fix: Creation of fully un-annotated subobjects.

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "dataclass-settings"
-version = "0.2.0"
+version = "0.2.1"
 description = "Declarative dataclass settings."
 
 repository = "https://github.com/dancardin/dataclass-settings"

src/dataclass_settings/base.py

@@ -99,8 +99,11 @@ def collect(
                     break
 
         if value is not None:
-            result[field.name] = field.map_value(value)
+            try:
+                mapped_value = field.map_value(value)
+            except Exception:
+                pass
+            else:
+                result[field.name] = mapped_value
 
-    if not result:
-        return None
     return result

src/dataclass_settings/class_inspect.py

@@ -58,7 +58,7 @@ class Field:
     name: str
     type: type
     annotations: tuple[Any, ...]
-    mapper: Callable[..., Any] | None = None
+    mapper: Callable[..., Any]
 
     @classmethod
     def from_dataclass(cls, typ: Type) -> list[Self]:
@@ -81,6 +81,7 @@ def from_pydantic(cls, typ: Type) -> list[Self]:
                 name=name,
                 type=f.annotation,
                 annotations=tuple(f.metadata),
+                mapper=get_type(f.annotation),
             )
             fields.append(field)
         return fields
@@ -93,6 +94,7 @@ def from_pydantic_dataclass(cls, typ: Type) -> list[Self]:
                 name=name,
                 type=f.annotation,
                 annotations=tuple(f.metadata),
+                mapper=get_type(f.annotation),
             )
             fields.append(field)
         return fields
@@ -137,11 +139,9 @@ def get_nested_type(self) -> Type | None:
         return supported_arg
 
     def map_value(self, value: str | dict[str, Any]):
-        if self.mapper:
-            if isinstance(value, str):
-                return self.mapper(value)
-            return self.mapper(**value)
-        return value
+        if isinstance(value, str):
+            return self.mapper(value)
+        return self.mapper(**value)
 
 
 def fields(cls: type):
@@ -159,3 +159,9 @@ def fields(cls: type):
         return Field.from_attrs(cls)
 
     raise NotImplementedError()  # pragma: no cover
+
+
+def get_type(typ):
+    if typing_inspect.is_optional_type(typ):
+        return get_args(typ)[0]
+    return typ

tests/test_class_inspect.py

@@ -0,0 +1,13 @@
+from dataclass_settings import load_settings
+from pydantic import BaseModel
+
+
+def test_successful_validation_of_fully_default_subobjects():
+    class Foo(BaseModel):
+        foo: int = 0
+
+    class Config(BaseModel):
+        foo: Foo
+
+    config = load_settings(Config)
+    assert config == Config(foo=Foo(foo=0))