Limit uuslug max_length to the field max_length

uuslug/models.py

@@ -82,3 +82,17 @@ if 'testsettings' in os.environ['DJANGO_SETTINGS_MODULE']:
         def save(self, *args, **kwargs):
             self.slug = uuslug(self.name, instance=self, start_no=2, max_length=17, word_boundary=False, separator='_')
             super(TruncatedSlugDifferentSeparator, self).save(*args, **kwargs)
+
+    class SmallSlug(models.Model):
+        """
+        The slug by generated by uuslug is bigger than the field max_length
+        """
+        name = models.CharField(max_length=20)
+        slug = models.CharField(max_length=10)
+
+        def __unicode__(self):
+            return self.name
+
+        def save(self, *args, **kwargs):
+            self.slug = uuslug(self.name, instance=self, max_length=20)
+            super(SmallSlug, self).save(*args, **kwargs)

uuslug/tests/tests.py

@@ -8,7 +8,8 @@ from django.test import TestCase
 from uuslug import slugify
 from uuslug.models import (CoolSlug, AnotherSlug, TruncatedSlug,
                            SmartTruncatedSlug, SmartTruncatedExactWordBoundrySlug,
-                           CoolSlugDifferentSeparator, TruncatedSlugDifferentSeparator)
+                           CoolSlugDifferentSeparator, TruncatedSlugDifferentSeparator,
+                           SmallSlug)
 
 
 class SlugUnicodeTestCase(TestCase):
@@ -218,3 +219,29 @@ class SlugUniqueDifferentSeparatorTestCase(TestCase):
 
         obj = TruncatedSlugDifferentSeparator.objects.create(name=name)
         self.assertEqual(obj.slug, "jaja_lol_mememe_3")  # 17 is max_length
+
+
+class SlugMaxLengthTestCase(TestCase):
+    """Tests for Slug - Max length minor than field length"""
+
+    def test_manager(self):
+        name = "john" * 51
+
+        with self.assertNumQueries(2):
+            obj = CoolSlug.objects.create(name=name)
+        self.assertEqual(obj.slug, name[:200])
+
+        with self.assertNumQueries(3):
+            obj = CoolSlug.objects.create(name=name)
+        self.assertEqual(obj.slug, name[:198] + "-1")
+
+    def test_max_length_bigger_than_field_slug(self):
+        name = 'jaja---lol-méméméoo--a-méméméoo'
+
+        obj = SmallSlug.objects.create(name=name)
+        # 10 is field max_length, 20 is uuslug function max_length
+        self.assertEqual(obj.slug, "jaja-lol-m")
+
+        # 10 is field max_length, 20 is uuslug function max_length
+        obj = SmallSlug.objects.create(name=name)
+        self.assertEqual(obj.slug, "jaja-lol-1")

uuslug/uuslug.py

@@ -33,6 +33,11 @@ def uuslug(s, instance, entities=True, decimal=True, hexadecimal=True,
     if instance.pk:
         queryset = queryset.exclude(pk=instance.pk)
 
+    # The slug max_length cannot be bigger than the max length of the field
+    slug_field_max_length = instance._meta.get_field(slug_field).max_length
+    if not max_length or max_length > slug_field_max_length:
+        max_length = slug_field_max_length
+
     slug = slugify(s, entities=entities, decimal=decimal, hexadecimal=hexadecimal,
                    max_length=max_length, word_boundary=word_boundary, separator=separator,
                    save_order=save_order)