bug: Crash when using non-literal values as Pydantic field attributes

[nardi]

Description of the bug

If using a non-literal value as the description argument to a Pydantic Field, griffe will crash when trying to parse it using ast.literal_eval.

To Reproduce

import griffe

static_model = """
import pydantic

class TestModel(pydantic.BaseModel):
    abc: str = pydantic.Field(description="xyz")
"""

with griffe.temporary_visited_package(
    "package",
    modules={"__init__.py": static_model},
    extensions=griffe.load_extensions("griffe_pydantic"),
) as package:
    assert package["TestModel"]["abc"].docstring.value == "xyz"

dynamic_model = """
import pydantic

desc = "xyz"

class TestModel(pydantic.BaseModel):
    abc: str = pydantic.Field(description=desc)
"""

with griffe.temporary_visited_package(
    "package",
    modules={"__init__.py": dynamic_model},
    extensions=griffe.load_extensions("griffe_pydantic"),
) as package:
    assert package["TestModel"]["abc"].docstring.value == "xyz"

Full traceback

Full traceback

---------------------------------------------------------------------------
ValueError                                Traceback (most recent call last)
Cell In[23], line 26
     15     assert package["TestModel"]["abc"].docstring.value == "xyz"
     17 dynamic_model = """
     18 import pydantic
     19 
   (...)
     23     abc: str = pydantic.Field(description=desc)
     24 """
---> 26 with griffe.temporary_visited_package(
     27     "package",
     28     modules={"__init__.py": dynamic_model},
     29     extensions=griffe.load_extensions("griffe_pydantic"),
     30 ) as package:
     31     assert package["TestModel"]["abc"].docstring.value == "xyz"

File [...]\Lib\contextlib.py:137, in _GeneratorContextManager.__enter__(self)
    135 del self.args, self.kwds, self.func
    136 try:
--> 137     return next(self.gen)
    138 except StopIteration:
    139     raise RuntimeError("generator didn't yield") from None

File [...]\Lib\site-packages\_griffe\tests.py:167, in temporary_visited_package(package, modules, init, inits, extensions, docstring_parser, docstring_options, lines_collection, modules_collection, allow_inspection, store_source, resolve_aliases, resolve_external, resolve_implicit)
    137 """Create and visit a temporary package.
    138 
    139 Parameters:
   (...)
    164     A module.
    165 """
    166 with temporary_pypackage(package, modules, init=init, inits=inits) as tmp_package:
--> 167     yield load(  # type: ignore[misc]
    168         tmp_package.name,
    169         search_paths=[tmp_package.tmpdir],
    170         extensions=extensions,
    171         docstring_parser=docstring_parser,
    172         docstring_options=docstring_options,
    173         lines_collection=lines_collection,
    174         modules_collection=modules_collection,
    175         allow_inspection=allow_inspection,
    176         store_source=store_source,
    177         resolve_aliases=resolve_aliases,
    178         resolve_external=resolve_external,
    179         resolve_implicit=resolve_implicit,
    180         force_inspection=False,
    181     )

File [...]\Lib\site-packages\_griffe\loader.py:811, in load(objspec, submodules, try_relative_path, extensions, search_paths, docstring_parser, docstring_options, lines_collection, modules_collection, allow_inspection, force_inspection, store_source, find_stubs_package, resolve_aliases, resolve_external, resolve_implicit)
    737 """Load and return a Griffe object.
    738 
    739 In Griffe's context, loading means:
   (...)
    798     A Griffe object.
    799 """
    800 loader = GriffeLoader(
    801     extensions=extensions,
    802     search_paths=search_paths,
   (...)
    809     store_source=store_source,
    810 )
--> 811 result = loader.load(
    812     objspec,
    813     submodules=submodules,
    814     try_relative_path=try_relative_path,
    815     find_stubs_package=find_stubs_package,
    816 )
    817 if resolve_aliases:
    818     loader.resolve_aliases(implicit=resolve_implicit, external=resolve_external)

File [...]\Lib\site-packages\_griffe\loader.py:186, in GriffeLoader.load(self, objspec, submodules, try_relative_path, find_stubs_package)
    183     logger.exception("Could not load package %s", package)
    184     raise
--> 186 return self._post_load(top_module, obj_path)

File [...]\Lib\site-packages\_griffe\loader.py:212, in GriffeLoader._post_load(self, module, obj_path)
    210 # Package is loaded, we now retrieve the initially requested object and return it.
    211 obj = self.modules_collection.get_member(obj_path)
--> 212 self.extensions.call("on_package_loaded", pkg=module, loader=self)
    213 return obj

File [...]\Lib\site-packages\_griffe\extensions\base.py:313, in Extensions.call(self, event, **kwargs)
    306 """Call the extension hook for the given event.
    307 
    308 Parameters:
    309     event: The triggered event.
    310     **kwargs: Arguments passed to the hook.
    311 """
    312 for extension in self._extensions:
--> 313     getattr(extension, event)(**kwargs)

File [...]\Lib\site-packages\griffe_pydantic\extension.py:42, in PydanticExtension.on_package_loaded(self, pkg, **kwargs)
     40 def on_package_loaded(self, *, pkg: Module, **kwargs: Any) -> None:  # noqa: ARG002
     41     """Detect models once the whole package is loaded."""
---> 42     static.process_module(pkg, processed=self.processed, schema=self.schema)

File [...]\Lib\site-packages\griffe_pydantic\static.py:167, in process_module(mod, processed, schema)
    164 for cls in mod.classes.values():
    165     # Don't process aliases, real classes will be processed at some point anyway.
    166     if not cls.is_alias:
--> 167         process_class(cls, processed=processed, schema=schema)
    169 for submodule in mod.modules.values():
    170     process_module(submodule, processed=processed, schema=schema)

File [...]\Lib\site-packages\griffe_pydantic\static.py:146, in process_class(cls, processed, schema)
    144 for member in cls.all_members.values():
    145     if isinstance(member, Attribute):
--> 146         process_attribute(member, cls, processed=processed)
    147     elif isinstance(member, Function):
    148         process_function(member, cls, processed=processed)

File [...]\Lib\site-packages\griffe_pydantic\static.py:100, in process_attribute(attr, cls, processed)
     98 # Populate docstring from the field's `description` argument.
     99 if not attr.docstring and (docstring := kwargs.get("description", None)):
--> 100     attr.docstring = Docstring(ast.literal_eval(docstring), parent=attr)

File [...]\Lib\ast.py:110, in literal_eval(node_or_string)
    108                 return left - right
    109     return _convert_signed_num(node)
--> 110 return _convert(node_or_string)

File [...]\Lib\ast.py:109, in literal_eval.<locals>._convert(node)
    107         else:
    108             return left - right
--> 109 return _convert_signed_num(node)

File [...]\Lib\ast.py:83, in literal_eval.<locals>._convert_signed_num(node)
     81     else:
     82         return - operand
---> 83 return _convert_num(node)

File [...]\Lib\ast.py:74, in literal_eval.<locals>._convert_num(node)
     72 def _convert_num(node):
     73     if not isinstance(node, Constant) or type(node.value) not in (int, float, complex):
---> 74         _raise_malformed_node(node)
     75     return node.value

File [...]\Lib\ast.py:71, in literal_eval.<locals>._raise_malformed_node(node)
     69 if lno := getattr(node, 'lineno', None):
     70     msg += f' on line {lno}'
---> 71 raise ValueError(msg + f': {node!r}')

ValueError: malformed node or string: ExprName(name='desc', parent=Class('TestModel', 6, 7))

Expected behavior

Either an error message that explains the dynamic description is not supported before halting, a warning and an empty docstring, or some kind of dynamic resolution of the description attribute.

Environment information

• System: Windows-10-10.0.26100-SP0
• Python: cpython 3.11.6 ([...]\python.exe)
• Environment variables:
• Installed packages:
  • griffe-pydantic v1.1.0

Additional context

Sibling to feature request here.

[pawamoy]

Thanks @nardi!

We won't support dynamic values statically (at least for now), but the extension should definitely not crash anyway 👍