added triple option in Choices to split db representation from code constant

model_utils/__init__.py

@@ -57,39 +57,70 @@ class Choices(object):
     A class to encapsulate handy functionality for lists of choices
     for a Django model field.
 
-    Accepts as arguments either tuples mapping choice IDs (strings) to
-    human-readable names, or simply choice IDs (in which case the ID
-    is also used as the human-readable name). When iterated over,
+    Each argument to ``Choices`` is a choice, represented as either a
+    string, a two-tuple, or a three-tuple.
+
+    If a single string is provided, that string is used as the
+    database representation of the choice as well as the
+    human-readable presentation.
+
+    If a two-tuple is provided, the first item is used as the database
+    representation and the second the human-readable presentation.
+
+    If a triple is provided, the first item is the database
+    representation, the second a valid Python identifier that can be
+    used as a readable label in code, and the third the human-readable
+    presentation. This is most useful when the database representation
+    must sacrifice readability for some reason: to achieve a specific
+    ordering, to use an integer rather than a character field, etc.
+
+    Regardless of what representation of each choice is originally
+    given, when iterated over or indexed into, a ``Choices`` object
     behaves as the standard Django choices list of two-tuples.
 
-    Choice IDs can be accessed as attributes for readable code.
+    If the triple form is used, the Python identifier names can be
+    accessed as attributes on the ``Choices`` object, returning the
+    database representation. (If the single or two-tuple forms are
+    used and the database representation happens to be a valid Python
+    identifier, the database representation itself is available as an
+    attribute on the ``Choices`` object, returning itself.)
 
     """
 
     def __init__(self, *choices):
-        self._choices = list(self.equalize(choices))
-        self._choice_dict = dict(self._choices)
-        self._reverse_dict = dict(((i[0], i[0]) for i in self._choices))
+        self._full = []
+        self._choices = []
+        self._choice_dict = {}
+        for choice in self.equalize(choices):
+            self._full.append(choice)
+            self._choices.append((choice[0], choice[2]))
+            self._choice_dict[choice[1]] = choice[0]
 
     def equalize(self, choices):
         for choice in choices:
             if isinstance(choice, (list, tuple)):
-                yield choice
+                if len(choice) == 3:
+                    yield choice
+                elif len(choice) == 2:
+                    yield (choice[0], choice[0], choice[1])
+                else:
+                    raise ValueError("Choices can't handle a list/tuple of length %s, only 2 or 3"
+                                     % len(choice))
             else:
-                yield (choice, choice)
+                yield (choice, choice, choice)
 
     def __iter__(self):
         return iter(self._choices)
 
     def __getattr__(self, attname):
         try:
-            return self._reverse_dict[attname]
+            return self._choice_dict[attname]
         except KeyError:
-            raise AttributeError(attname)
-
+            raise AttributeError(attname)    
+    
     def __getitem__(self, index):
         return self._choices[index]
 
     def __repr__(self):
         return '%s(%s)' % (self.__class__.__name__,
-                          ', '.join(("'%s'" % i[0] for i in self._choices)))
+                          ', '.join(("%s" % str(i) for i in self._full)))

model_utils/tests/tests.py

@@ -111,6 +111,12 @@ class ChoicesTests(TestCase):
     def test_iteration(self):
         self.assertEquals(tuple(self.STATUS), (('DRAFT', 'DRAFT'), ('PUBLISHED', 'PUBLISHED')))
 
+    def test_repr(self):
+        self.assertEquals(repr(self.STATUS),
+                          "Choices("
+                          "('DRAFT', 'DRAFT', 'DRAFT'), "
+                          "('PUBLISHED', 'PUBLISHED', 'PUBLISHED'))")
+
         
 class LabelChoicesTests(ChoicesTests):
     def setUp(self):
@@ -136,7 +142,41 @@ class LabelChoicesTests(ChoicesTests):
     def test_provided(self):
         self.assertEquals(self.STATUS.DRAFT, 'DRAFT')
 
+    def test_repr(self):
+        self.assertEquals(repr(self.STATUS),
+                          "Choices("
+                          "('DRAFT', 'DRAFT', 'is draft'), "
+                          "('PUBLISHED', 'PUBLISHED', 'is published'), "
+                          "('DELETED', 'DELETED', 'DELETED'))")
 
+        
+class IdentifierChoicesTests(ChoicesTests):
+    def setUp(self):
+        self.STATUS = Choices(
+            (0, 'DRAFT', 'is draft'),
+            (1, 'PUBLISHED', 'is published'),
+            (2, 'DELETED', 'is deleted'))
+
+    def test_iteration(self):
+        self.assertEqual(tuple(self.STATUS), (
+                (0, 'is draft'),
+                (1, 'is published'),
+                (2, 'is deleted')))
+
+    def test_indexing(self):
+        self.assertEquals(self.STATUS[1], (1, 'is published'))
+
+    def test_getattr(self):
+        self.assertEquals(self.STATUS.DRAFT, 0)
+        
+    def test_repr(self):
+        self.assertEquals(repr(self.STATUS),
+                          "Choices("
+                          "(0, 'DRAFT', 'is draft'), "
+                          "(1, 'PUBLISHED', 'is published'), "
+                          "(2, 'DELETED', 'is deleted'))")
+
+        
 class InheritanceCastModelTests(TestCase):
     def setUp(self):
         self.parent = InheritParent.objects.create()