Add Datastore._set_trust_mode

Method makes it easier for quantum backed butler and tests to change
the flag.

python/lsst/daf/butler/_quantum_backed.py

@@ -357,9 +357,7 @@ def _initialize(
         # TODO: We need to inform `Datastore` here that it needs to support
         # predictive reads; This only really works for file datastore but
         # we need to try everything in case there is a chained datastore.
-        for this_datastore in getattr(datastore, "datastores", [datastore]):
-            if hasattr(this_datastore, "trustGetRequest"):
-                this_datastore.trustGetRequest = True
+        datastore._set_trust_mode(True)
 
         if datastore_records is not None:
             datastore.import_records(datastore_records)

python/lsst/daf/butler/datastore/_datastore.py

@@ -476,6 +476,24 @@ def transaction(self) -> Iterator[DatastoreTransaction]:
             self._transaction.commit()
         self._transaction = self._transaction.parent
 
+    def _set_trust_mode(self, mode: bool) -> None:
+        """Set the trust mode for this datastore.
+
+        Parameters
+        ----------
+        mode : `bool`
+            If `True`, get requests will be attempted even if the datastore
+            does not know about the dataset.
+
+        Notes
+        -----
+        This is a private method to indicate that trust mode might be a
+        transitory property that we do not want to make fully public. For now
+        only a `~lsst.daf.butler.datastores.FileDatastore` understands this
+        concept. By default this method does nothing.
+        """
+        return
+
     @abstractmethod
     def knows(self, ref: DatasetRef) -> bool:
         """Check if the dataset is known to the datastore.

python/lsst/daf/butler/datastores/chainedDatastore.py

@@ -264,6 +264,10 @@ def __str__(self) -> str:
         chainName = ", ".join(str(ds) for ds in self.datastores)
         return chainName
 
+    def _set_trust_mode(self, mode: bool) -> None:
+        for datastore in self.datastores:
+            datastore._set_trust_mode(mode)
+
     def knows(self, ref: DatasetRef) -> bool:
         """Check if the dataset is known to any of the datastores.
 

python/lsst/daf/butler/datastores/fileDatastore.py

@@ -359,6 +359,9 @@ def roots(self) -> dict[str, ResourcePath | None]:
         # Docstring inherited.
         return {self.name: self.root}
 
+    def _set_trust_mode(self, mode: bool) -> None:
+        self.trustGetRequest = mode
+
     def _artifact_exists(self, location: Location) -> bool:
         """Check that an artifact exists in this datastore at the specified
         location.

tests/test_butler.py

@@ -107,7 +107,7 @@ def mock_s3(*args: Any, **kwargs: Any) -> Any:  # type: ignore[no-untyped-def]
 if TYPE_CHECKING:
     import types
 
-    from lsst.daf.butler import Datastore, DimensionGroup, Registry, StorageClass
+    from lsst.daf.butler import DimensionGroup, Registry, StorageClass
 
 TESTDIR = os.path.abspath(os.path.dirname(__file__))
 
@@ -2114,12 +2114,6 @@ def testTransferUuidToUuid(self) -> None:
         self.create_butlers()
         self.assertButlerTransfers()
 
-    def _enable_trust(self, datastore: Datastore) -> None:
-        datastores = getattr(datastore, "datastores", [datastore])
-        for this_datastore in datastores:
-            if hasattr(this_datastore, "trustGetRequest"):
-                this_datastore.trustGetRequest = True
-
     def testTransferMissing(self) -> None:
         """Test transfers where datastore records are missing.
 
@@ -2128,7 +2122,7 @@ def testTransferMissing(self) -> None:
         self.create_butlers()
 
         # Configure the source butler to allow trust.
-        self._enable_trust(self.source_butler._datastore)
+        self.source_butler._datastore._set_trust_mode(True)
 
         self.assertButlerTransfers(purge=True)
 
@@ -2140,7 +2134,7 @@ def testTransferMissingDisassembly(self) -> None:
         self.create_butlers()
 
         # Configure the source butler to allow trust.
-        self._enable_trust(self.source_butler._datastore)
+        self.source_butler._datastore._set_trust_mode(True)
 
         # Test disassembly.
         self.assertButlerTransfers(purge=True, storageClassName="StructuredComposite")