Merge pull request #76 from NextThought/better-anon-fallback

Look for IInternalObjectIO adapters as well as INamedExternalizedObje…

CHANGES.rst

@@ -6,7 +6,13 @@
 1.0.0a5 (unreleased)
 ====================
 
-- Nothing changed yet.
+- Objects inheriting from ``InterfaceObjectIO`` and registered with
+  the component registry (in ZCML) for ``IInternalObjectIO`` can still
+  be found and used as ``INamedExternalizedObjectFactoryFinder``, an
+  interface implemented by ``InterfaceObjectIO`` through
+  ``IInternalObjectIOFinder``. A warning will be issued to update the
+  registration (which generally means removing the ``provides`` line
+  in ZCML).
 
 - ``ExternalizableInstanceDict`` no longer inherits from
   ``AbstractDynamicIO``, it just implements the same interface (with

src/nti/externalization/internalization/_updater.pxd

@@ -16,6 +16,7 @@ cdef iteritems
 cdef component
 cdef interface
 cdef IInternalObjectUpdater
+cdef IInternalObjectIO
 cdef INamedExternalizedObjectFactoryFinder
 
 # optimizations
@@ -53,6 +54,7 @@ cdef _invoke_updater(containedObject, externalObject, updater,
 cdef _update_sequence(externalObject, _RecallArgs args,
                       destination_name=*,
                       find_factory_for_named_value=*)
+cpdef _find_INamedExternalizedObjectFactoryFinder(containedObject, registry)
 cdef _update_from_external_object(containedObject, externalObject, _RecallArgs args)
 
 cpdef update_from_external_object(containedObject,

src/nti/externalization/internalization/tests/test_externals_wo_class_mimetype.py

@@ -17,6 +17,8 @@
 from hamcrest import is_
 from hamcrest import assert_that
 from hamcrest import has_property as has_attr
+from hamcrest import has_length
+from hamcrest import contains_string
 
 from zope import interface
 from zope import component
@@ -27,7 +29,9 @@
 
 from zope.testing.cleanup import CleanUp
 
+from nti.externalization import interfaces
 from nti.externalization.internalization import update_from_external_object
+from nti.externalization.internalization import updater
 from nti.externalization.datastructures import InterfaceObjectIO
 
 
@@ -214,6 +218,27 @@ def test_nested_single_object_field_names_match_non_primitive_zcml(self):
         assert_that(root.field, has_attr('nested', has_attr('value', 42)))
 
 
+class TestLookups(CleanUp,
+                  unittest.TestCase):
+
+    def test_InterfaceObjectIO_subclass_registered_as_IInternalObjectIO(self):
+        # We still find it even if it's registered with the legacy interface.
+        import warnings
+
+        class Derived(InterfaceObjectIO):
+            def __init__(self, context): # pylint:disable=super-init-not-called
+                pass
+
+        component.provideAdapter(Derived, (object,), provides=interfaces.IInternalObjectIO)
+
+        with warnings.catch_warnings(record=True) as w:
+            found = updater._find_INamedExternalizedObjectFactoryFinder(self, component)
+
+        assert_that(found, is_(Derived))
+        assert_that(w, has_length(1))
+        assert_that(str(w[0].message), contains_string('was registered as IInternalObjectIO'))
+
+
 class IOBase(object):
 
     @classmethod

src/nti/externalization/internalization/updater.py

@@ -29,6 +29,7 @@
 
 from nti.externalization._base_interfaces import PRIMITIVES
 from nti.externalization.interfaces import IInternalObjectUpdater
+from nti.externalization.interfaces import IInternalObjectIO
 from nti.externalization.interfaces import INamedExternalizedObjectFactoryFinder
 
 from .factories import find_factory_for
@@ -287,6 +288,29 @@ def _invoke_updater(containedObject, externalObject,
                         updater, external_keys, _EMPTY_DICT)
 
 
+def _find_INamedExternalizedObjectFactoryFinder(containedObject, registry):
+    updater = registry.queryAdapter(containedObject, INamedExternalizedObjectFactoryFinder)
+    if updater is None:
+        # Ok, check to see if an instance of the old root interface
+        # InternalObjectIO is there and also provides INamedExternalizedObjectFactoryFinder;
+        # if so, there's a bad ZCML registration.
+        updater = registry.queryAdapter(containedObject, IInternalObjectIO)
+        if INamedExternalizedObjectFactoryFinder.providedBy(updater):
+            warnings.warn(
+                "The adapter %r was registered as IInternalObjectIO when it should be "
+                "IInternalObjectIOFinder; a provides= ZCML directive is probably outdated. "
+                "If the object extends InterfacObjectIO, no provides= is usually necessary."
+                % (updater,),
+                UserWarning
+            )
+        else:
+            updater = None
+
+    if updater is None:
+        updater = _default_factory_finder
+    return updater
+
+
 def _update_from_external_object(containedObject, externalObject, args):
 
     # Parse any contained objects
@@ -309,8 +333,8 @@ def _update_from_external_object(containedObject, externalObject, args):
 
     assert isinstance(externalObject, MutableMapping)
 
-    updater = args.registry.queryAdapter(containedObject, INamedExternalizedObjectFactoryFinder,
-                                         u'', _default_factory_finder)
+    updater = _find_INamedExternalizedObjectFactoryFinder(containedObject, args.registry)
+
     find_factory_for_named_value = updater.find_factory_for_named_value
 
     # We have to save the list of keys, it's common that they get popped during the update