BUG: fix for pd.json_normalize on non string keys

pandas/io/json/_normalize.py

@@ -552,7 +552,7 @@ def _pull_records(js: dict[str, Any], spec: list | str) -> list:
     lengths = []
 
     meta_vals: DefaultDict = defaultdict(list)
-    meta_keys = [sep.join(val) for val in _meta]
+    meta_keys = [sep.join(map(str, val)) for val in _meta]
 
     def _recursive_extract(data, path, seen_meta, level: int = 0) -> None:
         if isinstance(data, dict):

pandas/tests/io/json/test_normalize.py

@@ -927,3 +927,14 @@ def test_series_non_zero_index(self):
             index=[1, 2, 3],
         )
         tm.assert_frame_equal(result, expected)
+
+    def test_json_normalize_non_str_keys(self):
+        # Test that json_normalize handles non-string meta
+        # keys correctly when record_path is used
+
+        data_list = [{"a": 1, 12: "meta_value", "nested": [{"b": 2}]}]
+
+        result = json_normalize(data_list, record_path=["nested"], meta=[12])
+        expected = DataFrame({"b": [2], "12": ["meta_value"]})
+
+        tm.assert_frame_equal(result, expected)