add migration to fix null characters in document contents

src/documents/migrations/1015_remove_null_characters.py

@@ -0,0 +1,29 @@
+# Generated by Django 3.1.7 on 2021-04-04 18:28
+import logging
+
+from django.db import migrations
+
+
+logger = logging.getLogger("paperless.migrations")
+
+
+def remove_null_characters(apps, schema_editor):
+    Document = apps.get_model('documents', 'Document')
+
+    for doc in Document.objects.all():
+        content: str = doc.content
+        if '\0' in content:
+            logger.info(f"Removing null characters from document {doc}...")
+            doc.content = content.replace('\0', ' ')
+            doc.save()
+
+
+class Migration(migrations.Migration):
+
+    dependencies = [
+        ('documents', '1014_auto_20210228_1614'),
+    ]
+
+    operations = [
+        migrations.RunPython(remove_null_characters, migrations.RunPython.noop)
+    ]

src/documents/tests/test_migration_remove_null_characters.py

@@ -0,0 +1,15 @@
+from documents.tests.utils import DirectoriesMixin, TestMigrations
+
+
+class TestMigrateNullCharacters(DirectoriesMixin, TestMigrations):
+
+    migrate_from = '1014_auto_20210228_1614'
+    migrate_to = '1015_remove_null_characters'
+
+    def setUpBeforeMigration(self, apps):
+        Document = apps.get_model("documents", "Document")
+        self.doc = Document.objects.create(content="aaa\0bbb")
+
+    def testMimeTypesMigrated(self):
+        Document = self.apps.get_model('documents', 'Document')
+        self.assertNotIn("\0", Document.objects.get(id=self.doc.id).content)