[FIX] Permitting desc for channels and events (#2043)

Co-authored-by: Christopher J. Markiewicz <[email protected]>

src/schema/rules/files/deriv/preprocessed_data.yaml

@@ -69,6 +69,54 @@ beh_noncontinuous_common:
     space: optional
     description: optional
 
+channels_channels_common:
+  $ref: rules.files.raw.channels.channels
+  entities:
+    $ref: rules.files.raw.channels.channels.entities
+    description: optional
+
+channels_channels__meg_common:
+  $ref: rules.files.raw.channels.channels__meg
+  entities:
+    $ref: rules.files.raw.channels.channels__meg.entities
+    description: optional
+
+channels_channels__motion_common:
+  $ref: rules.files.raw.channels.channels__motion
+  entities:
+    $ref: rules.files.raw.channels.channels__motion.entities
+    description: optional
+
+channels_coordsystem_common:
+  $ref: rules.files.raw.channels.coordsystem
+  entities:
+    $ref: rules.files.raw.channels.coordsystem.entities
+    description: optional
+
+channels_coordsystem__eeg_common:
+  $ref: rules.files.raw.channels.coordsystem__eeg
+  entities:
+    $ref: rules.files.raw.channels.coordsystem__eeg.entities
+    description: optional
+
+channels_electrodes_common:
+  $ref: rules.files.raw.channels.electrodes
+  entities:
+    $ref: rules.files.raw.channels.electrodes.entities
+    description: optional
+
+channels_electrodes__meg_common:
+  $ref: rules.files.raw.channels.electrodes__meg
+  entities:
+    $ref: rules.files.raw.channels.electrodes__meg.entities
+    description: optional
+
+channels_electrodes_optodes_common:
+  $ref: rules.files.raw.channels.optodes
+  entities:
+    $ref: rules.files.raw.channels.optodes.entities
+    description: optional
+
 dwi_dwi_common:
   $ref: rules.files.raw.dwi.dwi
   entities:
@@ -229,3 +277,9 @@ pet_blood_common:
     $ref: rules.files.raw.pet.blood.entities
     space: optional
     description: optional
+
+task_events_common:
+  $ref: rules.files.raw.task.events
+  entities:
+    $ref: rules.files.raw.task.events.entities
+    description: optional

tools/schemacode/src/bidsschematools/schema.py

@@ -90,6 +90,21 @@ def _find(obj, predicate):
         yield from _find(item, predicate)
 
 
+def _dereference(namespace, base_schema):
+    # In-place, recursively dereference objects
+    # This allows a referenced object to itself contain a reference
+    # A dependency graph could be constructed, but would likely be slower
+    # to build than to duplicate a couple dereferences
+    for struct in _find(namespace, lambda obj: "$ref" in obj):
+        target = base_schema.get(struct["$ref"])
+        if target is None:
+            raise ValueError(f"Reference {struct['$ref']} not found in schema.")
+        if isinstance(target, Mapping):
+            struct.pop("$ref")
+            _dereference(target, base_schema)
+            struct.update({**target, **struct})
+
+
 def dereference(namespace, inplace=True):
     """Replace references in namespace with the contents of the referred object.
 
@@ -109,11 +124,7 @@ def dereference(namespace, inplace=True):
     if not inplace:
         namespace = deepcopy(namespace)
 
-    for struct in _find(namespace, lambda obj: "$ref" in obj):
-        target = namespace.get(struct["$ref"])
-        if isinstance(target, Mapping):
-            struct.pop("$ref")
-            struct.update({**target, **struct})
+    _dereference(namespace, namespace)
 
     # At this point, any remaining refs are one-off objects in lists
     for struct in _find(namespace, lambda obj: any("$ref" in sub for sub in obj)):