Merge pull request #36 from maykinmedia/31-literal-default-values

[#31] Bypass validation of defaults for Django fields containing choices

django_setup_configuration/fields.py

@@ -127,6 +127,17 @@ def __init__(
             else:
                 field_info_creation_kwargs["default"] = inferred_default
 
+        # Defaults for fields with choices often do not map neatly onto the consructed
+        # type used for serialization (e.g. a string) because they may not be a literal
+        # choices but e.g. an enum/Choices member. Inferring the types of the default
+        # can be non-trivial (especially if a default factory is involved), and because
+        # we care about types that can be expressed as simple YAML/JSON scalars, it also
+        # would not make much sense to add complex types to the annotation.
+        validate_defaults = False if self.django_field.choices else True
+        field_info_creation_kwargs["validate_default"] = field_info_creation_kwargs[
+            "validate_return"
+        ] = validate_defaults
+
         return super().__init__(**field_info_creation_kwargs)
 
     @staticmethod
@@ -135,7 +146,10 @@ def _get_python_type(
     ):
         """Map Django field types to Python types."""
         if choices := getattr(django_field, "choices"):
-            choice_values = tuple(choice[0] for choice in choices)
+            choice_values = tuple(
+                choice[0]
+                for choice in (choices if not callable(choices) else choices())
+            )
             return Literal[choice_values]
 
         mapping: Mapping[

testapp/models.py

@@ -25,6 +25,12 @@ class TestModel(models.Model):
     str_with_choices_and_default = models.CharField(
         max_length=3, choices=StrChoices.choices, default=StrChoices.bar
     )
+    str_with_choices_and_incorrectly_typed_default = models.CharField(
+        max_length=3, choices=StrChoices.choices, default=1974
+    )
+    str_with_choices_and_incorrectly_typed_default_factory = models.CharField(
+        max_length=3, choices=StrChoices.choices, default=lambda: 1985
+    )
     str_with_choices_and_blank = models.CharField(
         max_length=3, choices=StrChoices.choices, blank=True
     )
@@ -42,3 +48,7 @@ class TestModel(models.Model):
     int_with_choices_and_blank_and_non_choice_default = models.IntegerField(
         blank=True, choices=((1, "FOO"), (8, "BAR")), default=42
     )
+
+    int_with_choices_callable = models.IntegerField(
+        choices=lambda: ((1, "FOO"), (8, "BAR"))
+    )

tests/test_django_model_ref_field.py

@@ -296,6 +296,22 @@ class Config(ConfigurationModel):
     assert field.is_required() is True
 
 
+def test_int_with_choices_callable_has_literal_annotation():
+
+    class Config(ConfigurationModel):
+        int_with_choices_callable = DjangoModelRef(
+            TestModel, "int_with_choices_callable"
+        )
+
+    field = Config.model_fields["int_with_choices_callable"]
+
+    assert field.title == "int with choices callable"
+    assert field.description is None
+    assert field.annotation == Literal[1, 8]
+    assert field.default == PydanticUndefined
+    assert field.is_required() is True
+
+
 def test_int_with_choices_and_override_has_overridden_annotation():
 
     class Config(ConfigurationModel):
@@ -356,3 +372,18 @@ class Config(ConfigurationModel):
     assert field.annotation == Literal[1, 8] | Literal[42]
     assert field.default == 42
     assert field.is_required() is False
+
+
+def test_choices_with_incorrectly_typed_default_is_not_validated():
+
+    class Config(ConfigurationModel):
+        str_with_choices_and_incorrectly_typed_default = DjangoModelRef(
+            TestModel, "str_with_choices_and_incorrectly_typed_default"
+        )
+        str_with_choices_and_incorrectly_typed_default_factory = DjangoModelRef(
+            TestModel, "str_with_choices_and_incorrectly_typed_default_factory"
+        )
+
+    config = Config()
+    assert config.str_with_choices_and_incorrectly_typed_default == 1974
+    assert config.str_with_choices_and_incorrectly_typed_default_factory == 1985