Test that we allow lazily translated strings for display values

django_enumfield/item.py

@@ -1,6 +1,7 @@
 import six
 import functools
 
+from .utils import is_lazy_translation
 from .app_settings import app_settings
 
 
@@ -34,9 +35,15 @@ def __init__(self, value, slug, display=None):
         if not isinstance(slug, str):
             raise TypeError("item slug should be a str, not %r" % type(slug))
 
-        if display is not None and not isinstance(display, six.string_types):
-            raise TypeError("item display name should be a basestring, not %r" \
-                % type(display))
+        if (
+            display is not None and
+            not isinstance(display, six.string_types) and
+            not is_lazy_translation(display)
+        ):
+            raise TypeError(
+                "item display name should be a string or lazily evaluated "
+                "string, not %r" % type(display),
+            )
 
         self.value = value
         self.slug = slug

django_enumfield/utils.py

@@ -1,4 +1,7 @@
+import six
+
 from django.http import Http404
+from django.utils.functional import Promise
 
 def get_enum_or_404(enum, slug):
     try:
@@ -25,3 +28,14 @@ def __getitem__(self, key):
 
 class TemplateErrorException(RuntimeError):
     silent_variable_failure = False
+
+def is_lazy_translation(obj):
+    # There's no public API to figure out the type of a "Promise"/"__proxy__"
+    # object, so we look at whether the object has a string type in its set
+    # of resultclasses. We do this so that we don't have to force the lazy
+    # object as that may be expensive and we're likely working at import time.
+    if not isinstance(obj, Promise):
+        return False
+
+    resultclasses = obj.__reduce__()[1][3:]
+    return any(issubclass(x, six.string_types) for x in resultclasses)

tests/tests.py

@@ -9,6 +9,7 @@
 from django.template import RequestContext
 from django.template.loader import render_to_string
 from django.db.models.fields import NOT_PROVIDED
+from django.utils.translation import gettext_lazy as _
 
 from django_enumfield import Enum, Item, get_enum_or_404
 from django_enumfield.utils import TemplateErrorException
@@ -68,6 +69,10 @@ def test_comparison(self):
         self.assertGreater(item2, item1)
         self.assertGreaterEqual(item2, item2_copy)
         self.assertLessEqual(item2, item2_copy)
+
+    def test_lazy_translation_in_display(self):
+        item = Item(10, 'slug', _("Display"))
+        self.assertEqual(item.display, "Display")
 
 
 class EnumConstructionTests(unittest.TestCase):