dStep
 from jwst.extract_2d.nirspec import select_slits
 
@@ -273,26 +274,43 @@ def test_extract_2d_nirspec_bots(nirspec_bots_rateints):
 
 def test_select_slits(nirspec_slit_list):
     slit_list = nirspec_slit_list
-    # Choose all slits
-    all_slits = select_slits(slit_list, None, None)
-    assert all_slits == slit_list
+
+    # No slits selected
+    with pytest.raises(NoDataOnDetectorError, match="No valid slits selected"):
+        select_slits(slit_list, None, None)
+    with pytest.raises(NoDataOnDetectorError, match="No valid slits selected"):
+        select_slits(slit_list, [], [])
+    with pytest.raises(NoDataOnDetectorError, match="No valid slits selected"):
+        select_slits(slit_list, ["-99"], [-9999])
+
     # Just slit with name=='3'
     single_name = select_slits(slit_list, ["3"], None)
     assert single_name[0].name == "3"
     assert single_name[0].source_id == "3000"
+
     # Just slit with source_id == '3000'
     single_id = select_slits(slit_list, None, ["2000"])
     assert single_id[0].name == "2"
     assert single_id[0].source_id == "2000"
+
     # Slits with name == '4' and source_id == '4000' are duplicates
     duplicates = select_slits(slit_list, ["1", "4"], ["2000", "4000"])
     assert Slit(name="1", source_id="1000") in duplicates
     assert Slit(name="2", source_id="2000") in duplicates
     assert Slit(name="4", source_id="4000") in duplicates
+
     # Select slit with a non-integer name
     non_integer = select_slits(slit_list, ["S200A1"], None)
     assert non_integer[0] == Slit(name="S200A1", source_id="2222")
+
     # Select slits with mix of integer and string names
     with_integer = select_slits(slit_list, [2, "5"], None)
     assert Slit(name="2", source_id="2000") in with_integer
     assert Slit(name="5", source_id="5000") in with_integer
+
+    # Select some valid, some invalid slits
+    some_valid = select_slits(slit_list, ["1", "4", "-99"], ["2000", "4000", "-9999"])
+    assert len(some_valid) == 3
+    assert Slit(name="1", source_id="1000") in some_valid
+    assert Slit(name="2", source_id="2000") in some_valid
+    assert Slit(name="4", source_id="4000") in some_valid