Add min_value=0 to autogenerated Pos..IntFields

rest_framework/serializers.py

@@ -739,6 +739,10 @@ class ModelSerializer(Serializer):
         if issubclass(model_field.__class__, models.TextField):
             kwargs['widget'] = widgets.Textarea
 
+        if issubclass(model_field.__class__, models.PositiveIntegerField) or\
+                issubclass(model_field.__class__, models.PositiveSmallIntegerField):
+            kwargs['min_value'] = 0
+
         # TODO: TypedChoiceField?
         if model_field.flatchoices:  # This ModelField contains choices
             kwargs['choices'] = model_field.flatchoices

rest_framework/tests/serializer.py

@@ -1402,3 +1402,76 @@ class AttributeMappingOnAutogeneratedFieldsTests(TestCase):
 
     def test_url_field(self):
         self.field_test('url_field')
+
+
+class DefaultValuesOnAutogeneratedFieldsTests(TestCase):
+
+    def setUp(self):
+        class DVOAFModel(RESTFrameworkModel):
+            positive_integer_field = models.PositiveIntegerField(blank=True)
+            positive_small_integer_field = models.PositiveSmallIntegerField(blank=True)
+            email_field = models.EmailField(blank=True)
+            file_field = models.FileField(blank=True)
+            image_field = models.ImageField(blank=True)
+            slug_field = models.SlugField(blank=True)
+            url_field = models.URLField(blank=True)
+
+        class DVOAFSerializer(serializers.ModelSerializer):
+            class Meta:
+                model = DVOAFModel
+
+        self.serializer_class = DVOAFSerializer
+        self.fields_attributes = {
+            'positive_integer_field': [
+                ('min_value', 0),
+            ],
+            'positive_small_integer_field': [
+                ('min_value', 0),
+            ],
+            'email_field': [
+                ('max_length', 75),
+            ],
+            'file_field': [
+                ('max_length', 100),
+            ],
+            'image_field': [
+                ('max_length', 100),
+            ],
+            'slug_field': [
+                ('max_length', 50),
+            ],
+            'url_field': [
+                ('max_length', 200),
+            ],
+        }
+
+    def field_test(self, field):
+        serializer = self.serializer_class(data={})
+        self.assertEqual(serializer.is_valid(), True)
+
+        for attribute in self.fields_attributes[field]:
+            self.assertEqual(
+                getattr(serializer.fields[field], attribute[0]),
+                attribute[1]
+            )
+
+    def test_positive_integer_field(self):
+        self.field_test('positive_integer_field')
+
+    def test_positive_small_integer_field(self):
+        self.field_test('positive_small_integer_field')
+
+    def test_email_field(self):
+        self.field_test('email_field')
+
+    def test_file_field(self):
+        self.field_test('file_field')
+
+    def test_image_field(self):
+        self.field_test('image_field')
+
+    def test_slug_field(self):
+        self.field_test('slug_field')
+
+    def test_url_field(self):
+        self.field_test('url_field')