Fix check for empty string values

CHANGES.md

@@ -1,6 +1,9 @@
 # Dicom Validator Release Notes
 The released versions correspond to PyPi releases.
 
+### Fixes
+* fixed handling of empty type 2 enumerated values (see [#147](../../issues/147))
+
 ### Infrastructure
 * update the tests for current version 2024e
 

dicom_validator/tests/validator/test_iod_validator.py

@@ -476,6 +476,53 @@ def test_invalid_enum_value(self, validator):
             "(value: 1, allowed: 8, 9, 10, 11, 12, 13, 14, 15, 16)",
         )
 
+    @pytest.mark.tag_set(
+        {
+            "SOPClassUID": uid.EnhancedXAImageStorage,
+            "PatientName": "XXX",
+            "PatientID": "ZZZ",
+            "ImageType": "DERIVED",
+            "PresentationLUTShape": "",
+        }
+    )
+    def test_empty_type_1_enum_value(self, validator):
+        result = validator.validate()
+
+        # Presentation LUT Shape: incorrect enum value
+        assert has_tag_error(
+            result,
+            "Enhanced XA/XRF Image",
+            "(2050,0020)",
+            "is empty",
+        )
+
+    @pytest.mark.tag_set(
+        {
+            "SOPClassUID": uid.OphthalmicPhotography8BitImageStorage,
+            "PatientName": "XXX",
+            "PatientID": "ZZZ",
+            "PatientEyeMovementCommanded": "",
+            "PupilDilated": "",
+        }
+    )
+    def test_empty_type_2_enum_value(self, validator):
+        # regression test for #147
+        result = validator.validate()
+
+        assert not has_tag_error(
+            result,
+            "Ophthalmic Photography Acquisition Parameters",
+            "(0022,0005)",
+            "value is not allowed",
+        )
+
+        assert not has_tag_error(
+            result,
+            "Ophthalmic Photography Acquisition Parameters",
+            "(0022,000D)",
+            "value is not allowed",
+        )
+
     @pytest.mark.tag_set(
         {
             "SOPClassUID": uid.MRImageStorage,

dicom_validator/validator/iod_validator.py

@@ -391,9 +391,9 @@ def _validate_attribute(self, tag_id, attribute):
             value = self._dataset_stack[-1].dataset[tag_id].value
             vr = self._dataset_stack[-1].dataset[tag_id].VR
             if value_required:
-                if value is None or isinstance(value, Sequence) and not value:
+                if value is None or isinstance(value, (Sequence, str)) and not value:
                     error_kind = "empty"
-            if value is not None:
+            if value is not None and (not isinstance(value, str) or value):
                 if not isinstance(value, MultiValue):
                     value = [value]
                 for i, v in enumerate(value):