Fix TypeError when pulling field that is None (#30145)

Author: bolkedebruin

doc/source/whatsnew/v1.0.0.rst

@@ -893,6 +893,7 @@ I/O
 - Bug in :func:`read_json` where default encoding was not set to ``utf-8`` (:issue:`29565`)
 - Bug in :class:`PythonParser` where str and bytes were being mixed when dealing with the decimal field (:issue:`29650`)
 - :meth:`read_gbq` now accepts ``progress_bar_type`` to display progress bar while the data downloads. (:issue:`29857`)
+- Bug in :func:`pandas.io.json.json_normalize` where a missing value in the location specified by `record_path` would raise a ``TypeError`` (:issue:`30148`)
 
 Plotting
 ^^^^^^^^

pandas/io/json/_normalize.py

@@ -3,13 +3,14 @@
 
 from collections import defaultdict
 import copy
-from typing import DefaultDict, Dict, List, Optional, Union
+from typing import Any, DefaultDict, Dict, Iterable, List, Optional, Union
 
 import numpy as np
 
 from pandas._libs.writers import convert_json_to_lines
 from pandas.util._decorators import deprecate
 
+import pandas as pd
 from pandas import DataFrame
 
 
@@ -229,14 +230,23 @@ def _json_normalize(
  Returns normalized data with columns prefixed with the given string.
  """
 
- def _pull_field(js, spec):
- result = js
+ def _pull_field(js: Dict[str, Any], spec: Union[List, str]) -> Iterable:
+ result = js # type: ignore
  if isinstance(spec, list):
  for field in spec:
  result = result[field]
  else:
  result = result[spec]
 
+ if not isinstance(result, Iterable):
+ if pd.isnull(result):
+ result = [] # type: ignore
+ else:
+ raise TypeError(
+ f"{js} has non iterable value {result} for path {spec}. "
+ "Must be iterable or null."
+ )
+
  return result
 
  if isinstance(data, list) and not data:

pandas/tests/io/json/test_normalize.py

@@ -462,6 +462,30 @@ def test_nested_flattening_consistent(self):
  # They should be the same.
  tm.assert_frame_equal(df1, df2)
 
+ def test_nonetype_record_path(self, nulls_fixture):
+ # see gh-30148
+ # should not raise TypeError
+ result = json_normalize(
+ [
+ {"state": "Texas", "info": nulls_fixture},
+ {"state": "Florida", "info": [{"i": 2}]},
+ ],
+ record_path=["info"],
+ )
+ expected = DataFrame({"i": 2}, index=[0])
+ tm.assert_equal(result, expected)
+
+ def test_non_interable_record_path_errors(self):
+ # see gh-30148
+ test_input = {"state": "Texas", "info": 1}
+ test_path = "info"
+ msg = (
+ f"{test_input} has non iterable value 1 for path {test_path}. "
+ "Must be iterable or null."
+ )
+ with pytest.raises(TypeError, match=msg):
+ json_normalize([test_input], record_path=[test_path])
+
 
 class TestNestedToRecord:
  def test_flat_stays_flat(self):