Support defaults from Pydantic fields

pdoc/doc.py

@@ -57,6 +57,15 @@
 from pdoc.doc_types import resolve_annotations
 from pdoc.doc_types import safe_eval_type
 
+_PYDANTIC_ENABLED: bool
+
+try:  # pragma: no cover
+    import pydantic
+except ImportError:  # pragma: no cover
+    _PYDANTIC_ENABLED = False
+finally:  # pragma: no cover
+    _PYDANTIC_ENABLED = True
+
 
 def _include_fullname_in_traceback(f):
     """
@@ -314,12 +323,27 @@ def members(self) -> dict[str, Doc]:
                     taken_from=taken_from,
                 )
             else:
+                default_value = obj
+
+                if (
+                    _PYDANTIC_ENABLED
+                    and isinstance(self.obj, type)
+                    and issubclass(self.obj, pydantic.BaseModel)
+                ):
+                    pydantic_fields = self.obj.__pydantic_fields__
+
+                    default_value = (
+                        pydantic_fields[name].default
+                        if name in pydantic_fields
+                        else obj
+                    )
+
                 doc = Variable(
                     self.modulename,
                     qualname,
                     docstring="",
                     annotation=self._var_annotations.get(name, empty),
-                    default_value=obj,
+                    default_value=default_value,
                     taken_from=taken_from,
                 )
             if self._var_docstrings.get(name):

pyproject.toml

@@ -51,6 +51,7 @@ dev-dependencies = [
     "pytest-timeout>=2.3.1",
     "hypothesis>=6.113.0",
     "pdoc-pyo3-sample-library>=1.0.11",
+    "pydantic>=2.11.4",
 ]
 
 [build-system]

test/test_snapshot.py

@@ -166,6 +166,7 @@ def outfile(self, format: str) -> Path:
             "include_undocumented": False,
         },
     ),
+    Snapshot("with_pydantic"),
 ]
 
 

test/testdata/with_pydantic.py

@@ -0,0 +1,12 @@
+"""
+A small example with Pydantic entities.
+"""
+
+import pydantic
+
+
+class Foo(pydantic.BaseModel):
+    a: int = pydantic.Field(default=1, description="Docstring for a")
+
+    b: int = 2
+    """Docstring for b."""

test/testdata/with_pydantic.txt

@@ -0,0 +1 @@
+<module with_pydantic  # A small example with…>