Add management command to recover deleted attachments

onadata/apps/logger/management/commands/recover_deleted_attachments.py

@@ -0,0 +1,40 @@
+from django.core.management.base import BaseCommand
+
+from onadata.apps.logger.models import Instance
+
+
+def recover_soft_deleted_attachments(self, form_id, stdout=None):
+    """
+    Recovers attachments that were accidentally soft-deleted
+
+    :param: (str) form_id: Unique identifier for a XForm object
+    :param: (sys.stdout) stdout: Python standard output. Default: None
+    """
+    instances = Instance.objects.filter(
+            xform__id=form_id, deleted_at__isnull=True)
+    for instance in instances:
+        expected_no_of_attachments = instance.get_expected_media()
+        if not instance.attachments.filter(
+                deleted_at__isnull=True) == expected_no_of_attachments:
+            attachments_to_recover = instance.attachments.filter(
+                    deleted_at__isnull=False,
+                    name__in=instance.get_expected_media())
+            for attachment in attachments_to_recover:
+                attachment.deleted_at = None
+                attachment.deleted_by = None
+                attachment.save()
+
+                if stdout:
+                    stdout.write(
+                        f'Recovered {attachment.name} ID: {attachment.id}')
+
+
+class Command(BaseCommand):
+    help = 'Restore wrongly deleted attachments'
+
+    def add_arguments(self, parser):
+        parser.add_argument('-f', '--form', dest='form_id', type=int)
+
+    def handle(self, *args, **options):
+        form_id = options.get('form_id')
+        recover_soft_deleted_attachments(self, form_id, self.stdout)