Speed up BIDSLayout.get(return_type='id', ...)

bids/layout/layout.py

@@ -533,7 +533,7 @@ def to_df(self, metadata=False, **filters):
             data.loc[o] = pd.Series(dtype=float)
 
         return data.reset_index()
-
+    
     def get(self, return_type='object', target=None, scope='all',
             regex_search=False, absolute_paths=None, invalid_filters='error',
             **filters):
@@ -673,10 +673,8 @@ def get(self, return_type='object', target=None, scope='all',
                 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 = (x.get_entities(metadata=metadata) for x in results)
+                ent_iter = (x.entities for x in results)
                 results = list({
                     ents[target] for ents in ent_iter if target in ents
                 })

bids/layout/models.py

@@ -312,6 +312,9 @@ def get_entities(self, metadata=False, values='tags'):
             A dict, where keys are entity names and values are Entity
             instances.
         """
+        if metadata is None and values == 'tags':
+            return self.entities
+
         session = object_session(self)
         query = (session.query(Tag)
                  .filter_by(file_path=self.path)