Series.to_json - invalid handling of quotes

[Enteee]

Code Sample, a copy-pastable example if possible

import pandas as pd

pd.DataFrame([
  {'A':'a', 'B':'b'}
]).groupby(
  ['A','B']
).apply(
  lambda x: x.to_dict(orient='records')
).to_json()

produces an invalid JSON string:

'{"["a","b"]":[{"A":"a","B":"b"}]}'

Problem description

For the given transformation, the output of to_json of a pandas.core.series.Series is not a valid JSON object.

Would be nice if it was.

Expected Output

'{"[\'a\',\'b\']":[{"A":"a","B":"b"}]}'

Output of pd.show_versions()

INSTALLED VERSIONS

commit : None
python : 3.7.5.final.0
python-bits : 64
OS : Linux
OS-release : 4.19.84
machine : x86_64
processor :
byteorder : little
LC_ALL : None
LANG : en_US.UTF-8
LOCALE : en_US.UTF-8

pandas : 0.25.2
numpy : 1.17.3
pytz : 2019.3
dateutil : 2.8.0
pip : None
setuptools : None
Cython : None
pytest : None
hypothesis : None
sphinx : None
blosc : None
feather : None
xlsxwriter : None
lxml.etree : 4.4.1
html5lib : 1.0.1
pymysql : None
psycopg2 : None
jinja2 : None
IPython : 7.8.0
pandas_datareader: None
bs4 : 4.8.1
bottleneck : 1.2.1
fastparquet : None
gcsfs : None
lxml.etree : 4.4.1
matplotlib : None
numexpr : 2.7.0
odfpy : None
openpyxl : 3.0.0
pandas_gbq : None
pyarrow : None
pytables : None
s3fs : None
scipy : 1.3.1
sqlalchemy : 1.3.10
tables : None
xarray : None
xlrd : 1.2.0
xlwt : 1.3.0
xlsxwriter : None

[ohad83]

Seems to work fine in master, output:
'{"(\'a\', \'b\')":[{"A":"a","B":"b"}]}'

[Enteee]

Interesting, I can for sure reproduce this issue with 0.25.2.
So how do we go forward with this issue? Do you want me to close this?

[ohad83]

It does reproduce in 0.25.2 and also 0.25.3.
I believe this is a duplicate of #20500 and closed by #27618, so yeah, it can be closed.

[Enteee]

k, thx.