account for UniqueTogetherValidator having a code attribute starting drf 3.17

Author: ghazi-git

drf_standardized_errors/openapi_utils.py

@@ -1,6 +1,8 @@
 from dataclasses import dataclass, field as dataclass_field
 from typing import Any, Dict, List, Optional, Set, Type, Union
 
+import django
+import rest_framework
 from django import forms
 from django.core.validators import (
     DecimalValidator,
@@ -230,12 +232,18 @@ def add_unique_together_error_codes(
     sfields_with_error_codes: "List[InputDataField]",
 ) -> None:
     for sfield in sfields_with_unique_together_validators:
-        sfield.error_codes.add("unique")
         unique_together_validators = [
             validator
             for validator in sfield.field.validators
             if isinstance(validator, UniqueTogetherValidator)
         ]
+        if _drf_version() >= (3, 17) and django.VERSION >= (5, 0):
+            # drf 3.17 passes the `custom_violation_error` added in django 5.0
+            # to `drf.UniqueTogetherValidator`. Before that, the error code was
+            # hardcoded as `"unique"`
+            sfield.error_codes.update(v.code for v in unique_together_validators)
+        else:
+            sfield.error_codes.add("unique")
         # fields involved in a unique together constraint have an implied
         # "required" state, so we're adding the "required" error code to them
         implicitly_required_fields = set()
@@ -501,3 +509,9 @@ def get_example_from_exception(exc: exceptions.APIException) -> OpenApiExample:
         response_only=True,
         status_codes=[str(exc.status_code)],
     )
+
+
+def _drf_version():
+    # we just care about major and minor drf versions
+    parts = rest_framework.VERSION.split(".")
+    return int(parts[0]), int(parts[1])

tests/test_openapi_utils.py

@@ -16,6 +16,7 @@
 
 from drf_standardized_errors.openapi_utils import (
     InputDataField,
+    _drf_version,
     get_django_filter_backends,
     get_error_serializer,
     get_filter_forms,
@@ -372,6 +373,43 @@ def test_unique_together_error_codes(unique_together):
     assert "required" in model.error_codes
 
 
+@pytest.fixture
+def unique_together_with_violation_code():
+    from django.db import models
+
+    class SomeModel(models.Model):
+        app_label = models.CharField(max_length=100)
+        model = models.CharField(max_length=100)
+
+        class Meta:
+            constraints = [
+                models.UniqueConstraint(
+                    fields=["app_label", "model"],
+                    name="unique_model",
+                    violation_error_code="custom_violation_code",
+                )
+            ]
+
+    class SomeSerializer(serializers.ModelSerializer):
+        class Meta:
+            model = SomeModel
+            fields = ["app_label", "model"]
+
+    return get_flat_serializer_fields(SomeSerializer())
+
+
+@pytest.mark.skipif(
+    _drf_version() < (3, 17) or django.VERSION < (5, 0),
+    reason="django added violation_error_code in v5 and drf supported it in v3.17",
+)
+def test_unique_together_new(unique_together_with_violation_code):
+    non_field_errors, _, __ = get_serializer_fields_with_error_codes(
+        unique_together_with_violation_code
+    )
+
+    assert "custom_violation_code" in non_field_errors.error_codes
+
+
 class PostSerializer(serializers.ModelSerializer):
     """
     Intentional required=False to test that the 'required' error code is added