Merge pull request #425 from lsst/tickets/DM-26658

DM-26658: Use FormatterV2 for configs

python/lsst/pipe/base/formatters/pexConfig.py

@@ -29,55 +29,26 @@
 
 __all__ = ("PexConfigFormatter",)
 
-import os.path
-from typing import Any
+from typing import Any, BinaryIO
 
-from lsst.daf.butler.formatters.file import FileFormatter
+from lsst.daf.butler import FormatterV2
 from lsst.pex.config import Config
+from lsst.resources import ResourceHandleProtocol, ResourcePath
 
 
-class PexConfigFormatter(FileFormatter):
+class PexConfigFormatter(FormatterV2):
     """Formatter implementation for reading and writing
     `lsst.pex.config.Config` instances.
     """
 
-    extension = ".py"
-
-    def _readFile(self, path: str, pytype: type[Any] | None = None) -> Any:
-        """Read a pex.config.Config instance from the given file.
-
-        Parameters
-        ----------
-        path : `str`
-            Path to use to open the file.
-        pytype : `type`, optional
-            Class to use to read the config file.
-
-        Returns
-        -------
-        data : `lsst.pex.config.Config`
-            Instance of class ``pytype`` read from config file. `None`
-            if the file could not be opened.
-        """
-        if not os.path.exists(path):
-            return None
+    default_extension = ".py"
+    can_read_from_stream = True
 
+    def read_from_stream(
+        self, stream: BinaryIO | ResourceHandleProtocol, component: str | None = None, expected_size: int = -1
+    ) -> Any:
         # Automatically determine the Config class from the serialized form
-        with open(path, "r") as fd:
-            config_py = fd.read()
-        return Config._fromPython(config_py)
-
-    def _writeFile(self, inMemoryDataset: Any) -> None:
-        """Write the in memory dataset to file on disk.
-
-        Parameters
-        ----------
-        inMemoryDataset : `object`
-            Object to serialize.
+        return Config._fromPython(stream.read().decode())
 
-        Raises
-        ------
-        Exception
-            The file could not be written.
-        """
-        inMemoryDataset.save(self.fileDescriptor.location.path)
+    def write_local_file(self, in_memory_dataset: Any, uri: ResourcePath) -> None:
+        in_memory_dataset.save(uri.path)

python/lsst/pipe/base/tests/mocks/_storage_class.py

@@ -51,6 +51,7 @@
     DatasetType,
     Formatter,
     FormatterFactory,
+    FormatterV2,
     LookupKey,
     SerializedDatasetType,
     StorageClass,
@@ -606,7 +607,7 @@ def new_get_storage_class(self: StorageClassFactory, storageClassName: str) -> S
 
     def new_get_formatter_class_with_match(
         self: FormatterFactory, entity: Any
-    ) -> tuple[LookupKey, type[Formatter], dict[str, Any]]:
+    ) -> tuple[LookupKey, type[Formatter | FormatterV2], dict[str, Any]]:
         try:
             return original_get_formatter_class_with_match(self, entity)
         except KeyError:
@@ -629,7 +630,7 @@ def new_get_formatter_class_with_match(
 
     def new_get_formatter_with_match(
         self: FormatterFactory, entity: Any, *args: Any, **kwargs: Any
-    ) -> tuple[LookupKey, Formatter]:
+    ) -> tuple[LookupKey, Formatter | FormatterV2]:
         try:
             return original_get_formatter_with_match(self, entity, *args, **kwargs)
         except KeyError: