schema descriptor should raise AttributeError if build_schema_ is not implemented

[amerberg]

As of #2136, pandera uses a schema descriptor which can cause some problems when inspecting models that extend DataFrameModel classes:

import pydoc

import pandas as pd
import pandera.pandas as pa
from pandera.typing import Series
from pandera.api.dataframe.model import DataFrameModel as BaseDataFrameModel
from pandera.pandas import DataFrameModel as PandasDataFrameModel
from pandera.polars import DataFrameModel as PolarsDataFrameModel


class BaseModel(BaseDataFrameModel):
    name: Series[pa.String] = pa.Field()


class PandasModel(PandasDataFrameModel, BaseModel):
    pass


class PolarsModel(PolarsDataFrameModel, BaseModel):
    pass


print(pydoc.render_doc(PandasModel))

The pydoc.render_doc(PandasModel) raises NotImplementedError, because pydoc walks the MRO and attempts to access the __schema__ attribute on pandera.api.dataframe.model.DataFrameModel.

The fix here is to modify the _SchemaDescriptor to catch the NotImplementedError and raise an AttributeError, which is handled better by pydoc.

[codecov]

Codecov Report

❌ Patch coverage is 75.00000% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 83.86%. Comparing base (71255eb) to head (ed8ec8b).
⚠️ Report is 7 commits behind head on main.

Files with missing lines	Patch %	Lines
pandera/api/dataframe/model.py	75.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2197      +/-   ##
==========================================
- Coverage   83.86%   83.86%   -0.01%     
==========================================
  Files         137      137              
  Lines       10607    10610       +3     
==========================================
+ Hits         8896     8898       +2     
- Misses       1711     1712       +1     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.

[amerberg]

The test failure seems to be essentially a fluke. The tests ran successefully, but there was an error uploading coverage:

Run codecov/codecov-action@v4
eventName: pull_request
baseRef: unionai-oss:main | headRef: amerberg:schema_not_implemented
==> Fork detected, tokenless uploading used
==> macos OS detected
Error: getaddrinfo ENOTFOUND cli.codecov.io
    at GetAddrInfoReqWrap.onlookupall [as oncomplete] (node:dns:122:26)