Implement a no_delete flag

See: https://github.com/pimutils/vdirsyncer/pull/1090

AUTHORS.rst

@@ -7,6 +7,7 @@ In alphabetical order:
 - Christian Geier
 - Clément Mondon
 - Corey Hinshaw
+- Kai Herlemann
 - Hugo Osvaldo Barrera
 - Julian Mehne
 - Malte Kiefer

CHANGELOG.rst

@@ -12,6 +12,7 @@ may want to subscribe to `GitHub's tag feed
 Version 0.19.3
 ==============
 
+- Added a no_delete option to the storage configuration. :gh:`1090`
 - Fix crash when running ``vdirsyncer repair`` on a collection. :gh:`1019`
 - Add an option to request vCard v4.0.  :gh:`1066`
 

tests/system/utils/test_main.py

@@ -22,7 +22,7 @@ def test_get_storage_init_args():
     from vdirsyncer.storage.memory import MemoryStorage
 
     all, required = utils.get_storage_init_args(MemoryStorage)
-    assert all == {"fileext", "collection", "read_only", "instance_name"}
+    assert all == {"fileext", "collection", "read_only", "instance_name", "no_delete"}
     assert not required
 
 

vdirsyncer/storage/base.py

@@ -67,6 +67,10 @@ class Storage(metaclass=StorageMeta):
     # The machine-readable name of this collection.
     collection = None
 
+    #A value of False means storage does not support delete requests. A
+    #value of True mean the storage supports it.
+    no_delete = False
+
     # A value of True means the storage does not support write-methods such as
     # upload, update and delete.  A value of False means the storage does
     # support those methods.
@@ -75,13 +79,19 @@ class Storage(metaclass=StorageMeta):
     # The attribute values to show in the representation of the storage.
     _repr_attributes: list[str] = []
 
-    def __init__(self, instance_name=None, read_only=None, collection=None):
+    def __init__(self, instance_name=None, read_only=None, no_delete=None, collection=None):
         if read_only is None:
             read_only = self.read_only
         if self.read_only and not read_only:
             raise exceptions.UserError("This storage can only be read-only.")
         self.read_only = bool(read_only)
 
+        if no_delete is None:
+            no_delete = self.no_delete
+        if self.no_delete and not no_delete:
+            raise exceptions.UserError("Nothing can be deleted in this storage.")
+        self.no_delete = bool(no_delete)
+
         if collection and instance_name:
             instance_name = f"{instance_name}/{collection}"
         self.instance_name = instance_name

vdirsyncer/sync/__init__.py

@@ -243,7 +243,9 @@ class Delete(Action):
 
     async def _run_impl(self, a, b):
         meta = self.dest.status.get_new(self.ident)
-        if not self.dest.storage.read_only:
+        if self.dest.storage.read_only or self.dest.storage.no_delete:
+            sync_logger.debug(f"Skipping deletion of item {self.ident} from {self.dest.storage}")
+        else:
             sync_logger.info(f"Deleting item {self.ident} from {self.dest.storage}")
             await self.dest.storage.delete(meta.href, meta.etag)