FIX: Make lists and dicts hashable

pyproject.toml

@@ -33,6 +33,7 @@ dependencies = [
   "num2words >=0.5.5",
   "click >=8.0",
   "universal_pathlib >=0.2.2",
+  "frozendict >=2",
 ]
 dynamic = ["version"]
 

src/bids/layout/layout.py

@@ -16,7 +16,7 @@
 from sqlalchemy.sql.expression import cast
 from bids_validator import BIDSValidator
 
-from ..utils import listify, natural_sort
+from ..utils import listify, natural_sort, hashablefy
 from ..external import inflect
 from ..exceptions import (
     BIDSDerivativesValidationError,
@@ -645,6 +645,13 @@
             A list of BIDSFiles (default) or strings (see return_type).
         """
 
+        if (
+            not return_type.startswith(("obj", "file"))
+            and return_type not in ("id", "dir")
+        ):
+            raise ValueError(f"Invalid return_type <{return_type}> specified (must be one "
+                             "of 'object', 'file', 'filename', 'id', or 'dir').")
+
         if absolute_paths is False:
             absolute_path_deprecation_warning()
 
@@ -691,6 +698,9 @@
                 message = "Valid targets are: {}".format(potential)
             raise TargetError(("Unknown target '{}'. " + message)
                              .format(target))
+        elif target is None and return_type in ['id', 'dir']:
+            raise TargetError('If return_type is "id" or "dir", a valid '
+                              'target entity must also be specified.')
 
         results = []
         for l in layouts:
@@ -718,18 +728,22 @@
 
         if return_type.startswith('file'):
             results = natural_sort([f.path for f in results])
-
         elif return_type in ['id', 'dir']:
             if target is None:
                 raise TargetError('If return_type is "id" or "dir", a valid '
                                  'target entity must also be specified.')
 
+            metadata = target not in self.get_entities(metadata=False)
+
             if return_type == 'id':
+                ent_iter = (
+                    hashablefy(res.get_entities(metadata=metadata))
+                    for res in results if target in res.entities
+                )
                 results = list(dict.fromkeys(
-                    res.entities[target] for res in results
-                    if target in res.entities and isinstance(res.entities[target], Hashable)
+                    ents[target] for ents in ent_iter if target in ents
                 ))
-
+                results = natural_sort(list(set(results)))
             elif return_type == 'dir':
                 template = entities[target].directory
                 if template is None:
@@ -752,12 +766,7 @@
                     for f in results
                     if re.search(template, f._dirname.as_posix())
                 ]
-
                 results = natural_sort(list(set(matches)))
-
-            else:
-                raise ValueError("Invalid return_type specified (must be one "
-                                 "of 'tuple', 'filename', 'id', or 'dir'.")
         else:
             results = natural_sort(results, 'path')
 

src/bids/layout/tests/test_layout.py

@@ -776,6 +776,27 @@ def test_get_tr(layout_7t_trt):
     assert sum([t in tr for t in [3.0, 4.0]]) == 2
 
 
+def test_get_nonhashable_metadata(layout_ds117):
+    """Test nonhashable metadata values (#683)."""
+    assert layout_ds117.get_IntendedFor(subject=['01'])[0] == (
+       "ses-mri/func/sub-01_ses-mri_task-facerecognition_run-01_bold.nii.gz",
+       "ses-mri/func/sub-01_ses-mri_task-facerecognition_run-02_bold.nii.gz",
+       "ses-mri/func/sub-01_ses-mri_task-facerecognition_run-03_bold.nii.gz",
+       "ses-mri/func/sub-01_ses-mri_task-facerecognition_run-04_bold.nii.gz",
+       "ses-mri/func/sub-01_ses-mri_task-facerecognition_run-05_bold.nii.gz",
+       "ses-mri/func/sub-01_ses-mri_task-facerecognition_run-06_bold.nii.gz",
+       "ses-mri/func/sub-01_ses-mri_task-facerecognition_run-07_bold.nii.gz",
+       "ses-mri/func/sub-01_ses-mri_task-facerecognition_run-08_bold.nii.gz",
+       "ses-mri/func/sub-01_ses-mri_task-facerecognition_run-09_bold.nii.gz",
+    )
+
+    landmarks = layout_ds117.get_AnatomicalLandmarkCoordinates(subject=['01'])[0]
+    assert landmarks["Nasion"] == (43, 111, 95)
+    assert landmarks["LPA"] == (140, 74, 16)
+    assert landmarks["RPA"] == (143, 74, 173)
+
+
+
 def test_to_df(layout_ds117):
     # Only filename entities
     df = layout_ds117.to_df()

src/bids/utils.py

@@ -2,15 +2,36 @@
 
 import re
 import os
+from pathlib import Path
+from frozendict import frozendict as _frozendict
 from upath import UPath as Path
 
 
+# Monkeypatch to print out frozendicts *as if* they were dictionaries.
+class frozendict(_frozendict):
+    """A hashable dictionary type."""
+
+    def __repr__(self):
+        """Override frozendict representation."""
+        return repr({k: v for k, v in self.items()})
+
+
 def listify(obj):
     ''' Wraps all non-list or tuple objects in a list; provides a simple way
     to accept flexible arguments. '''
     return obj if isinstance(obj, (list, tuple, type(None))) else [obj]
 
 
+def hashablefy(obj):
+    ''' Make dictionaries and lists hashable or raise. '''
+    if isinstance(obj, list):
+        return tuple([hashablefy(o) for o in obj])
+
+    if isinstance(obj, dict):
+        return frozendict({k: hashablefy(v) for k, v in obj.items()})
+    return obj
+
+
 def matches_entities(obj, entities, strict=False):
     ''' Checks whether an object's entities match the input. '''
     if strict and set(obj.entities.keys()) != set(entities.keys()):