Create _serializers.py

Author: schloerke

shiny/bookmark/_serializers.py

@@ -0,0 +1,49 @@
+from pathlib import Path
+from shutil import copyfile
+from typing import Any, TypeVar
+
+from typing_extensions import TypeIs
+
+
+class Unserializable: ...
+
+
+T = TypeVar("T")
+
+
+def is_unserializable(x: Any) -> TypeIs[Unserializable]:
+    return isinstance(x, Unserializable)
+
+
+async def serializer_unserializable(
+    value: Any = None, state_dir: Path | None = None
+) -> Unserializable:
+    return Unserializable()
+
+
+async def serializer_default(value: T, state_dir: Path | None) -> T:
+    return value
+
+
+# TODO-barret; Integrate
+def serializer_file_input(
+    value: Any,
+    state_dir: Path | None,
+) -> Any | Unserializable:
+    if state_dir is None:
+        return Unserializable()
+
+    # TODO: barret; Double check this logic!
+
+    # `value` is a data frame. When persisting files, we need to copy the file to
+    # the persistent dir and then strip the original path before saving.
+    datapath = Path(value["datapath"])
+    new_paths = state_dir / datapath.name
+
+    if new_paths.exists():
+        new_paths.unlink()
+    copyfile(datapath, new_paths)
+
+    value["datapath"] = new_paths.name
+
+    return value