Merge pull request django-import-export#398 from sgarcialaguna/master

Reset SQL sequences when new objects are imported

import_export/resources.py

@@ -10,7 +10,8 @@
 
 from django import VERSION
 from django.conf import settings
-from django.db import transaction
+from django.core.management.color import no_style
+from django.db import connections, transaction, DEFAULT_DB_ALIAS
 from django.db.models.fields import FieldDoesNotExist
 from django.db.models.query import QuerySet
 from django.db.transaction import TransactionManagementError
@@ -397,6 +398,16 @@ def import_data(self, dataset, dry_run=False, raise_errors=False,
                     self._meta.report_skipped):
                 result.rows.append(row_result)
 
+        # Reset the SQL sequences when new objects are imported
+        # Adapted from django's loaddata
+        if not dry_run and any(r.import_type == RowResult.IMPORT_TYPE_NEW for r in result.rows):
+            connection = connections[DEFAULT_DB_ALIAS]
+            sequence_sql = connection.ops.sequence_reset_sql(no_style(), [self.Meta.model])
+            if sequence_sql:
+                with connection.cursor() as cursor:
+                    for line in sequence_sql:
+                        cursor.execute(line)
+
         if use_transactions:
             if dry_run or result.has_errors():
                 savepoint_rollback(sp1)

requirements/dev.txt

@@ -1,3 +1,4 @@
 -r base.txt
 sphinx
 mysql-python
+psycopg2==2.6.1

tests/core/tests/resources_tests.py

@@ -4,9 +4,11 @@
 from copy import deepcopy
 from datetime import date
 from decimal import Decimal
-from unittest import skip
+from unittest import skip, skipUnless
 
+from django.conf import settings
 from django.contrib.auth.models import User
+from django.db import IntegrityError
 from django.db.models import Count
 from django.db.models.fields import FieldDoesNotExist
 from django.test import TestCase, TransactionTestCase, skipUnlessDBFeature
@@ -668,3 +670,22 @@ def test_create(self):
         BookResource = resources.modelresource_factory(Book)
         self.assertIn('id', BookResource.fields)
         self.assertEqual(BookResource._meta.model, Book)
+
+
+@skipUnless(
+    'postgresql' in settings.DATABASES['default']['ENGINE'],
+    'Run only against Postgres')
+class PostgresTests(TransactionTestCase):
+    # Make sure to start the sequences back at 1
+    reset_sequences = True
+
+    def test_create_object_after_importing_dataset_with_id(self):
+        dataset = tablib.Dataset(headers=['id', 'name'])
+        dataset.append([1, 'Some book'])
+        resource = BookResource()
+        result = resource.import_data(dataset)
+        self.assertFalse(result.has_errors())
+        try:
+            Book.objects.create(name='Some other book')
+        except IntegrityError:
+            self.fail('IntegrityError was raised.')

tests/settings.py

@@ -56,6 +56,18 @@
             }
         }
     }
+elif os.environ.get('IMPORT_EXPORT_TEST_TYPE') == 'postgres':
+    IMPORT_EXPORT_USE_TRANSACTIONS = True
+    DATABASES = {
+        'default': {
+            'ENGINE': 'django.db.backends.postgresql',
+            'NAME': 'import_export',
+            'USER': os.environ.get('IMPORT_EXPORT_POSTGRESQL_USER'),
+            'PASSWORD': os.environ.get('IMPORT_EXPORT_POSTGRESQL_PASSWORD'),
+            'HOST': 'localhost',
+            'PORT': 5432
+        }
+    }
 else:
     DATABASES = {
         'default': {