[python-package] bug : dump_model json loads failed

[Fhwang0926]

Description

error when "json.loads()" with "\" special charset using key

for exam

{ "\" : "aa" }

so should be exist escape code

Reproducible example

it happend used "shap.TreeExplainer", it is anothor open source, but referce it so write issue

Environment info

LightGBM version or commit hash:

using lightgbm-4.3.0.dist-info

Command(s) you used to install LightGBM

Traceback (most recent call last):
  File "/home/f1/wmds-deep-scanner/agent.py", line 411, in predict
    explain = getXaiDetector(model_name, value)
  File "/home/f1/wmds-deep-scanner/agent.py", line 214, in getXaiDetector
    explainer = shap.TreeExplainer(MODEL_MAP[model_name])
  File "/home/f1/wmds-deep-scanner/virtual/lib/python3.10/site-packages/shap/explainers/_tree.py", line 195, in __init__
    self.model = TreeEnsemble(model, self.data, self.data_missing, model_output)
  File "/home/f1/wmds-deep-scanner/virtual/lib/python3.10/site-packages/shap/explainers/_tree.py", line 1140, in __init__
    tree_info = self.original_model.dump_model()["tree_info"]
  File "/home/f1/wmds-deep-scanner/virtual/lib/python3.10/site-packages/lightgbm/basic.py", line 4387, in dump_model
    ret = json.loads(string_buffer.value.decode('utf-8'), object_hook=object_hook)
  File "/usr/lib/python3.10/json/__init__.py", line 346, in loads
    return _default_decoder.decode(s)
  File "/usr/lib/python3.10/json/decoder.py", line 337, in decode
    obj, end = self.raw_decode(s, idx=_w(s, 0).end())
  File "/usr/lib/python3.10/json/decoder.py", line 353, in raw_decode
    obj, end = self.scan_once(s, idx)
json.decoder.JSONDecodeError: Expecting ',' delimiter: line 9 column 468 (char 631)

Additional Comments

it is happend under here, into basic.py

origin code

# basic.py, line 4661

ret = json.loads(string_buffer.value.decode("utf-8"), object_hook=object_hook)
ret["pandas_categorical"] = json.loads(
    json.dumps(
        self.pandas_categorical,
        default=_json_default_with_numpy,
    )
)

fix code

# basic.py, line 4661

ret = json.loads(string_buffer.value.decode("utf-8").replace("\\", "\\\\"), object_hook=object_hook)
ret["pandas_categorical"] = json.loads(
    json.dumps(
        self.pandas_categorical,
        default=_json_default_with_numpy,
    )
)

how about it ?, Can i do pull request ?

[jameslamb]

Thanks for using LightGBM.

I don't fully understand this report. Can you provide a minimal, reproducible example showing this behavior? For example, modify this code in a way that causes LightGBM to generate this error:

import lightgbm as lgb
from sklearn.datasets import make_regression

X, y = make_regression()
model = lgb.LGBMRegressor().fit(X , y)