Automatically prune removed options from existing instances

src/documents/management/commands/document_importer.py

@@ -34,7 +34,7 @@ from documents.settings import EXPORTER_ARCHIVE_NAME
 from documents.settings import EXPORTER_CRYPTO_SETTINGS_NAME
 from documents.settings import EXPORTER_FILE_NAME
 from documents.settings import EXPORTER_THUMBNAIL_NAME
-from documents.signals.handlers import update_cf_instance_documents
+from documents.signals.handlers import check_paths_and_prune_custom_fields
 from documents.signals.handlers import update_filename_and_move_files
 from documents.utils import copy_file_with_basic_stats
 from paperless import version
@@ -262,7 +262,7 @@ class Command(CryptMixin, BaseCommand):
             ),
             disable_signal(
                 post_save,
-                receiver=update_cf_instance_documents,
+                receiver=check_paths_and_prune_custom_fields,
                 sender=CustomField,
             ),
         ):

src/documents/signals/handlers.py

@@ -367,21 +367,6 @@ class CannotMoveFilesException(Exception):
     pass
 
 
-# should be disabled in /src/documents/management/commands/document_importer.py handle
-@receiver(models.signals.post_save, sender=CustomField)
-def update_cf_instance_documents(sender, instance: CustomField, **kwargs):
-    """
-    'Select' custom field instances get their end-user value (e.g. in file names) from the select_options in extra_data,
-    which is contained in the custom field itself. So when the field is changed, we (may) need to update the file names
-    of all documents that have this custom field.
-    """
-    if (
-        instance.data_type == CustomField.FieldDataType.SELECT
-    ):  # Only select fields, for now
-        for cf_instance in instance.fields.all():
-            update_filename_and_move_files(sender, cf_instance)
-
-
 # should be disabled in /src/documents/management/commands/document_importer.py handle
 @receiver(models.signals.post_save, sender=CustomFieldInstance)
 @receiver(models.signals.m2m_changed, sender=Document.tags.through)
@@ -520,6 +505,34 @@ def update_filename_and_move_files(
             )
 
 
+# should be disabled in /src/documents/management/commands/document_importer.py handle
+@receiver(models.signals.post_save, sender=CustomField)
+def check_paths_and_prune_custom_fields(sender, instance: CustomField, **kwargs):
+    """
+    When a custom field is updated:
+    1. 'Select' custom field instances get their end-user value (e.g. in file names) from the select_options in extra_data,
+    which is contained in the custom field itself. So when the field is changed, we (may) need to update the file names
+    of all documents that have this custom field.
+    2. If a 'Select' field option was removed, we need to nullify the custom field instances that have the option.
+    """
+    if (
+        instance.data_type == CustomField.FieldDataType.SELECT
+    ):  # Only select fields, for now
+        for cf_instance in instance.fields.all():
+            options = instance.extra_data.get("select_options", [])
+            try:
+                next(
+                    option["label"]
+                    for option in options
+                    if option["id"] == cf_instance.value
+                )
+            except StopIteration:
+                # The value of this custom field instance is not in the select options anymore
+                cf_instance.value_select = None
+                cf_instance.save()
+            update_filename_and_move_files(sender, cf_instance)
+
+
 def set_log_entry(sender, document: Document, logging_group=None, **kwargs):
     ct = ContentType.objects.get(model="document")
     user = User.objects.get(username="consumer")

src/documents/tests/test_api_custom_fields.py

@@ -209,6 +209,69 @@ class TestCustomFieldsAPI(DirectoriesMixin, APITestCase):
             ],
         )
 
+    def test_custom_field_select_options_pruned(self):
+        """
+        GIVEN:
+            - Select custom field exists and document instance with one of the options
+        WHEN:
+            - API request to remove an option from the select field
+        THEN:
+            - The option is removed from the field
+            - The option is removed from the document instance
+        """
+        custom_field_select = CustomField.objects.create(
+            name="Select Field",
+            data_type=CustomField.FieldDataType.SELECT,
+            extra_data={
+                "select_options": [
+                    {"label": "Option 1", "id": "abc-123"},
+                    {"label": "Option 2", "id": "def-456"},
+                    {"label": "Option 3", "id": "ghi-789"},
+                ],
+            },
+        )
+
+        doc = Document.objects.create(
+            title="WOW",
+            content="the content",
+            checksum="123",
+            mime_type="application/pdf",
+        )
+        CustomFieldInstance.objects.create(
+            document=doc,
+            field=custom_field_select,
+            value_text="abc-123",
+        )
+
+        resp = self.client.patch(
+            f"{self.ENDPOINT}{custom_field_select.id}/",
+            json.dumps(
+                {
+                    "extra_data": {
+                        "select_options": [
+                            {"label": "Option 1", "id": "abc-123"},
+                            {"label": "Option 3", "id": "ghi-789"},
+                        ],
+                    },
+                },
+            ),
+            content_type="application/json",
+        )
+        self.assertEqual(resp.status_code, status.HTTP_200_OK)
+
+        data = resp.json()
+
+        self.assertCountEqual(
+            data["extra_data"]["select_options"],
+            [
+                {"label": "Option 1", "id": "abc-123"},
+                {"label": "Option 3", "id": "ghi-789"},
+            ],
+        )
+
+        doc.refresh_from_db()
+        self.assertEqual(doc.custom_fields.first().value, None)
+
     def test_create_custom_field_monetary_validation(self):
         """
         GIVEN: