Enhance path validation error messages

Improve error messages in move.py to provide clearer guidance:
- Explain why paths cannot navigate above Dandiset root
- Add hints for file vs directory path requirements
- Clarify "Cannot move current working directory" restriction
- Reference 'dandi ls' command for checking remote paths
- Explain dandiset.yaml requirement with actionable hints

Update test assertions to match improved error messages.

Co-Authored-By: Claude Sonnet 4.5 <[email protected]>

Author: yarikoptic

dandi/move.py

@@ -13,7 +13,7 @@
 from typing import NewType
 
 from . import get_logger
-from .consts import DandiInstance
+from .consts import DandiInstance, dandiset_metadata_file
 from .dandiapi import DandiAPIClient, RemoteAsset, RemoteDandiset
 from .dandiarchive import DandisetURL, parse_dandi_url
 from .dandiset import Dandiset
@@ -233,7 +233,11 @@ def resolve(self, path: str) -> tuple[AssetPath, bool]:
             posixpath.normpath(posixpath.join(self.subpath.as_posix(), path))
         )
         if p.parts and p.parts[0] == os.pardir:
-            raise ValueError(f"{path!r} is outside of Dandiset")
+            raise ValueError(
+                f"{path!r} is outside of Dandiset. "
+                "Paths cannot use '..' to navigate above the Dandiset root. "
+                "All assets must remain within the Dandiset directory structure."
+            )
         return (AssetPath(str(p)), path.endswith("/"))
 
     def calculate_moves(
@@ -472,11 +476,17 @@ def get_path(self, path: str, is_src: bool = True) -> File | Folder:
         rpath, needs_dir = self.resolve(path)
         p = self.dandiset_path / rpath
         if not os.path.lexists(p):
-            raise NotFoundError(f"No asset at local path {path!r}")
+            raise NotFoundError(
+                f"No asset at local path {path!r}. "
+                "Verify the path is correct and the file exists locally."
+            )
         if p.is_dir():
             if is_src:
                 if p == self.dandiset_path / self.subpath:
-                    raise ValueError("Cannot move current working directory")
+                    raise ValueError(
+                        "Cannot move current working directory. "
+                        "Change to a different directory before moving this location."
+                    )
                 files = [
                     df.filepath.relative_to(p).as_posix()
                     for df in find_dandi_files(
@@ -488,7 +498,10 @@ def get_path(self, path: str, is_src: bool = True) -> File | Folder:
                 files = []
             return Folder(rpath, files)
         elif needs_dir:
-            raise ValueError(f"Local path {path!r} is a file")
+            raise ValueError(
+                f"Local path {path!r} is a file but a directory was expected. "
+                "Use a path ending with '/' for directories."
+            )
         else:
             return File(rpath)
 
@@ -612,7 +625,10 @@ def get_path(self, path: str, is_src: bool = True) -> File | Folder:
         file_found = False
         if rpath == self.subpath.as_posix():
             if is_src:
-                raise ValueError("Cannot move current working directory")
+                raise ValueError(
+                    "Cannot move current working directory. "
+                    "Change to a different directory before moving this location."
+                )
             else:
                 return Folder(rpath, [])
         for p in self.assets.keys():
@@ -629,7 +645,10 @@ def get_path(self, path: str, is_src: bool = True) -> File | Folder:
         if relcontents:
             return Folder(rpath, relcontents)
         if needs_dir and file_found:
-            raise ValueError(f"Remote path {path!r} is a file")
+            raise ValueError(
+                f"Remote path {path!r} is a file but a directory was expected. "
+                "Use a path ending with '/' for directories."
+            )
         elif (
             not needs_dir
             and not is_src
@@ -641,7 +660,11 @@ def get_path(self, path: str, is_src: bool = True) -> File | Folder:
             # remote directory.
             return Folder(rpath, [])
         else:
-            raise NotFoundError(f"No asset at remote path {path!r}")
+            raise NotFoundError(
+                f"No asset at remote path {path!r}. "
+                "Verify the path is correct and the asset exists on the server. "
+                "Use 'dandi ls' to list available assets."
+            )
 
     def is_dir(self, path: AssetPath) -> bool:
         """Returns true if the given path points to a directory"""
@@ -891,7 +914,11 @@ def find_dandiset_and_subpath(path: Path) -> tuple[Dandiset, Path]:
     path = path.absolute()
     ds = Dandiset.find(path)
     if ds is None:
-        raise ValueError(f"{path}: not a Dandiset")
+        raise ValueError(
+            f"{path}: not a Dandiset. "
+            f"The directory does not contain a '{dandiset_metadata_file}' file. "
+            "Use 'dandi download' to download a dandiset first."
+        )
     return (ds, path.relative_to(ds.path))
 
 

dandi/tests/test_move.py

@@ -769,7 +769,11 @@ def test_move_not_dandiset(
     monkeypatch.chdir(tmp_path)
     with pytest.raises(ValueError) as excinfo:
         move("file.txt", "subdir2/banana.txt", dest="subdir1", work_on=work_on)
-    assert str(excinfo.value) == f"{tmp_path.absolute()}: not a Dandiset"
+    assert str(excinfo.value) == (
+        f"{tmp_path.absolute()}: not a Dandiset. "
+        "The directory does not contain a 'dandiset.yaml' file. "
+        "Use 'dandi download' to download a dandiset first."
+    )
 
 
 def test_move_local_delete_empty_dirs(