Fix: Lazy-initialize storage class to prevent unwanted migration gene…

…ration

import_export_celery/fields.py

@@ -3,11 +3,15 @@
 from django.db import models
 
 
+def lazy_initialize_storage_class():
+    # If the user has specified a custom storage backend, use it.
+    if getattr(settings, "IMPORT_EXPORT_CELERY_STORAGE", None):
+        storage_class = get_storage_class(settings.IMPORT_EXPORT_CELERY_STORAGE)
+        return storage_class()
+    return None
+
+
 class ImportExportFileField(models.FileField):
     def __init__(self, *args, **kwargs):
-        # If the user has specified a custom storage backend, use it.
-        if getattr(settings, "IMPORT_EXPORT_CELERY_STORAGE", None):
-            storage_class = get_storage_class(settings.IMPORT_EXPORT_CELERY_STORAGE)
-            kwargs["storage"] = storage_class()
-
+        kwargs["storage"] = lazy_initialize_storage_class
         super().__init__(*args, **kwargs)

import_export_celery/migrations/0010_auto_20231013_0904.py

@@ -0,0 +1,29 @@
+# Generated by Django 3.2.18 on 2023-10-13 09:04
+
+from django.db import migrations
+import import_export_celery.fields
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('import_export_celery', '0009_alter_exportjob_options_alter_importjob_options_and_more'),
+    ]
+
+    operations = [
+        migrations.AlterField(
+            model_name='exportjob',
+            name='file',
+            field=import_export_celery.fields.ImportExportFileField(max_length=255, storage=import_export_celery.fields.lazy_initialize_storage_class, upload_to='django-import-export-celery-export-jobs', verbose_name='exported file'),
+        ),
+        migrations.AlterField(
+            model_name='importjob',
+            name='change_summary',
+            field=import_export_celery.fields.ImportExportFileField(blank=True, null=True, storage=import_export_celery.fields.lazy_initialize_storage_class, upload_to='django-import-export-celery-import-change-summaries', verbose_name='Summary of changes made by this import'),
+        ),
+        migrations.AlterField(
+            model_name='importjob',
+            name='file',
+            field=import_export_celery.fields.ImportExportFileField(max_length=255, storage=import_export_celery.fields.lazy_initialize_storage_class, upload_to='django-import-export-celery-import-jobs', verbose_name='File to be imported'),
+        ),
+    ]