Support Pydantic v1 field metadata

pdoc/_pydantic.py

@@ -41,15 +41,22 @@ def default_value(parent: ClassOrModule, name: str, obj: Any) -> Any:
     For all other objects, return `obj` as-is.
     """
     if is_pydantic_model(parent):
-        pydantic_fields = parent.__pydantic_fields__
+        pydantic_fields = getattr(parent, "__pydantic_fields__", None)
+        if pydantic_fields is None:
+            pydantic_fields = parent.__fields__
         return pydantic_fields[name].default if name in pydantic_fields else obj
 
     return obj
 
 
 def get_field_docstring(parent: ClassOrModule, field_name: str) -> str | None:
     if is_pydantic_model(parent):
-        if field := parent.__pydantic_fields__.get(field_name, None):
+        pydantic_fields = getattr(parent, "__pydantic_fields__", None)
+        if pydantic_fields is None:
+            if field := parent.__fields__.get(field_name):
+                return getattr(field, "field_info", field).description
+            return None
+        if field := pydantic_fields.get(field_name):
             return field.description
         if computed := parent.__pydantic_computed_fields__.get(field_name, None):
             return computed.description

test/test__pydantic.py

@@ -1,8 +1,10 @@
 from functools import cached_property
 
 import pydantic
+import pydantic.v1 as pydantic_v1
 
 from pdoc import _pydantic
+from pdoc import extract
 import pdoc.doc
 
 
@@ -39,3 +41,28 @@ def test_with_pydantic(monkeypatch):
     assert not _pydantic.is_pydantic_model(pdoc.doc.Module)
     assert _pydantic.get_field_docstring(pdoc.doc.Module, "kind") is None
     assert _pydantic.default_value(pdoc.doc.Module, "kind", "module") == "module"
+
+
+def test_with_pydantic_v1(monkeypatch, tmp_path):
+    monkeypatch.setattr(_pydantic, "pydantic", pydantic_v1)
+
+    class LegacyModel(pydantic_v1.BaseModel):
+        name: str = pydantic_v1.Field(
+            default="Jane Doe", description="legacy description"
+        )
+
+    assert _pydantic.is_pydantic_model(LegacyModel)
+    assert _pydantic.get_field_docstring(LegacyModel, "name") == "legacy description"
+    assert _pydantic.get_field_docstring(LegacyModel, "unknown") is None
+    assert _pydantic.default_value(LegacyModel, "name", None) == "Jane Doe"
+    assert _pydantic.default_value(LegacyModel, "unknown", "fallback") == "fallback"
+
+    module_file = tmp_path / "legacy_model.py"
+    module_file.write_text(
+        "from pydantic.v1 import BaseModel, Field\n"
+        "class LegacyModel(BaseModel):\n"
+        "    name: str = Field(default='Jane Doe', description='legacy description')\n"
+    )
+    module = extract.load_module(extract.parse_spec(module_file))
+    assert "LegacyModel" in pdoc.doc.Module(module).members
+    assert "legacy description" in pdoc.pdoc(str(module_file))