feat: Support Pydantic's PrivateAttr

Issue-43: #43
PR-49: #49

Author: danielgafni

src/griffe_pydantic/_internal/static.py

@@ -82,6 +82,13 @@ def _process_attribute(attr: Attribute, cls: Class, *, processed: set[str]) -> N
     if "class-attribute" in attr.labels and "instance-attribute" not in attr.labels:
         return
 
+    # PrivateAttr values are not public fields.
+    if isinstance(attr.value, ExprCall) and attr.value.function.canonical_path in {
+        "pydantic.PrivateAttr",
+        "pydantic.fields.PrivateAttr",
+    }:
+        return
+
     # Check if the annotation is Annotated[type, Field(...)]
     field_call = None
     if (
@@ -96,9 +103,16 @@ def _process_attribute(attr: Attribute, cls: Class, *, processed: set[str]) -> N
             attr.annotation = slice_elements[0]
 
         for element in slice_elements:
-            if isinstance(element, ExprCall) and element.function.canonical_path == "pydantic.Field":
-                field_call = element
-                break
+            if isinstance(element, ExprCall):
+                # PrivateAttr values are not public fields.
+                if element.function.canonical_path in {
+                    "pydantic.PrivateAttr",
+                    "pydantic.fields.PrivateAttr",
+                }:
+                    return
+                if element.function.canonical_path == "pydantic.Field":
+                    field_call = element
+                    break
 
     kwargs = {}
     if field_call is not None:

tests/test_extension.py

@@ -259,3 +259,40 @@ class Model(BaseModel):
         # Check that annotation is the actual type, not Annotated[...]
         assert str(package["Model.a"].annotation) == "int"
         assert str(package["Model.b"].annotation) == "int"
+
+
+def test_ignore_private_attrs() -> None:
+    """Test the extension ignores private attributes."""
+    code = """
+    from pydantic import BaseModel, PrivateAttr
+
+    class Model(BaseModel):
+        field: str
+        _private: str = PrivateAttr(default="secret")
+    """
+    with temporary_visited_package(
+        "package",
+        modules={"__init__.py": code},
+        extensions=Extensions(PydanticExtension(schema=False)),
+    ) as package:
+        assert "pydantic-field" in package["Model.field"].labels
+        assert "pydantic-field" not in package["Model._private"].labels
+
+
+def test_ignore_private_attrs_annotated() -> None:
+    """Test the extension ignores private attributes with Annotated syntax."""
+    code = """
+    from pydantic import BaseModel, PrivateAttr
+    from typing import Annotated
+
+    class Model(BaseModel):
+        field: str
+        _private: Annotated[str, PrivateAttr(default="secret")]
+    """
+    with temporary_visited_package(
+        "package",
+        modules={"__init__.py": code},
+        extensions=Extensions(PydanticExtension(schema=False)),
+    ) as package:
+        assert "pydantic-field" in package["Model.field"].labels
+        assert "pydantic-field" not in package["Model._private"].labels