fix the migration history and provide a script to update existing paperless instances to the new version

src/documents/migrations/1000_update_paperless.py

@@ -0,0 +1,57 @@
+# Generated by Django 3.1.2 on 2020-10-29 14:29
+import os
+
+from django.db import migrations
+
+from django.conf import settings
+
+
+def make_index(apps, schema_editor):
+    Document = apps.get_model("documents", "Document")
+    documents = Document.objects.all()
+    print()
+    try:
+        print("  --> Creating document index...")
+        from whoosh.writing import AsyncWriter
+        from documents import index
+        ix = index.open_index(recreate=True)
+        with AsyncWriter(ix) as writer:
+            for document in documents:
+                index.update_document(writer, document)
+    except ImportError:
+        # index may not be relevant anymore
+        print("  --> Cannot create document index.")
+
+
+def restore_filenames(apps, schema_editor):
+    Document = apps.get_model("documents", "Document")
+    for doc in Document.objects.all():
+        file_name = "{:07}.{}".format(doc.pk, doc.file_type)
+        if doc.storage_type == "gpg":
+            file_name += ".gpg"
+
+        if not doc.filename == file_name:
+            try:
+                print("file was renamed, restoring {} to {}".format(doc.filename, file_name))
+                os.rename(os.path.join(settings.ORIGINALS_DIR, doc.filename),
+                          os.path.join(settings.ORIGINALS_DIR, file_name))
+            except PermissionError:
+                pass
+            except FileNotFoundError:
+                pass
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('documents', '0023_document_current_filename'),
+    ]
+
+    operations = [
+        migrations.RunPython(make_index, migrations.RunPython.noop),
+        migrations.RunPython(restore_filenames),
+        migrations.RemoveField(
+            model_name='document',
+            name='filename',
+        ),
+    ]