enable callable group_by

Author: echan5

deepdiff/diff.py

@@ -157,7 +157,7 @@ def __init__(self,
                  exclude_regex_paths: Union[str, List[str], Pattern[str], List[Pattern[str]], None]=None,
                  exclude_types: Optional[List[type]]=None,
                  get_deep_distance: bool=False,
-                 group_by: Union[str, Tuple[str, str], None]=None,
+                 group_by: Union[str, Tuple[str, str], Callable, None]=None,
                  group_by_sort_key: Union[str, Callable, None]=None,
                  hasher: Optional[Callable]=None,
                  hashes: Optional[Dict[Any, Any]]=None,
@@ -1834,7 +1834,32 @@ def _get_view_results(self, view):
 
     @staticmethod
     def _get_key_for_group_by(row, group_by, item_name):
+        """
+        Get the key value to group a row by, using the specified group_by parameter.
+
+        Example
+            >>> row = {'first': 'John', 'middle': 'Joe', 'last': 'Smith'}
+            >>> group_by_key = DeepDiff._get_key_for_group_by(row, 'first', 't1')
+            'John'
+            >>> nested_row = {'id': 123, 'demographics': {'names': {'first': 'John', 'middle': 'Joe', 'last': 'Smith'}}}
+            >>> group_by_key = DeepDiff._get_key_for_group_by(nested_row,
+                                                              lambda x: x['demographics']['names']['first'], 't1')
+            'John'
+
+        Args:
+            row (dict): The dictionary (row) to extract the group by key from.
+            group_by (str or callable): The key name or function to call to get to the key value to group by.
+            item_name (str): The name of the item, used for error messages.
+
+        Returns:
+            str: The key value to group by.
+
+        Raises:
+            KeyError: If the specified key is not found in the row.
+        """
         try:
+            if callable(group_by):
+                return group_by(row)
             return row.pop(group_by)
         except KeyError:
             logger.error("Unable to group {} by {}. The key is missing in {}".format(item_name, group_by, row))