Data import fix (#12568)

* Specify JSON encoder for data import fields

- Fixes encoding issues when importing from XLSX file

* Add regression test

* Fix faulty error handler

* Fix for unit test

src/backend/InvenTree/importer/migrations/0008_alter_dataimportrow_data_alter_dataimportrow_errors_and_more.py

@@ -0,0 +1,88 @@
+# Generated by Django 5.2.16 on 2026-08-08 01:36
+
+import django.core.serializers.json
+import importer.validators
+from django.db import migrations, models
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ("importer", "0007_dataimportsession_completed_row_count_history_and_more"),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name="dataimportrow",
+            name="data",
+            field=models.JSONField(
+                blank=True,
+                encoder=django.core.serializers.json.DjangoJSONEncoder,
+                null=True,
+                verbose_name="Data",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="dataimportrow",
+            name="errors",
+            field=models.JSONField(
+                blank=True,
+                encoder=django.core.serializers.json.DjangoJSONEncoder,
+                null=True,
+                verbose_name="Errors",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="dataimportrow",
+            name="row_data",
+            field=models.JSONField(
+                blank=True,
+                encoder=django.core.serializers.json.DjangoJSONEncoder,
+                null=True,
+                verbose_name="Original row data",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="dataimportsession",
+            name="columns",
+            field=models.JSONField(
+                blank=True,
+                encoder=django.core.serializers.json.DjangoJSONEncoder,
+                null=True,
+                verbose_name="Columns",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="dataimportsession",
+            name="field_defaults",
+            field=models.JSONField(
+                blank=True,
+                encoder=django.core.serializers.json.DjangoJSONEncoder,
+                null=True,
+                validators=[importer.validators.validate_field_defaults],
+                verbose_name="Field Defaults",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="dataimportsession",
+            name="field_filters",
+            field=models.JSONField(
+                blank=True,
+                encoder=django.core.serializers.json.DjangoJSONEncoder,
+                null=True,
+                validators=[importer.validators.validate_field_defaults],
+                verbose_name="Field Filters",
+            ),
+        ),
+        migrations.AlterField(
+            model_name="dataimportsession",
+            name="field_overrides",
+            field=models.JSONField(
+                blank=True,
+                encoder=django.core.serializers.json.DjangoJSONEncoder,
+                null=True,
+                validators=[importer.validators.validate_field_defaults],
+                verbose_name="Field Overrides",
+            ),
+        ),
+    ]

src/backend/InvenTree/importer/models.py

@@ -8,6 +8,7 @@ from typing import Optional
 from django.contrib.auth.models import User
 from django.core.exceptions import FieldDoesNotExist
 from django.core.exceptions import ValidationError as DjangoValidationError
+from django.core.serializers.json import DjangoJSONEncoder
 from django.core.validators import FileExtensionValidator
 from django.db import models, transaction
 from django.urls import reverse
@@ -82,7 +83,9 @@ class DataImportSession(models.Model):
         ],
     )
 
-    columns = models.JSONField(blank=True, null=True, verbose_name=_('Columns'))
+    columns = models.JSONField(
+        blank=True, null=True, verbose_name=_('Columns'), encoder=DjangoJSONEncoder
+    )
 
     model_type = models.CharField(
         blank=False,
@@ -107,6 +110,7 @@ class DataImportSession(models.Model):
         null=True,
         verbose_name=_('Field Defaults'),
         validators=[importer.validators.validate_field_defaults],
+        encoder=DjangoJSONEncoder,
     )
 
     field_overrides = models.JSONField(
@@ -114,6 +118,7 @@ class DataImportSession(models.Model):
         null=True,
         verbose_name=_('Field Overrides'),
         validators=[importer.validators.validate_field_defaults],
+        encoder=DjangoJSONEncoder,
     )
 
     field_filters = models.JSONField(
@@ -121,6 +126,7 @@ class DataImportSession(models.Model):
         null=True,
         verbose_name=_('Field Filters'),
         validators=[importer.validators.validate_field_defaults],
+        encoder=DjangoJSONEncoder,
     )
 
     update_records = models.BooleanField(
@@ -668,12 +674,19 @@ class DataImportRow(models.Model):
     row_index = models.PositiveIntegerField(default=0, verbose_name=_('Row Index'))
 
     row_data = models.JSONField(
-        blank=True, null=True, verbose_name=_('Original row data')
+        blank=True,
+        null=True,
+        verbose_name=_('Original row data'),
+        encoder=DjangoJSONEncoder,
     )
 
-    data = models.JSONField(blank=True, null=True, verbose_name=_('Data'))
+    data = models.JSONField(
+        blank=True, null=True, verbose_name=_('Data'), encoder=DjangoJSONEncoder
+    )
 
-    errors = models.JSONField(blank=True, null=True, verbose_name=_('Errors'))
+    errors = models.JSONField(
+        blank=True, null=True, verbose_name=_('Errors'), encoder=DjangoJSONEncoder
+    )
 
     valid = models.BooleanField(default=False, verbose_name=_('Valid'))
 
@@ -762,7 +775,11 @@ class DataImportRow(models.Model):
                         field, value, lookup_field=field_lookup_mapping.get(field)
                     )
                 except DjangoValidationError as exc:
-                    extract_errors[field] = exc.message
+                    # exc.message only exists if the error was raised with a single
+                    # message string - lookup_related_field may also raise with a
+                    # dict (message_dict) or list (message), so use exc.messages,
+                    # which normalizes any construction to a flat list of strings.
+                    extract_errors[field] = '; '.join(exc.messages)
                     continue
 
             # Use the default value, if provided

src/backend/InvenTree/importer/tests.py

@@ -1,5 +1,6 @@
 """Unit tests for the 'importer' app."""
 
+import datetime
 import os
 import threading
 from unittest import mock
@@ -81,6 +82,37 @@ class ImporterTest(ImporterMixin, InvenTreeTestCase):
         # Check that the new companies have been created
         self.assertEqual(n + 12, Company.objects.count())
 
+    def test_row_data_datetime_serialization(self):
+        """Test that row data containing native datetime values can be saved.
+
+        Regression test for a Sentry crash: "Object of type datetime is not JSON
+        serializable when serializing dict item 'COMMENT'". Excel imports (via
+        tablib/openpyxl) return date-formatted cells as native datetime.datetime
+        objects rather than strings. These flow unmodified into row_data, which
+        is then persisted via DataImportRow.objects.bulk_create().
+
+        DataImportRow.row_data / data / errors (and the related JSONFields on
+        DataImportSession) previously had no `encoder=DjangoJSONEncoder`, so
+        Django's JSONField fell back to the plain stdlib json.JSONEncoder, which
+        cannot serialize datetime objects - raising a TypeError on save/bulk_create.
+        """
+        data_file = self.helper_file('companies.csv')
+
+        session = DataImportSession.objects.create(
+            data_file=data_file, model_type='company'
+        )
+
+        row = DataImportRow(
+            session=session,
+            row_index=0,
+            row_data={'COMMENT': datetime.datetime(2024, 5, 1, 12, 30)},
+        )
+
+        # This must not raise: TypeError: Object of type datetime is not JSON serializable
+        DataImportRow.objects.bulk_create([row])
+        row = DataImportRow.objects.get(session=session, row_index=0)
+        self.assertEqual(row.row_data['COMMENT'], '2024-05-01T12:30:00')
+
     def test_import_header_whitespace(self):
         """Test that column headers with leading/trailing whitespace are handled correctly.
 
@@ -338,6 +370,45 @@ class ImporterTest(ImporterMixin, InvenTreeTestCase):
         result = row.lookup_related_field('part', 'AMBIG-001', lookup_field='name')
         self.assertNotEqual(result, part_a.pk)
 
+    def test_extract_data_related_field_validation_error(self):
+        """Test that extract_data() handles a dict-constructed ValidationError.
+
+        Regression test: django.core.exceptions.ValidationError only exposes a
+        `.message` attribute when it was raised with a single message string.
+        lookup_related_field can also raise with a dict (e.g. "no related model
+        found for field") or a list, in which case `.message` does not exist and
+        accessing it raises: AttributeError: 'ValidationError' object has no
+        attribute 'message'. extract_data() must use `.messages` instead, which
+        normalizes any construction to a flat list of strings.
+        """
+        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'
+        )
+
+        row = DataImportRow(session=session, row_data={'Website': 'foo'})
+
+        field_mapping = {'part': 'Website'}
+        available_fields = {'part': {'type': 'related field'}}
+
+        with mock.patch.object(
+            DataImportRow,
+            'lookup_related_field',
+            side_effect=DjangoValidationError({
+                'session': 'No related model found for field: part'
+            }),
+        ):
+            # Must not raise: AttributeError: 'ValidationError' object has no attribute 'message'
+            row.extract_data(
+                field_mapping=field_mapping,
+                available_fields=available_fields,
+                commit=False,
+            )
+
+        self.assertEqual(row.errors, {'part': 'No related model found for field: part'})
+
     def test_lookup_field_validation(self):
         """Test that DataImportColumnMap.clean() validates the lookup_field value."""
         from django.core.exceptions import ValidationError as DjangoValidationError