pydoc error when executed on a file containing SQLAlchemy models

Question

I'm trying to run pydoc on a Python file using my Windows machine. The file contains SQLAlchemy models, but have been struggling with an error.

I appreciate it if I can receive some guidance. Attached below: the command that I execute, the target Python file and the error that I'm getting.

My command is as follows: python -m pydoc -w objects

Here is my Python file, objects.py.

from flask import Flask
from flask_sqlalchemy import SQLAlchemy
import os
app = Flask(__name__)
app.app_context().push()
app.config['SQLALCHEMY_DATABASE_URI'] = 'postgresql://postgres:mycoolpassword@localhost:5432/mydb'
db = SQLAlchemy(app)
class Book(db.Model):
 """
 Docstring for my class
 Col1
 Col2
 """
 __tablename__ = 'mytable'
 
 col1 = db.Column(db.Integer, primary_key = True)
 col2 = db.Column(db.Integer)
db.drop_all()
db.create_all()

Here is the error that I'm receiving.

$ python -m pydoc -w objects
Traceback (most recent call last):
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\runpy.py", line 194, in _run_module_as_main
 return _run_code(code, main_globals, None,
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\runpy.py", line 87, in _run_code
 exec(code, run_globals)
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\pydoc.py", line 2744, in <module>
 cli()
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\pydoc.py", line 2704, in cli
 writedoc(arg)
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\pydoc.py", line 1697, in writedoc
 page = html.page(describe(object), html.document(object, name))
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\pydoc.py", line 380, in document
 if inspect.ismodule(object): return self.docmodule(*args)
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\pydoc.py", line 738, in docmodule
 contents.append(self.document(value, key, name, fdict, cdict))
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\pydoc.py", line 381, in document
 if inspect.isclass(object): return self.docclass(*args)
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\pydoc.py", line 843, in docclass
 for name, kind, cls, value in classify_class_attrs(object)
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\pydoc.py", line 204, in classify_class_attrs
 for (name, kind, cls, value) in inspect.classify_class_attrs(object):
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\inspect.py", line 443, in classify_class_attrs
 srch_obj = getattr(srch_cls, name, None)
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\site-packages\flask_sqlalchemy\model.py", line 30, in __get__
 return cls.query_class(
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\orm\query.py", line 273, in __init__
 self._set_entities(entities)
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\orm\query.py", line 282, in _set_entities
 self._raw_columns = [
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\orm\query.py", line 283, in <listcomp>
 coercions.expect(
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\sql\coercions.py", line 413, in expect
 resolved = impl._literal_coercion(
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\sql\coercions.py", line 651, in _literal_coercion
 self._raise_for_expected(element, argname)
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\sql\coercions.py", line 1139, in _raise_for_expected
 return super()._raise_for_expected(
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\sql\coercions.py", line 710, in _raise_for_expected
 super()._raise_for_expected(
 File "C:\Users\Boco\AppData\Local\Programs\Python\Python38\lib\site-packages\sqlalchemy\sql\coercions.py", line 535, in _raise_for_expected
 raise exc.ArgumentError(msg, code=code) from err
sqlalchemy.exc.ArgumentError: Column expression, FROM clause, or other columns clause element expected, got <class 'sqlalchemy.orm.decl_api.Model'>.

I tried to reinstall flask and SQLAlchemy and ensure that all dependencies such as psycopg2-binary are all installed.

• snakecharmerb: pydoc imports files to inspect them, so any top-level code in the file will be executed. The traceback is consistent with an invalid SQLAlchemy query being exwcuted. Is the example file really what is being documented?
• ZIF: Yes, it's in fact the example. It successfully runs but the issue is when I ran pydoc. Before I posted, I only changed some parameters to the URL such as password and DB name.
• snakecharmerb: If I run pydoc on a file containing the above code it prints 'No Python documentation found for <filename>'', some boilerplate about help() then 'shell returned 1'. Does your module impor tother modules by any chance, which could have queries in their top-level code?
• ZIF: Thank you @snakecharmerb. To my knowledge, my module does not import other modules other than the ones listed at the top of the file. I'm afraid this is a bug in pydoc. Not sure how to report it though.

Answer 1

It seems that pydoc has a bug when it comes to Python files with DB models. I ended up using pdoc and it generated the documentation with no issues.

pip install pdoc
pdoc objects.py