Nested containers

src/magicgui/schema/_guiclass.py

@@ -27,6 +27,8 @@
 
     from typing_extensions import TypeGuard
 
+    from magicgui.types import NestedValueWidgets
+
     # fmt: off
     class GuiClassProtocol(Protocol):
         """Protocol for a guiclass."""
@@ -243,7 +245,7 @@ def widget(self) -> ContainerWidget:
 
     def __get__(
         self, instance: object | None, owner: type
-    ) -> ContainerWidget[BaseValueWidget] | GuiBuilder:
+    ) -> ContainerWidget[NestedValueWidgets] | GuiBuilder:
         if instance is None:
             return self
         wdg = build_widget(instance)

src/magicgui/schema/_ui_field.py

@@ -20,7 +20,7 @@
 
 from typing_extensions import TypeGuard, get_args, get_origin
 
-from magicgui.types import JsonStringFormats, Undefined, _Undefined
+from magicgui.types import JsonStringFormats, NestedValueWidgets, Undefined, _Undefined
 
 if TYPE_CHECKING:
     from collections.abc import Iterable, Iterator, Mapping
@@ -394,7 +394,9 @@
             kwargs.pop("name", None)
         return dc.replace(self, **kwargs)
 
-    def create_widget(self, value: T | _Undefined = Undefined) -> BaseValueWidget[T]:
+    def create_widget(
+        self, value: T | _Undefined = Undefined
+    ) -> BaseValueWidget[T] | NestedValueWidgets:
         """Create a new Widget for this field."""
         from magicgui.type_map import get_widget_class
 
@@ -441,7 +443,20 @@
             opts["min"] = d["exclusive_minimum"] + m
 
         value = value if value is not Undefined else self.get_default()  # type: ignore
-        cls, kwargs = get_widget_class(value=value, annotation=self.type, options=opts)
+        try:
+            cls, kwargs = get_widget_class(
+                value=value, annotation=self.type, options=opts
+            )
+        except ValueError:
+            try:
+                wdg = build_widget(self.type)
+                wdg.label = self.name if self.name else ""
+                return wdg
+            except TypeError as e:
+                raise TypeError(
+                    f"Could not create widget for field {self.name!r} ",
+                    f"with value {value!r}",
+                ) from e
         return cls(**kwargs)  # type: ignore
 
 
@@ -786,7 +801,7 @@
     values: Mapping[str, Any] | None = None,
     *,
     container_kwargs: Mapping | None = None,
-) -> ContainerWidget[BaseValueWidget]:
+) -> ContainerWidget[NestedValueWidgets]:
     """Create a container widget from a sequence of UiFields.
 
     This function is the heart of build_widget.
@@ -849,7 +864,7 @@
 
 
 # TODO: unify this with magicgui
-def build_widget(cls_or_instance: Any) -> ContainerWidget[BaseValueWidget]:
+def build_widget(cls_or_instance: Any) -> ContainerWidget[NestedValueWidgets]:
     """Build a magicgui widget from a dataclass, attrs, pydantic, or function."""
     values = None if isinstance(cls_or_instance, type) else _get_values(cls_or_instance)
     fields = get_ui_fields(cls_or_instance)

src/magicgui/types.py

@@ -11,7 +11,12 @@
 
 if TYPE_CHECKING:
     from magicgui.widgets import FunctionGui
-    from magicgui.widgets.bases import CategoricalWidget, Widget
+    from magicgui.widgets.bases import (
+        BaseValueWidget,
+        CategoricalWidget,
+        ContainerWidget,
+        Widget,
+    )
     from magicgui.widgets.protocols import WidgetProtocol
 
 
@@ -29,6 +34,9 @@ class ChoicesDict(TypedDict):
 WidgetRef = Union[str, WidgetClass]
 #: A :attr:`WidgetClass` (or a string representation of one) and a dict of kwargs
 WidgetTuple = tuple[WidgetRef, dict[str, Any]]
+#: A [`ValueWidget`][magicgui.widgets.ValueWidget] class or a
+#: [`ContainerWidget`][magicgui.widgets.ContainerWidget] class for nesting those
+NestedValueWidgets = Union["BaseValueWidget", "ContainerWidget[NestedValueWidgets]"]
 #: An iterable that can be used as a valid argument for widget ``choices``
 ChoicesIterable = Union[Iterable[tuple[str, Any]], Iterable[Any]]
 #: An callback that can be used as a valid argument for widget ``choices``.  It takes

src/magicgui/widgets/bases/_container_widget.py

@@ -426,11 +426,13 @@
 
     def asdict(self) -> dict[str, Any]:
         """Return state of widget as dict."""
-        return {
-            w.name: getattr(w, "value", None)
-            for w in self._list
-            if w.name and not w.gui_only
-        }
+        ret = {}
+        for w in self._list:
+            if w.name and not w.gui_only:
+                ret[w.name] = getattr(w, "value", None)
+            if isinstance(w, ContainerWidget) and w.widget_type == "Container":
+                ret[w.label] = w.asdict()
+        return ret
 
     def update(
         self,