Support custom fields in workflow title templates

docs/usage.md

@@ -726,6 +726,7 @@ applied. You can use the following placeholders in the template with any trigger
 - `{{added_time}}`: added time in HH:MM format
 - `{{original_filename}}`: original file name without extension
 - `{{filename}}`: current file name without extension (for "added" workflows this may not be final yet, you can use `{{original_filename}}`)
+- `{{custom_fields}}` (title assignments only): Custom field names mapped to their type and value, as in [file name templates](advanced_usage.md#additional-variables). For example, `{{ custom_fields.Invoice.value }}` or `{{ custom_fields | get_cf_value("Invoice", "") }}` for a fallback when the field is missing. In title assignments, fields assigned by the same action are available.
 - `{{doc_title}}`: current document title (cannot be used in title assignment)
 
 The following placeholders are only available for "added" or "updated" triggers

src/documents/consumer.py

@@ -847,6 +847,19 @@ class ConsumerPlugin(
             local_added,
             self.filename,
             self.filename,
+            custom_fields=[
+                CustomFieldInstance(
+                    field=field,
+                    **{
+                        CustomFieldInstance.get_value_field_name(
+                            field.data_type,
+                        ): self.metadata.custom_fields[field.pk],
+                    },
+                )
+                for field in CustomField.objects.filter(
+                    pk__in=self.metadata.custom_fields or {},
+                )
+            ],
         )
 
     def _store(

src/documents/templating/workflows.py

@@ -1,4 +1,5 @@
 import logging
+from collections.abc import Iterable
 from datetime import date
 from datetime import datetime
 from pathlib import Path
@@ -13,7 +14,9 @@ from jinja2 import make_logging_undefined
 from jinja2.meta import find_undeclared_variables
 from jinja2.sandbox import SecurityError
 
+from documents.models import CustomFieldInstance
 from documents.templating.environment import _template_environment
+from documents.templating.filepath import get_custom_fields_context
 from documents.templating.filters import format_datetime
 from documents.templating.filters import localize_date
 
@@ -56,6 +59,7 @@ _known_placeholder_names = {
     "doc_title",
     "doc_url",
     "doc_id",
+    "custom_fields",
 }
 
 
@@ -86,6 +90,7 @@ def parse_w_workflow_placeholders(
     doc_title: str | None = None,
     doc_url: str | None = None,
     doc_id: int | None = None,
+    custom_fields: Iterable[CustomFieldInstance] = (),
 ) -> str:
     """
     Available title placeholders for Workflows depend on what has already been assigned,
@@ -108,6 +113,7 @@ def parse_w_workflow_placeholders(
         "original_filename": Path(original_filename).stem,
         "filename": Path(filename).stem,
     }
+    formatting.update(get_custom_fields_context(custom_fields))
     if created is not None:
         formatting.update(
             {

src/documents/tests/test_workflows.py

@@ -1846,6 +1846,50 @@ class TestWorkflows(
             expected_str = f"Document storage path {doc.storage_path} does not match {trigger.filter_has_storage_path}"
             self.assertIn(expected_str, cm.output[1])
 
+    def test_title_custom_fields(self) -> None:
+        from documents.consumer import ConsumerPlugin
+        from documents.templating.workflows import validate_workflow_template
+
+        field = CustomField.objects.create(
+            name="Invoice",
+            data_type=CustomField.FieldDataType.STRING,
+        )
+        template = '{{ custom_fields.Invoice.value }} {{ custom_fields | get_cf_value("Missing", "fallback") }}'
+        validate_workflow_template(template)
+        consumer = mock.Mock(
+            filename="invoice.pdf",
+            metadata=DocumentMetadataOverrides(custom_fields={field.pk: "INV-123"}),
+        )
+        self.assertEqual(
+            ConsumerPlugin._parse_title_placeholders(consumer, template),
+            "INV-123 fallback",
+        )
+        trigger = WorkflowTrigger.objects.create(
+            type=WorkflowTrigger.WorkflowTriggerType.DOCUMENT_ADDED,
+        )
+        action = WorkflowAction.objects.create(assign_title=template)
+        doc = Document.objects.create(title="Original")
+        action.assign_custom_fields.add(field)
+        action.assign_custom_fields_values = {str(field.pk): "INV-123"}
+        action.save()
+        workflow = Workflow.objects.create(name="Custom field title", order=0)
+        workflow.triggers.add(trigger)
+        workflow.actions.add(action)
+
+        document_consumption_finished.send(sender=self.__class__, document=doc)
+
+        doc.refresh_from_db()
+        self.assertEqual(doc.title, "INV-123 fallback")
+
+        # Existing fields remain available when the action assigns no custom fields.
+        action.assign_custom_fields.clear()
+        CustomFieldInstance.objects.filter(document=doc, field=field).update(
+            value_text="INV-456",
+        )
+        document_consumption_finished.send(sender=self.__class__, document=doc)
+        doc.refresh_from_db()
+        self.assertEqual(doc.title, "INV-456 fallback")
+
     def test_document_added_invalid_title_placeholders(self) -> None:
         """
         GIVEN:

src/documents/workflows/mutations.py

@@ -43,6 +43,33 @@ def apply_assignment_to_document(
     if action.assign_owner:
         document.owner = action.assign_owner
 
+    if action.has_assign_custom_fields:
+        for field in action.assign_custom_fields.all():
+            value_field_name = CustomFieldInstance.get_value_field_name(
+                data_type=field.data_type,
+            )
+            args = {
+                value_field_name: action.assign_custom_fields_values.get(
+                    str(field.pk),
+                    None,
+                ),
+            }
+            # for some reason update_or_create doesn't work here
+            instance = CustomFieldInstance.objects.filter(
+                field=field,
+                document=document,
+            ).first()
+            # empty string is indistinguishable from no value in the UI
+            if instance and args[value_field_name] not in (None, ""):
+                setattr(instance, value_field_name, args[value_field_name])
+                instance.save()
+            elif not instance:
+                CustomFieldInstance.objects.create(
+                    **args,
+                    field=field,
+                    document=document,
+                )
+
     if action.assign_title:
         try:
             title = parse_w_workflow_placeholders(
@@ -57,6 +84,9 @@ def apply_assignment_to_document(
                 "",  # dont pass the title to avoid recursion
                 "",  # no urls in titles
                 document.pk,
+                custom_fields=CustomFieldInstance.global_objects.filter(
+                    document=document,
+                ).select_related("field"),
             )
             if title:
                 document.title = title
@@ -91,33 +121,6 @@ def apply_assignment_to_document(
             merge=True,
         )
 
-    if action.has_assign_custom_fields:
-        for field in action.assign_custom_fields.all():
-            value_field_name = CustomFieldInstance.get_value_field_name(
-                data_type=field.data_type,
-            )
-            args = {
-                value_field_name: action.assign_custom_fields_values.get(
-                    str(field.pk),
-                    None,
-                ),
-            }
-            # for some reason update_or_create doesn't work here
-            instance = CustomFieldInstance.objects.filter(
-                field=field,
-                document=document,
-            ).first()
-            # empty string is indistinguishable from no value in the UI
-            if instance and args[value_field_name] not in (None, ""):
-                setattr(instance, value_field_name, args[value_field_name])
-                instance.save()
-            elif not instance:
-                CustomFieldInstance.objects.create(
-                    **args,
-                    field=field,
-                    document=document,
-                )
-
 
 def apply_assignment_to_overrides(
     action: WorkflowAction,