Fix traversing to widgets nested in an object widget

news/29.bugfix.rst

@@ -0,0 +1 @@
+Fix traversing to widgets nested in an object widget [ale-rt]

src/plone/z3cform/traversal.py

@@ -4,6 +4,7 @@
 from plone.z3cform.interfaces import IDeferSecurityCheck
 from plone.z3cform.interfaces import IFormWrapper
 from z3c.form import util
+from z3c.form.browser.object import ObjectWidget
 from z3c.form.interfaces import IForm
 from zope.component import adapter
 from zope.interface import alsoProvides
@@ -86,6 +87,14 @@ def traverse(self, name, ignored):
                         parts.remove("widgets")
                     else:
                         raise TraversalError("'" + part + "' not valid index")
+            elif isinstance(target, ObjectWidget):
+                # ObjectWidget is a special case, we need to look for
+                # the name in the widget list
+                try:
+                    name = parts.pop(0)
+                    target = target.widgets[name]
+                except (IndexError, KeyError):
+                    target = None
             elif hasattr(target, "widgets"):  # Either base form, or subform
                 # Check to see if we can find a "Behaviour.widget"
                 new_target = None

src/plone/z3cform/traversal.txt

@@ -211,16 +211,33 @@ We can find this object widget
     >>> obj_widget
     <ObjectWidget 'form.widgets.obj_field'>
 
-And traverse through to the form within
+We initialize the traverses to the form within:
 
     >>> traverser = get_traverser(Bar(),u"test-parent-form")
-    >>> list_widget = traverser.traverse('obj_field.list_field', [])
+
+The form is the traverser context:
+    >>> traverser.context.__class__
+    <class 'MyParentForm'>
+
+We want to traverse to the list_field widget within the object field:
+    >>> traverser.context.update()
+    Updating test form
+    >>> list_field_widget = traverser.context.widgets["obj_field"].widgets["list_field"]
+    >>> list_field_widget
+    <MultiWidget 'form.widgets.obj_field.widgets.list_field'>
+
+The widget as a prefix:
+    >>> list_field_widget.prefix
+    'form.widgets.obj_field.widgets.list_field'
+
+To traverse to it we need to remove the form and widgets prefixes:
+    >>> list_widget = traverser.traverse('obj_field.widgets.list_field', [])
     Updating test form
     >>> list_widget
     <MultiWidget 'form.widgets.obj_field.widgets.list_field'>
 
     >>> traverser = get_traverser(Bar(),u"test-parent-form")
-    >>> age_widget = traverser.traverse('obj_field.list_field.0', [])
+    >>> age_widget = traverser.traverse('obj_field.widgets.list_field.0', [])
     Updating test form
     >>> age_widget
     <TextWidget 'form.widgets.obj_field.widgets.list_field.0'>
@@ -230,10 +247,10 @@ And traverse through to the form within
 Missing widgets are LocationErrors
 
     >>> traverser = get_traverser(Bar(),u"test-parent-form")
-    >>> list_widget = traverser.traverse('obj_field.camel_field', [])
+    >>> list_widget = traverser.traverse('obj_field.widgets.camel_field', [])
     Traceback (most recent call last):
       File "<stdin>", line 1, in ?
-    zope.location.interfaces.LocationError: 'camel_field'
+    zope.location.interfaces.LocationError: 'widgets'
 
 Looking for anything other than 'widgets' is also an error