Fixes bigjason#47 -- add public api to get attribute name from value

djchoices/choices.py

@@ -34,8 +34,25 @@ def __init__(self, value):
     def __get__(self, obj, objtype):
         return self.value
 
+
+class Attributes(object):
+
+    def __init__(self, attrs, fields):
+        self.attrs = attrs
+        self.fields = fields
+
+    def __get__(self, obj, objtype):
+        if len(self.attrs) != len(self.fields):
+            raise ValueError(
+                'Not all values are unique, it\'s not possible to map all '
+                'values to the right attribute'
+            )
+        return self.attrs
+
+
 # End Support Functionality
 
+
 sentinel = object()
 
 
@@ -73,6 +90,7 @@ def __new__(cls, name, bases, attrs):
         fields = {}
         labels = Labels()
         values = OrderedDict()
+        attributes = OrderedDict()
         choices = []
 
         # Get all the fields from parent classes.
@@ -103,6 +121,7 @@ def __new__(cls, name, bases, attrs):
                 attrs[field_name] = StaticProp(val0)
                 setattr(labels, field_name, label)
                 values[val0] = label
+                attributes[val0] = field_name
             else:
                 choices.append((field_name, val.choices))
 
@@ -111,6 +130,7 @@ def __new__(cls, name, bases, attrs):
         attrs["values"] = values
         attrs["_fields"] = fields
         attrs["validator"] = ChoicesValidator(values)
+        attrs["attributes"] = Attributes(attributes, fields)
 
         return super(DjangoChoicesMeta, cls).__new__(cls, name, bases, attrs)
 

djchoices/tests/test_choices.py

@@ -39,6 +39,11 @@ class NullBooleanValueClass(DjangoChoices):
     Option3 = ChoiceItem(False, "Failed")
 
 
+class DuplicateValuesClass(DjangoChoices):
+    Option1 = ChoiceItem('a')
+    Option2 = ChoiceItem('a')
+
+
 class DjangoChoices(unittest.TestCase):
     def setUp(self):
         pass
@@ -183,3 +188,14 @@ def test_deconstructible_validator(self):
         self.assertEqual(deconstructed, (
             'djchoices.choices.ChoicesValidator', (NumericTestClass.values,), {}
         ))
+
+    def test_attribute_from_value(self):
+        attributes = NumericTestClass.attributes
+        self.assertEqual(attributes[0], 'Item_0')
+        self.assertEqual(attributes[1], 'Item_1')
+        self.assertEqual(attributes[2], 'Item_2')
+        self.assertEqual(attributes[3], 'Item_3')
+
+    def test_attribute_from_value_duplicates(self):
+        with self.assertRaises(ValueError):
+            DuplicateValuesClass.attributes