Fix field uniqueness checks

isbn_field/fields.py

@@ -38,5 +38,11 @@ def pre_save(self, model_instance, add):
             setattr(model_instance, self.attname, cleaned_isbn)
         return super(ISBNField, self).pre_save(model_instance, add)
 
+    def to_python(self, value):
+        if self.clean_isbn and value not in EMPTY_VALUES:
+            return value.replace(' ', '').replace('-', '').upper()
+        else:
+            return value
+
     def __unicode__(self):
         return self.value

tests/models.py

@@ -6,6 +6,11 @@ class CleanISBNModel(models.Model):
     isbn = ISBNField() # clean_isbn=True (default)
 
 
+class UniqueCleanISBNModel(models.Model):
+
+    isbn = ISBNField(unique=True) # clean_isbn=True (default)
+
+
 class DirtyISBNModel(models.Model):
     id = models.BigAutoField(primary_key=True)
     isbn = ISBNField(clean_isbn=False)

tests/tests.py

@@ -1,10 +1,9 @@
 from django.core.exceptions import ValidationError
-from isbn_field.validators import ISBNValidator
-from isbn_field import ISBNField
-
 from django.test import TestCase
 
-from .models import CleanISBNModel, DirtyISBNModel, BlankISBNModel, BlankNullISBNModel
+from isbn_field.validators import ISBNValidator
+from .models import CleanISBNModel, DirtyISBNModel, BlankISBNModel, BlankNullISBNModel, UniqueCleanISBNModel
+
 
 class ISBNValidatorTest(TestCase):
 
@@ -71,6 +70,17 @@ def test_isbn_field_clean(self):
             m = DirtyISBNModel.objects.create(isbn=original)
             self.assertEqual(m.isbn, original)
 
+    def test_isbn_field_unique_clean(self):
+        UniqueCleanISBNModel.objects.create(isbn='0-765-348-276')
+
+        with self.assertRaises(ValidationError):
+            instance = UniqueCleanISBNModel(isbn='0-765-348-276')
+            instance.full_clean()
+            # The previous line should throw the expected exception,
+            # but if it does not, the line below throwing an IntegrityError
+            # serves as a sanity check for this test.
+            UniqueCleanISBNModel.objects.create(isbn='0-765-348-276')
+
     def test_isbn_field_blank(self):
         """Test empty values are accepted when blank=True"""
         m = BlankISBNModel.objects.create(isbn="")