From 9c38ec39cd349a96c0544a4005bdd338c3b07274 Mon Sep 17 00:00:00 2001
From: Sidney Richards <sidney@maykinmedia.nl>
Date: Thu, 12 Dec 2024 16:08:02 +0100
Subject: [PATCH] Add slug field validation

---
 django_setup_configuration/fields.py |  6 +++-
 testapp/models.py                    |  1 +
 tests/test_django_model_ref_field.py | 54 ++++++++++++++++++++++++++++
 3 files changed, 60 insertions(+), 1 deletion(-)

diff --git a/django_setup_configuration/fields.py b/django_setup_configuration/fields.py
index 4c40a52..15dc50b 100644
--- a/django_setup_configuration/fields.py
+++ b/django_setup_configuration/fields.py
@@ -7,6 +7,7 @@
 from django.db import models
 from django.db.models.fields import NOT_PROVIDED, Field
 
+from pydantic import constr
 from pydantic.fields import FieldInfo
 
 
@@ -47,6 +48,9 @@ class UNMAPPED_DJANGO_FIELD:
     pass
 
 
+_SLUG_RE = r"^[-a-zA-Z0-9_]+\z"
+
+
 class DjangoModelRefInfo(FieldInfo):
     """
     A FieldInfo representing a reference to a field on a Django model.
@@ -142,8 +146,8 @@ def _get_python_type(
             models.TextField: str,
             models.EmailField: str,
             models.URLField: str,
-            models.SlugField: str,
             models.UUIDField: str,
+            models.SlugField: constr(pattern=_SLUG_RE),
             # Integer-based fields
             models.AutoField: int,
             models.SmallAutoField: int,
diff --git a/testapp/models.py b/testapp/models.py
index dcecc3f..d0eb7cf 100644
--- a/testapp/models.py
+++ b/testapp/models.py
@@ -14,6 +14,7 @@ class TestModel(models.Model):
     nullable_str = models.CharField(null=True, blank=False, max_length=1)
     nullable_and_blank_str = models.CharField(null=True, blank=False, max_length=1)
     blank_str = models.CharField(null=False, blank=True, max_length=1)
+    slug = models.SlugField()
 
     field_with_help_text = models.IntegerField(help_text="This is the help text")
     field_with_verbose_name = models.IntegerField(verbose_name="The Verbose Name")
diff --git a/tests/test_django_model_ref_field.py b/tests/test_django_model_ref_field.py
index c64af66..322dc47 100644
--- a/tests/test_django_model_ref_field.py
+++ b/tests/test_django_model_ref_field.py
@@ -1,6 +1,10 @@
 from typing import Literal
 
+from django.core.exceptions import ValidationError as DjangoValidationError
+from django.core.validators import validate_slug
+
 import pytest
+from pydantic import ValidationError
 from pydantic.fields import PydanticUndefined
 
 from django_setup_configuration.fields import DjangoModelRef
@@ -51,6 +55,56 @@ class Config(ConfigurationModel):
     assert field.is_required() is True
 
 
+@pytest.mark.parametrize(
+    "invalid_values",
+    (
+        "",
+        "hello world",
+        "user@email.com",
+        "$price",
+        "my.variable",
+        "résumé",
+        "hello!",
+        "!",
+        "#",
+        "+",
+    ),
+)
+def test_slug_validation_fails_on_both_pydantic_and_django(invalid_values):
+
+    class Config(ConfigurationModel):
+        slug = DjangoModelRef(TestModel, "slug")
+
+    with pytest.raises(ValidationError):
+        Config(slug=invalid_values)
+
+    with pytest.raises(DjangoValidationError):
+        validate_slug(invalid_values)
+
+
+@pytest.mark.parametrize(
+    "valid_values",
+    (
+        "a",
+        "foo-bar",
+        "foo_bar",
+        "foo_bar_baz",
+        "foo-bar-baz",
+        "fO0-B4r-Baz",
+        "foo-bar-baz",
+        "foobarbaz",
+        "FooBarBaz",
+    ),
+)
+def test_slug_validation_succeeds_on_both_pydantic_and_django(valid_values):
+
+    class Config(ConfigurationModel):
+        slug = DjangoModelRef(TestModel, "slug")
+
+    Config.model_validate(dict(slug=valid_values))
+    validate_slug(valid_values)  # does not raise
+
+
 def test_no_default_makes_field_required():
 
     class Config(ConfigurationModel):