pd.NA is converted to {} instead of null with pd.DataFrame.to_json

[pvieito]

Code Sample

import numpy as np
import pandas as pd

pd.DataFrame([[np.nan]], columns=["NA"]).to_json(orient="records")
# '[{"NA":null}]'
pd.DataFrame([[None]], columns=["NA"]).to_json(orient="records")
# '[{"NA":null}]'
pd.DataFrame([[pd.NA]], columns=["NA"]).to_json(orient="records")
# '[{"NA":{}}]'

Problem Description

pd.NA should behave as np.nan and None when converting a DataFrame to JSON.

Expected Output

In the resulting JSON the pd.NA instances should be converted to JSON's null.

[jorisvandenbossche]

@pvieito Thanks for the report! That's indeed buggy

[itsshavar]

json writer is having some issue

[ArtificialQualia]

I got this one, some changes are needed in ujson.