fix: add get_value() convenience function

src/wuttjamaican/app.py

@@ -38,6 +38,7 @@ from webhelpers2.html import HTML
 
 from wuttjamaican.util import (
     get_timezone_by_name,
+    get_value,
     localtime,
     load_entry_points,
     load_object,
@@ -374,6 +375,22 @@ class AppHandler:  # pylint: disable=too-many-public-methods
             self.__dict__["enum"] = importlib.import_module(spec)
         return self.enum
 
+    def get_value(self, obj, key):
+        """
+        Convenience wrapper around
+        :func:`wuttjamaican.util.get_value()`.
+
+        :param obj: Arbitrary dict or object of any kind which would
+           have named attributes.
+
+        :param key: Key/name of the field to get.
+
+        :returns: Whatever value is found.  Or maybe an
+           ``AttributeError`` is raised if the object does not have
+           the key/attr set.
+        """
+        return get_value(obj, key)
+
     def load_object(self, spec):
         """
         Import and/or load and return the object designated by the

src/wuttjamaican/db/util.py

@@ -56,7 +56,8 @@ class ModelBase:  # pylint: disable=empty-docstring
 
     def __iter__(self):
         # nb. we override this to allow for `dict(self)`
-        # nb. this does *not* include association proxy values
+        # nb. this does *not* include association proxy values;
+        # see also wuttjamaican.util.get_value()
         state = sa.inspect(self)
         fields = [attr.key for attr in state.attrs]
         return iter([(field, getattr(self, field)) for field in fields])

src/wuttjamaican/util.py

@@ -82,6 +82,34 @@ def get_class_hierarchy(klass, topfirst=True):
     return hierarchy
 
 
+def get_value(obj, key):
+    """
+    Convenience function to retrive a value by name from the given
+    object.  This will first try to assume the object is a dict but
+    will fallback to using ``getattr()`` on it.
+
+    :param obj: Arbitrary dict or object of any kind which would have
+       named attributes.
+
+    :param key: Key/name of the field to get.
+
+    :returns: Whatever value is found.  Or maybe an ``AttributeError``
+       is raised if the object does not have the key/attr set.
+    """
+    # nb. we try dict access first, since wutta data model objects
+    # should all support that anyway, so it's 2 birds 1 stone.
+    try:
+        return obj[key]
+
+    except (KeyError, TypeError):
+        # nb. key error means the object supports key lookup (i.e. is
+        # dict-like) but did not have that key set.  which is actually
+        # an expected scenario for association proxy fields, but for
+        # those a getattr() should still work; see also
+        # wuttjamaican.db.util.ModelBase
+        return getattr(obj, key)
+
+
 def load_entry_points(group, ignore_errors=False):
     """
     Load a set of ``setuptools``-style entry points.

tests/test_app.py

@@ -48,6 +48,32 @@ class TestAppHandler(FileTestCase):
     def test_get_enum(self):
         self.assertIs(self.app.get_enum(), wuttjamaican.enum)
 
+    def test_get_value(self):
+
+        class Object:
+            def __init__(self, **kw):
+                self.__dict__.update(kw)
+
+        class Dict(dict):
+            pass
+
+        # dict object
+        obj = {"foo": "bar"}
+        self.assertEqual(self.app.get_value(obj, "foo"), "bar")
+
+        # object w/ attrs
+        obj = Object(foo="bar")
+        self.assertEqual(self.app.get_value(obj, "foo"), "bar")
+
+        # dict-like w/ attrs
+        obj = Dict({"foo": "bar"})
+        obj.baz = "yyy"
+        self.assertEqual(self.app.get_value(obj, "baz"), "yyy")
+
+        # missing attr
+        obj = Object(foo="bar")
+        self.assertRaises(AttributeError, self.app.get_value, obj, "baz")
+
     def test_load_object(self):
 
         # just confirm the method works on a basic level; the

tests/test_util.py

@@ -41,6 +41,35 @@ class TestGetClassHierarchy(TestCase):
         self.assertEqual(classes, [C, B, A])
 
 
+class TestGetValue(TestCase):
+
+    def test_basic(self):
+
+        class Object:
+            def __init__(self, **kw):
+                self.__dict__.update(kw)
+
+        class Dict(dict):
+            pass
+
+        # dict object
+        obj = {"foo": "bar"}
+        self.assertEqual(mod.get_value(obj, "foo"), "bar")
+
+        # object w/ attrs
+        obj = Object(foo="bar")
+        self.assertEqual(mod.get_value(obj, "foo"), "bar")
+
+        # dict-like w/ attrs
+        obj = Dict({"foo": "bar"})
+        obj.baz = "yyy"
+        self.assertEqual(mod.get_value(obj, "baz"), "yyy")
+
+        # missing attr
+        obj = Object(foo="bar")
+        self.assertRaises(AttributeError, mod.get_value, obj, "baz")
+
+
 class TestLoadEntryPoints(TestCase):
 
     def test_empty(self):