[import] specify fk lookup field (#12180)

* Raise error on multiple matches

* add new field to handle lookup_field selection

* Add unit tests

* Update frontend

* Bump API version

* Ensure string-iness of lookup field

src/backend/InvenTree/InvenTree/api_version.py

@@ -1,11 +1,14 @@
 """InvenTree API version information."""
 
 # InvenTree API version
-INVENTREE_API_VERSION = 506
+INVENTREE_API_VERSION = 507
 """Increment this API version number whenever there is a significant change to the API that any clients need to know about."""
 
 INVENTREE_API_TEXT = """
 
+v507 -> 2026-06-16 : https://github.com/inventree/InvenTree/pull/12180
+    - Adds "lookup_field" parameter to the DataImportSessionSerializer, which allows for more flexible lookup of related objects during data import operations
+
 v506 -> 2026-06-15 : https://github.com/inventree/InvenTree/pull/12168
     - Reduce permissions scope for a number of API endpoints, to improve security and ensure that users only have access to the data they need
 

src/backend/InvenTree/importer/migrations/0006_dataimportcolumnmap_lookup_field.py

@@ -0,0 +1,24 @@
+# Generated migration
+
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("importer", "0005_dataimportsession_update_records"),
+    ]
+
+    operations = [
+        migrations.AddField(
+            model_name="dataimportcolumnmap",
+            name="lookup_field",
+            field=models.CharField(
+                blank=True,
+                null=True,
+                max_length=100,
+                verbose_name="Lookup Field",
+                help_text="Database field to use for foreign-key lookup. Leave blank for automatic lookup.",
+            ),
+        ),
+    ]

src/backend/InvenTree/importer/models.py

@@ -152,6 +152,36 @@ class DataImportSession(models.Model):
 
         return supported_models().get(self.model_type, None)
 
+    def get_lookup_fields_for_field(self, field_name: str) -> list:
+        """Return the valid lookup fields for a given related (FK) field.
+
+        Returns a list of field names that can be used as a lookup key,
+        consisting of 'pk' plus any fields defined in IMPORT_ID_FIELDS on the related model.
+        """
+        model = self.get_related_model(field_name)
+
+        if not model:
+            return ['pk']
+
+        id_fields = ['pk']
+
+        if custom_fields := getattr(model, 'IMPORT_ID_FIELDS', None):
+            id_fields += custom_fields
+
+        return id_fields
+
+    @property
+    def field_lookup_mapping(self) -> dict:
+        """Return a dict of field -> lookup_field mappings for this import session.
+
+        Only entries where lookup_field is explicitly set are included.
+        """
+        return {
+            mapping.field: mapping.lookup_field
+            for mapping in self.column_mappings.all()
+            if mapping.lookup_field
+        }
+
     def get_related_model(self, field_name: str) -> Optional[models.Model]:
         """Return the related model for a given field name.
 
@@ -408,6 +438,11 @@ class DataImportSession(models.Model):
                 if field.get('read_only', False):
                     continue
 
+                if field.get('type') == 'related field':
+                    field['lookup_fields'] = self.get_lookup_fields_for_field(
+                        field_name
+                    )
+
                 fields[field_name] = field
 
         # Cache the available fields against this instance
@@ -495,6 +530,22 @@ class DataImportColumnMap(models.Model):
         if field_def.get('read_only', False):
             raise DjangoValidationError({'field': _('Selected field is read-only')})
 
+        if self.lookup_field:
+            if field_def.get('type') != 'related field':
+                raise DjangoValidationError({
+                    'lookup_field': _(
+                        'Lookup field can only be set for related (foreign-key) fields'
+                    )
+                })
+
+            valid_lookup_fields = self.session.get_lookup_fields_for_field(self.field)
+            if self.lookup_field not in valid_lookup_fields:
+                raise DjangoValidationError({
+                    'lookup_field': _(
+                        'Invalid lookup field. Valid options are: {options}'
+                    ).format(options=', '.join(valid_lookup_fields))
+                })
+
     session = models.ForeignKey(
         DataImportSession,
         on_delete=models.CASCADE,
@@ -506,6 +557,16 @@ class DataImportColumnMap(models.Model):
 
     column = models.CharField(blank=True, max_length=100, verbose_name=_('Column'))
 
+    lookup_field = models.CharField(
+        blank=True,
+        null=True,
+        max_length=100,
+        verbose_name=_('Lookup Field'),
+        help_text=_(
+            'Database field to use for foreign-key lookup. Leave blank for automatic lookup.'
+        ),
+    )
+
     @property
     def available_fields(self):
         """Return a list of available fields for this import session.
@@ -638,9 +699,12 @@ class DataImportRow(models.Model):
         default_values = self.default_values
 
         data = {}
+        extract_errors = {}
 
         self.related_field_map = {}
 
+        field_lookup_mapping = self.session.field_lookup_mapping
+
         # We have mapped column (file) to field (serializer) already
         for field, col in field_mapping.items():
             # Data override (force value and skip any further checks)
@@ -668,7 +732,13 @@ class DataImportRow(models.Model):
             elif field_type == 'date':
                 value = self.convert_date_field(value)
             elif field_type == 'related field':
-                value = self.lookup_related_field(field, value)
+                try:
+                    value = self.lookup_related_field(
+                        field, value, lookup_field=field_lookup_mapping.get(field)
+                    )
+                except DjangoValidationError as exc:
+                    extract_errors[field] = exc.message
+                    continue
 
             # Use the default value, if provided
             if value is None and field in default_values:
@@ -710,6 +780,9 @@ class DataImportRow(models.Model):
 
         self.data = data
 
+        if extract_errors:
+            self.errors = extract_errors
+
         if commit:
             self.save()
 
@@ -733,7 +806,9 @@ class DataImportRow(models.Model):
         # If none of the formats matched, return the original value
         return value
 
-    def lookup_related_field(self, field_name: str, value: str) -> Optional[int]:
+    def lookup_related_field(
+        self, field_name: str, value: str, lookup_field: Optional[str] = None
+    ) -> Optional[int]:
         """Try to perform lookup against a related field.
 
         - This is used to convert a human-readable value (e.g. a supplier name) into a database reference (e.g. supplier ID).
@@ -742,6 +817,7 @@ class DataImportRow(models.Model):
         Arguments:
             field_name: The name of the field to perform the lookup against
             value: The value to be looked up
+            lookup_field: If provided, only query this specific model field (skips auto-lookup)
 
         Returns:
             A primary key value
@@ -765,21 +841,35 @@ class DataImportRow(models.Model):
                 'session': f'No related model found for field: {field_name}'
             })
 
-        valid_items = set()
-
         base_filters = (
             self.session.field_filters.get(field_name, {})
             if self.session.field_filters
             else {}
         )
 
-        # First priority is the PK (primary key) field
+        if lookup_field and type(lookup_field) is str:
+            # A specific lookup field has been chosen by the user — query only that field
+            try:
+                queryset = model.objects.filter(**{lookup_field: value}, **base_filters)
+            except ValueError:
+                return value
+
+            results = list(queryset[:2])
+
+            if len(results) == 1:
+                return results[0].pk
+
+            # Zero or multiple results — return raw value and let serializer report the error
+            return value
+
+        # Auto-lookup: try pk first, then any model-defined IMPORT_ID_FIELDS
         id_fields = ['pk']
 
         if custom_id_fields := getattr(model, 'IMPORT_ID_FIELDS', None):
             id_fields += custom_id_fields
 
-        # Iterate through the provided list - if any of the values match, we can perform the lookup
+        valid_items = set()
+
         for id_field in id_fields:
             try:
                 queryset = model.objects.filter(**{id_field: value}, **base_filters)
@@ -789,15 +879,19 @@ class DataImportRow(models.Model):
             # Evaluate at most two results to determine if there is exactly one match
             results = list(queryset[:2])
             if len(results) == 1:
-                # We have a single match against this field
                 valid_items.add(results[0].pk)
 
         if len(valid_items) == 1:
-            # We found a single valid match against the related model - return this value
             return valid_items.pop()
 
-        # We found either zero or multiple values matching against the related model
-        # Return the original value and let the serializer validation handle any errors against this field
+        if len(valid_items) > 1:
+            raise DjangoValidationError(
+                _(
+                    'Multiple matches found for value - please ensure the value is unique, or select a specific lookup field'
+                )
+            )
+
+        # No match found - return the original value and let the serializer validation handle it
         return value
 
     def serializer_data(self):
@@ -844,6 +938,10 @@ class DataImportRow(models.Model):
             # Row has already been completed
             return True
 
+        if self.errors:
+            # Errors were set during data extraction (e.g. ambiguous FK lookup)
+            return False
+
         if self.session.update_records:
             # Extract the ID field from the data
             instance_id = self.data.get(self.session.ID_FIELD_LABEL, None)

src/backend/InvenTree/importer/serializers.py

@@ -23,7 +23,15 @@ class DataImportColumnMapSerializer(InvenTreeModelSerializer):
         """Meta class options for the serializer."""
 
         model = importer.models.DataImportColumnMap
-        fields = ['pk', 'session', 'column', 'field', 'label', 'description']
+        fields = [
+            'pk',
+            'session',
+            'column',
+            'field',
+            'label',
+            'description',
+            'lookup_field',
+        ]
         read_only_fields = ['field', 'session']
 
     label = serializers.CharField(read_only=True)

src/backend/InvenTree/importer/tests.py

@@ -80,6 +80,72 @@ class ImporterTest(ImporterMixin, InvenTreeTestCase):
     def test_field_defaults(self):
         """Test default field values."""
 
+    def test_lookup_field_ambiguous_match(self):
+        """Test the behavior of lookup_related_field for ambiguous and pinned matches."""
+        from django.core.exceptions import ValidationError as DjangoValidationError
+
+        from part.models import Part, PartCategory
+
+        category = PartCategory.objects.create(
+            name='Test Category', description='Test category'
+        )
+
+        # Two parts which collide under different IMPORT_ID_FIELDS ('IPN' and 'name')
+        part_a = Part.objects.create(
+            category=category, name='Widget', description='desc', IPN='AMBIG-001'
+        )
+        Part.objects.create(
+            category=category, name='AMBIG-001', description='desc', IPN='WIDGET-002'
+        )
+
+        data_file = self.helper_file('companies.csv')
+        session = DataImportSession.objects.create(
+            data_file=data_file, model_type='stockitem'
+        )
+
+        row = DataImportRow(session=session)
+        row.related_field_map = {}
+
+        # Auto-lookup (no pinned lookup field) raises, as the value matches two different parts
+        with self.assertRaises(DjangoValidationError):
+            row.lookup_related_field('part', 'AMBIG-001')
+
+        # Pinning the lookup field to 'IPN' resolves the match unambiguously
+        result = row.lookup_related_field('part', 'AMBIG-001', lookup_field='IPN')
+        self.assertEqual(result, part_a.pk)
+
+        # Pinning the lookup field to 'name' resolves to the *other* part
+        result = row.lookup_related_field('part', 'AMBIG-001', lookup_field='name')
+        self.assertNotEqual(result, part_a.pk)
+
+    def test_lookup_field_validation(self):
+        """Test that DataImportColumnMap.clean() validates the lookup_field value."""
+        from django.core.exceptions import ValidationError as DjangoValidationError
+
+        data_file = self.helper_file('companies.csv')
+        session = DataImportSession.objects.create(
+            data_file=data_file, model_type='stockitem'
+        )
+
+        part_mapping = session.column_mappings.get(field='part')
+        quantity_mapping = session.column_mappings.get(field='quantity')
+
+        # Valid lookup field for a related (FK) field
+        part_mapping.lookup_field = 'IPN'
+        part_mapping.save()
+        part_mapping.refresh_from_db()
+        self.assertEqual(part_mapping.lookup_field, 'IPN')
+
+        # Invalid lookup field (not a valid IMPORT_ID_FIELDS option)
+        part_mapping.lookup_field = 'not_a_real_field'
+        with self.assertRaises(DjangoValidationError):
+            part_mapping.save()
+
+        # lookup_field cannot be set against a non-related field
+        quantity_mapping.lookup_field = 'IPN'
+        with self.assertRaises(DjangoValidationError):
+            quantity_mapping.save()
+
 
 class ImportAPITest(ImporterMixin, InvenTreeAPITestCase):
     """End-to-end tests for the importer API."""
@@ -181,6 +247,58 @@ class ImportAPITest(ImporterMixin, InvenTreeAPITestCase):
         # Check that there are new database records
         self.assertEqual(PartCategory.objects.count(), N + 4)
 
+    def test_column_mapping_lookup_field(self):
+        """Test that the 'lookup_field' option can be specified via the column-mapping API."""
+        f = self.helper_file('companies.csv')
+
+        session = DataImportSession.objects.create(
+            data_file=f, model_type='stockitem', user=self.user
+        )
+
+        self.assignRole('stock.change')
+
+        # available_fields should expose the valid lookup field options for the 'part' FK field
+        session_detail = self.get(
+            reverse('api-import-session-detail', kwargs={'pk': session.pk})
+        ).data
+        part_field_info = session_detail['available_fields']['part']
+        self.assertIn('lookup_fields', part_field_info)
+        self.assertIn('IPN', part_field_info['lookup_fields'])
+        self.assertIn('name', part_field_info['lookup_fields'])
+        self.assertIn('pk', part_field_info['lookup_fields'])
+
+        part_mapping = session.column_mappings.get(field='part')
+        quantity_mapping = session.column_mappings.get(field='quantity')
+
+        mapping_url = reverse(
+            'api-importer-mapping-detail', kwargs={'pk': part_mapping.pk}
+        )
+
+        # Initially, no lookup field is set (defaults to 'auto')
+        data = self.get(mapping_url).data
+        self.assertIn(data['lookup_field'], [None, ''])
+
+        # Set a valid lookup field
+        data = self.patch(mapping_url, {'lookup_field': 'IPN'}, expected_code=200).data
+        self.assertEqual(data['lookup_field'], 'IPN')
+
+        # Confirm it persists
+        data = self.get(mapping_url).data
+        self.assertEqual(data['lookup_field'], 'IPN')
+
+        # An invalid lookup field is rejected
+        self.patch(mapping_url, {'lookup_field': 'not_a_real_field'}, expected_code=400)
+
+        # Clear the lookup field (revert to 'auto')
+        data = self.patch(mapping_url, {'lookup_field': None}, expected_code=200).data
+        self.assertIn(data['lookup_field'], [None, ''])
+
+        # lookup_field cannot be set against a non-related field
+        quantity_url = reverse(
+            'api-importer-mapping-detail', kwargs={'pk': quantity_mapping.pk}
+        )
+        self.patch(quantity_url, {'lookup_field': 'IPN'}, expected_code=400)
+
     def test_session_list(self):
         """Test API endpoint which details the list of import sessions."""
         url = reverse('api-importer-session-list')

src/frontend/src/components/importer/ImporterColumnSelector.tsx

@@ -179,6 +179,55 @@ function ImporterDefaultField({
   );
 }
 
+function ImporterLookupFieldSelector({
+  column,
+  session
+}: Readonly<{ column: any; session: ImportSessionState }>) {
+  const api = useApi();
+
+  const fieldDef = session.availableFields[column.field];
+  const lookupFields: string[] = fieldDef?.lookup_fields ?? [];
+
+  const [selected, setSelected] = useState<string>(column.lookup_field ?? '');
+
+  useEffect(() => {
+    setSelected(column.lookup_field ?? '');
+  }, [column.lookup_field]);
+
+  if (lookupFields.length === 0) {
+    return null;
+  }
+
+  const options = [
+    { value: '', label: t`Auto` },
+    ...lookupFields.map((f: string) => ({ value: f, label: f }))
+  ];
+
+  const onChange = useCallback(
+    (value: string | null) => {
+      const next = value ?? '';
+      api
+        .patch(
+          apiUrl(ApiEndpoints.import_session_column_mapping_list, column.pk),
+          { lookup_field: next || null }
+        )
+        .then(() => setSelected(next))
+        .catch(() => {});
+    },
+    [column.pk]
+  );
+
+  return (
+    <Select
+      aria-label={`import-lookup-field-${column.field}`}
+      data={options}
+      value={selected}
+      onChange={onChange}
+      size='sm'
+    />
+  );
+}
+
 function ImporterColumnTableRow({
   session,
   column,
@@ -210,6 +259,9 @@ function ImporterColumnTableRow({
       <Table.Td>
         <ImporterColumn column={column} options={options} />
       </Table.Td>
+      <Table.Td>
+        <ImporterLookupFieldSelector column={column} session={session} />
+      </Table.Td>
       <Table.Td>
         <ImporterDefaultField
           fieldName={column.field}
@@ -285,6 +337,7 @@ export default function ImporterColumnSelector({
             <Table.Th>{t`Database Field`}</Table.Th>
             <Table.Th>{t`Field Description`}</Table.Th>
             <Table.Th>{t`Imported Column`}</Table.Th>
+            <Table.Th>{t`Lookup Field`}</Table.Th>
             <Table.Th>{t`Default Value`}</Table.Th>
           </Table.Tr>
         </Table.Thead>