fix: add way to set field widgets using pseudo-type

more to come on this idea hopefully..i think it's a good pattern?

src/wuttaweb/forms/base.py

@@ -457,23 +457,62 @@ class Form:
         if self.schema:
             self.schema[key] = node
 
-    def set_widget(self, key, widget):
+    def set_widget(self, key, widget, **kwargs):
         """
         Set/override the widget for a field.
 
+        You can specify a widget instance or else a named "type" of
+        widget, in which case that is passed along to
+        :meth:`make_widget()`.
+
         :param key: Name of field.
 
-        :param widget: Instance of
+        :param widget: Either a :class:`deform:deform.widget.Widget`
-           :class:`deform:deform.widget.Widget`.
+           instance, or else a widget "type" name.
+
+        :param \**kwargs: Any remaining kwargs are passed along to
+           :meth:`make_widget()` - if applicable.
 
         Widget overrides are tracked via :attr:`widgets`.
         """
+        if not isinstance(widget, deform.widget.Widget):
+            widget_obj = self.make_widget(widget, **kwargs)
+            if not widget_obj:
+                raise ValueError(f"widget type not supported: {widget}")
+            widget = widget_obj
+
         self.widgets[key] = widget
 
         # update schema if necessary
         if self.schema and key in self.schema:
             self.schema[key].widget = widget
 
+    def make_widget(self, widget_type, **kwargs):
+        """
+        Make and return a new field widget of the given type.
+
+        This has built-in support for the following types (although
+        subclass can override as needed):
+
+        * ``'notes'`` => :class:`~wuttaweb.forms.widgets.NotesWidget`
+
+        See also :meth:`set_widget()` which may call this method
+        automatically.
+
+        :param widget_type: Which of the above (or custom) widget
+           type to create.
+
+        :param \**kwargs: Remaining kwargs are passed as-is to the
+           widget factory.
+
+        :returns: New widget instance, or ``None`` if e.g. it could
+           not determine how to create the widget.
+        """
+        from wuttaweb.forms import widgets
+
+        if widget_type == 'notes':
+            return widgets.NotesWidget(**kwargs)
+
     def set_grid(self, key, grid):
         """
         Establish a :term:`grid` to be displayed for a field.  This

src/wuttaweb/views/upgrades.py

@@ -34,7 +34,6 @@ from sqlalchemy import orm
 
 from wuttjamaican.db.model import Upgrade
 from wuttaweb.views import MasterView
-from wuttaweb.forms import widgets
 from wuttaweb.forms.schema import UserRef, WuttaEnum, FileDownload
 from wuttaweb.progress import get_progress_session
 
@@ -147,7 +146,7 @@ class UpgradeView(MasterView):
             f.set_node('created_by', UserRef(self.request))
 
         # notes
-        f.set_widget('notes', widgets.NotesWidget())
+        f.set_widget('notes', 'notes')
 
         # status
         if self.creating:

tests/forms/test_base.py

@@ -142,6 +142,26 @@ class TestForm(TestCase):
         self.assertIs(form.widgets['foo'], new_widget)
         self.assertIs(schema['foo'].widget, new_widget)
 
+        # can also just specify widget pseudo-type (invalid)
+        self.assertNotIn('bar', form.widgets)
+        self.assertRaises(ValueError, form.set_widget, 'bar', 'ldjfadjfadj')
+
+        # can also just specify widget pseudo-type (valid)
+        self.assertNotIn('bar', form.widgets)
+        form.set_widget('bar', 'notes')
+        self.assertIsInstance(form.widgets['bar'], widgets.NotesWidget)
+
+    def test_make_widget(self):
+        form = self.make_form(fields=['foo', 'bar'])
+
+        # notes
+        widget = form.make_widget('notes')
+        self.assertIsInstance(widget, widgets.NotesWidget)
+
+        # invalid
+        widget = form.make_widget('fdajvdafjjf')
+        self.assertIsNone(widget)
+
     def test_set_grid(self):
         form = self.make_form(fields=['foo', 'bar'])
         self.assertNotIn('foo', form.widgets)