Look up widgets for fields implementing IChoice by querying for an ad…

…apter for (field, field.vocabulary, request) instead of just (field, request), so it can be differentiated according to the type of the source used for the field. (Inspired by how zope.formlib handles the same case.)

--This line, and those below, will
  be ignored--

M    CHANGES.txt
M    src/z3c/form/browser/select.zcml
M    src/z3c/form/browser/tests.py
M    src/z3c/form/browser/select.py
A    src/z3c/form/browser/select-source.txt
M    src/z3c/form/testing.py

CHANGES.txt

@@ -107,6 +107,9 @@ Version 2.0.0 (unreleased)
 - Bug: SingleCheckBoxFieldWidget doesn't repeat the label twice (once in
   <div class="label">, and once in the <label> next to the checkbox).
 
+- Feature: The widget for fields implementing IChoice is now looked up by
+  querying for an adapter for (field, field.vocabulary, request) so it can be
+  differentiated according to the type of the source used for the field.
 
 Version 1.9.0 (2008-08-26)
 --------------------------

src/z3c/form/browser/select-source.txt

@@ -0,0 +1,72 @@
+=====================================
+Customizing widget lookup for IChoice
+=====================================
+
+Widgets for fields implementing IChoice are looked up not only according to the
+field, but also according to the source used by the field.
+
+  >>> import z3c.form.testing
+  >>> import zope.interface
+  >>> import zope.component
+  >>> from z3c.form import interfaces
+  >>> from z3c.form.testing import TestRequest
+
+  >>> z3c.form.testing.setupFormDefaults()
+  >>> def setupWidget(field):
+  ...     request = TestRequest()
+  ...     widget = zope.component.getMultiAdapter((field, request),
+  ...         interfaces.IFieldWidget)
+  ...     widget.id = 'foo'
+  ...     widget.name = 'bar'
+  ...     return widget
+
+We define a sample field and source:
+
+  >>> from zope.schema import vocabulary
+  >>> terms = [vocabulary.SimpleTerm(*value) for value in
+  ...          [(True, 'yes', 'Yes'), (False, 'no', 'No')]]
+  >>> vocabulary = vocabulary.SimpleVocabulary(terms)
+  >>> field = zope.schema.Choice(default=True, vocabulary=vocabulary)
+
+The default widget is the SelectWidget:
+
+  >>> widget = setupWidget(field)
+  >>> type(widget)
+  <class 'z3c.form.browser.select.SelectWidget'>
+
+But now we define a marker interface and have our source provide it:
+
+  >>> from z3c.form.widget import FieldWidget
+  >>> class ISampleSource(zope.interface.Interface):
+  ...     pass
+  >>> zope.interface.alsoProvides(vocabulary, ISampleSource)
+
+We can then create and register a special widget for fields using sources with
+the ISampleSource marker:
+
+  >>> class SampleSelectWidget(z3c.form.browser.select.SelectWidget):
+  ...     pass
+  >>> def SampleSelectFieldWidget(field, source, request):
+  ...     return FieldWidget(field, SampleSelectWidget(request))
+  >>> zope.component.provideAdapter(
+  ...   SampleSelectFieldWidget,
+  ...   (zope.schema.interfaces.IChoice, ISampleSource, interfaces.IFormLayer),
+  ...   interfaces.IFieldWidget)
+
+If we now look up the widget for the field, we get the specialized widget:
+
+  >>> widget = setupWidget(field)
+  >>> type(widget)
+  <class 'SampleSelectWidget'>
+
+Backwards compatibility
+-----------------------
+
+To maintain backwards compatibility, SelectFieldWidget() still can be called
+without passing a source:
+
+  >>> import z3c.form.browser.select
+  >>> request = TestRequest()
+  >>> widget = z3c.form.browser.select.SelectFieldWidget(field, request)
+  >>> type(widget)
+  <class 'z3c.form.browser.select.SelectWidget'>

src/z3c/form/browser/select.py

@@ -75,9 +75,25 @@ def update(self):
 
 @zope.component.adapter(zope.schema.interfaces.IChoice, interfaces.IFormLayer)
 @zope.interface.implementer(interfaces.IFieldWidget)
-def SelectFieldWidget(field, request):
+def ChoiceWidgetDispatcher(field, request):
+    """Dispatch widget for IChoice based also on its source."""
+    return zope.component.getMultiAdapter((field, field.vocabulary, request),
+                                          interfaces.IFieldWidget)
+
+
+# IBaseVocabulary can change to ISource once vocabularies are deprecated
+@zope.component.adapter(zope.schema.interfaces.IChoice,
+                        zope.schema.interfaces.IBaseVocabulary,
+                        interfaces.IFormLayer)
+@zope.interface.implementer(interfaces.IFieldWidget)
+def SelectFieldWidget(field, source, request=None):
     """IFieldWidget factory for SelectWidget."""
-    return FieldWidget(field, SelectWidget(request))
+    # BBB: emulate our pre-2.0 signature (field, request)
+    if request is None:
+        real_request = source
+    else:
+        real_request = request
+    return FieldWidget(field, SelectWidget(real_request))
 
 
 @zope.component.adapter(
@@ -98,4 +114,4 @@ def CollectionSelectFieldWidget(field, request):
 @zope.interface.implementer(interfaces.IFieldWidget)
 def CollectionChoiceSelectFieldWidget(field, value_type, request):
     """IFieldWidget factory for SelectWidget."""
-    return SelectFieldWidget(field, request)
+    return SelectFieldWidget(field, None, request)

src/z3c/form/browser/select.zcml

@@ -10,6 +10,10 @@
         />
   </class>
 
+  <adapter
+      factory=".select.ChoiceWidgetDispatcher"
+      />
+
   <adapter
       factory=".select.SelectFieldWidget"
       />

src/z3c/form/browser/tests.py

@@ -71,6 +71,11 @@ def test_suite():
                      optionflags=doctest.NORMALIZE_WHITESPACE|doctest.ELLIPSIS,
                      checker=checker,
                      ),
+        DocFileSuite('select-source.txt',
+                     setUp=setUp, tearDown=testing.tearDown,
+                     optionflags=doctest.NORMALIZE_WHITESPACE|doctest.ELLIPSIS,
+                     checker=checker,
+                     ),
         DocFileSuite('submit.txt',
                      setUp=setUp, tearDown=testing.tearDown,
                      optionflags=doctest.NORMALIZE_WHITESPACE|doctest.ELLIPSIS,

src/z3c/form/testing.py

@@ -281,6 +281,7 @@ def setupFormDefaults():
         IPageTemplate, name=interfaces.DISPLAY_MODE)
 
     # Select Widget
+    zope.component.provideAdapter(select.ChoiceWidgetDispatcher)
     zope.component.provideAdapter(select.SelectFieldWidget)
     zope.component.provideAdapter(
         widget.WidgetTemplateFactory(getPath('select_input.pt'), 'text/html'),