Use a custom filter to work around access to fields with spaces

src/documents/file_handling.py

@@ -26,7 +26,10 @@ INVALID_VARIABLE_STR = "InvalidVarError"
 filepath_engine = Engine(
     autoescape=False,
     string_if_invalid=f"{INVALID_VARIABLE_STR}: %s",
-    libraries={"filepath": "documents.templatetags.filepath"},
+    libraries={
+        "filepath": "documents.templatetags.filepath",
+        "get_cf_value": "documents.templatetags.get_cf_value",
+    },
 )
 
 
@@ -330,7 +333,9 @@ def validate_template_and_render(
     try:
         # We load the custom tag used to remove spaces and newlines from the final string around the user string
         template = filepath_engine.from_string(
-            "{% load filepath %}{% filepath %}" + template_string + "{% endfilepath %}",
+            "{% load filepath %}{% load get_cf_value %}{% filepath %}"
+            + template_string
+            + "{% endfilepath %}",
         )
         rendered_template = template.render(Context(context))
 

src/documents/serialisers.py

@@ -54,7 +54,7 @@ from documents.models import WorkflowTrigger
 from documents.parsers import is_mime_type_supported
 from documents.permissions import get_groups_with_only_permission
 from documents.permissions import set_permissions_for_object
-from documents.templatetags import convert_to_django_template_format
+from documents.templatetags.filepath import convert_to_django_template_format
 from documents.validators import uri_validator
 
 logger = logging.getLogger("paperless.serializers")

src/documents/templatetags/get_cf_value.py

@@ -0,0 +1,12 @@
+from django import template
+
+register = template.Library()
+
+
+@register.filter("get_cf_value")
+def get_cf_value(custom_field_data: dict[str, dict[str, str]], name: str):
+    """
+    See https://stackoverflow.com/questions/2970244/django-templates-value-of-dictionary-key-with-a-space-in-it/2970337#2970337
+    """
+    data = custom_field_data[name]["value"]
+    return data

src/documents/tests/test_file_handling.py

@@ -1245,17 +1245,6 @@ class TestFilenameGeneration(DirectoriesMixin, TestCase):
             )
 
     def test_template_with_custom_fields(self):
-        sp = StoragePath.objects.create(
-            name="sp1",
-            path="""
-                 {% if "Invoice" in custom_fields %}
-                   invoices/{{ custom_fields.Invoice.value }}
-                 {% else %}
-                   not-invoices/{{ title }}
-                 {% endif %}
-                 """,
-        )
-
         doc_a = Document.objects.create(
             title="Some Title",
             created=timezone.make_aware(datetime.datetime(2020, 6, 25, 7, 36, 51, 153)),
@@ -1264,7 +1253,6 @@ class TestFilenameGeneration(DirectoriesMixin, TestCase):
             pk=2,
             checksum="2",
             archive_serial_number=25,
-            storage_path=sp,
         )
 
         cf = CustomField.objects.create(
@@ -1278,17 +1266,32 @@ class TestFilenameGeneration(DirectoriesMixin, TestCase):
             value_int=1234,
         )
 
-        self.assertEqual(
-            generate_filename(doc_a),
-            "invoices/1234.pdf",
-        )
+        with override_settings(
+            FILENAME_FORMAT="""
+                 {% if "Invoice" in custom_fields %}
+                   invoices/{{ custom_fields|get_cf_value:'Invoice' }}
+                 {% else %}
+                   not-invoices/{{ title }}
+                 {% endif %}
+                 """,
+        ):
+            self.assertEqual(
+                generate_filename(doc_a),
+                "invoices/1234.pdf",
+            )
 
-        cfi.delete()
+        cf.name = "Invoice Number"
+        cfi.value_int = 4567
+        cfi.save()
+        cf.save()
 
-        self.assertEqual(
-            generate_filename(doc_a),
-            "not-invoices/Some Title.pdf",
-        )
+        with override_settings(
+            FILENAME_FORMAT="invoices/{{ custom_fields|get_cf_value:'Invoice Number' }}",
+        ):
+            self.assertEqual(
+                generate_filename(doc_a),
+                "invoices/4567.pdf",
+            )
 
     def test_using_other_filters(self):
         doc_a = Document.objects.create(