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Description
Pandas version checks
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I have checked that this issue has not already been reported.
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I have confirmed this bug exists on the latest version of pandas.
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I have confirmed this bug exists on the main branch of pandas.
Reproducible Example
import pandas as pd _s = pd.Series([ {"k": f"{i}", "m": "q"} for i in range(5) ]) pd.json_normalize(_s,record_prefix="T")
Issue Description
The record_prefix is completely ignored and the resulting columns are note renamed.
k m
0 0 q
1 1 q
2 2 q
3 3 q
4 4 q
The issue is in L517-L527 where a short cut is taken for speed.
One option to fix this would be to pass the record_prefix as prefix to nested_to_record.
This is hidden in the documentation example by using a positional argument for the record path
>>> data = {"A": [1, 2]}
>>> pd.json_normalize(data, "A", record_prefix="Prefix.")
Prefix.0
0 1
1 2
Expected Behavior
The prefix should be applied (or an explicit warning be given)
T.k T.m
0 0 q
1 1 q
2 2 q
3 3 q
4 4 q
Installed Versions
INSTALLED VERSIONS
commit : c888af6
python : 3.13.3
python-bits : 64
OS : Linux
OS-release : 6.14.0-28-generic
Version : #28-Ubuntu SMP PREEMPT_DYNAMIC Wed Jul 23 12:05:14 UTC 2025
machine : x86_64
processor : x86_64
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8
pandas : 2.3.1
numpy : 2.3.2
pytz : 2025.2
dateutil : 2.9.0.post0
pip : 25.0
Cython : None
sphinx : None
IPython : 9.4.0
adbc-driver-postgresql: None
adbc-driver-sqlite : None
bs4 : 4.13.4
blosc : None
bottleneck : 1.5.0
dataframe-api-compat : None
fastparquet : 2024110
fsspec : 2025年5月1日
html5lib : 1.1
hypothesis : 6.135.20
gcsfs : 2025年5月1日
jinja2 : 3.1.6
lxml.etree : 5.4.0
matplotlib : 3.10.5
numba : None
numexpr : 2.11.0
odfpy : None
openpyxl : 3.1.5
pandas_gbq : 0.29.1
psycopg2 : None
pymysql : 1.4.6
pyarrow : 21.0.0
pyreadstat : 1.3.0
pytest : 8.4.1
python-calamine : None
pyxlsb : 1.0.10
s3fs : 2025年5月1日
scipy : 1.16.1
sqlalchemy : 2.0.43
tables : 3.10.2
tabulate : 0.9.0
xarray : 2025年6月1日
xlrd : 2.0.2
xlsxwriter : 3.2.5
zstandard : 0.23.0
tzdata : 2025.2
qtpy : 2.4.3
pyqt5 : None