v2.1.1

CHANGELOG.md

@@ -1,5 +1,12 @@
 # Change Log
 
+## [2.1.1] - 2025-10-12
+
+Changes:
+
+- Fixed a bug where custom extra handler strings in settings could not be properly resolved, imported, or called.
+- Dev: Update the dependencies
+
 ## [2.1.0] - 2025-08-17
 
 Changes:

drf_simple_api_errors/__init__.py

@@ -1,4 +1,4 @@
 from .exception_handler import exception_handler
 
 __all__ = ("exception_handler",)
-__version__ = "2.1.0"
+__version__ = "2.1.1"

drf_simple_api_errors/extra_handlers.py

@@ -13,9 +13,7 @@
 from rest_framework import exceptions
 
 
-def set_default_detail_to_formatted_exc_default_code(
-    exc: exceptions.APIException,
-) -> exceptions.APIException:
+def set_default_detail_to_formatted_exc_default_code(exc: Exception) -> Exception:
     """
     Formats the `default_detail` for specific DRF exceptions
     by setting it to a human-readable string based on the exception `default_code`.

drf_simple_api_errors/handlers.py

@@ -10,7 +10,8 @@
     - `get_response_headers`: Gets the response headers for the given exception.
 """
 
-from typing import Dict, Union
+import importlib
+from typing import Callable, Dict, Union
 
 from django.core.exceptions import (
     PermissionDenied,
@@ -23,27 +24,57 @@
 from drf_simple_api_errors import extra_handlers
 from drf_simple_api_errors.settings import api_settings
 
+DEFAULT_EXTRA_HANDLERS = [
+    extra_handlers.set_default_detail_to_formatted_exc_default_code
+]
+"""Default extra handlers to always apply."""
+
 
 def apply_extra_handlers(exc: Exception):
     """
     Apply any extra exception handlers defined in the settings.
 
     Args:
         exc (Exception): The exception to handle.
+
+    Returns:
+        int: The number of handlers applied (this is mainly for unit testing).
     """
     # Get the default extra handlers and the ones defined in the settings.
     # The default handlers are always applied to ensure that exceptions
     # are formatted correctly.
-    default_extra_handlers = [
-        extra_handlers.set_default_detail_to_formatted_exc_default_code
-    ]
-    settings_extra_handlers = api_settings.EXTRA_HANDLERS
-
-    extra_handlers_to_apply = default_extra_handlers + settings_extra_handlers
+    # Resolve the settings extra handlers.
+    # The settings extra handlers is a list of strings representing
+    # the import path to the handler function.
+    # This allows for lazy loading of the handlers.
+    settings_extra_handlers: list[Callable] = []
+    for handler_path in api_settings.EXTRA_HANDLERS or []:
+        if not isinstance(handler_path, str):
+            raise ValueError(
+                f"EXTRA_HANDLERS must be a list of strings. Found: {type(handler_path)}"
+            )
+
+        module_path, func_name = handler_path.rsplit(".", 1)
+        try:
+            module = importlib.import_module(module_path)
+        except ModuleNotFoundError:
+            raise ValueError(f"Path {handler_path} not found.")
+
+        func = getattr(module, func_name, None)
+        if func is None:
+            raise ValueError(f"Handler {func_name} not found.")
+        if not callable(func):
+            raise ValueError(f"Handler {func_name} is not callable.")
+        else:
+            settings_extra_handlers.append(func)
+
+    extra_handlers_to_apply = DEFAULT_EXTRA_HANDLERS + settings_extra_handlers
     if extra_handlers_to_apply:
         for handler in extra_handlers_to_apply:
             handler(exc)
 
+    return len(extra_handlers_to_apply)
+
 
 def convert_django_exc_to_drf_api_exc(
     exc: Exception,

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "drf-simple-api-errors"
-version = "2.1.0"
+version = "2.1.1"
 description = "A library for Django Rest Framework returning consistent and easy-to-parse API error messages."
 authors = ["Gian <[email protected]>"]
 license = "MIT"
@@ -33,6 +33,7 @@ classifiers = [
     "Topic :: Software Development :: Libraries :: Python Modules",
 ]
 include = ["drf_simple_api_errors", "LICENSE.md"]
+requires-poetry = "^2.1"
 
 
 [tool.poetry.dependencies]
@@ -46,6 +47,7 @@ djangorestframework = ">=3.0"
 black = "^24.1.1"
 factory-boy = "^3.3.0"
 flake8 = "^7.0.0"
+ipdb = "^0.13.13"
 isort = "^5.13.2"
 pytest = "^8.0.0"
 pytest-cov = "^5.0.0"
@@ -82,5 +84,5 @@ pythonpath = [".", "integration_tests", "tests"]
 
 
 [build-system]
-requires = ["poetry-core"]
+requires = ["poetry-core>=2.0.0,<3.0.0"]
 build-backend = "poetry.core.masonry.api"

tests/test_hadlers.py

@@ -1,3 +1,6 @@
+import importlib
+import types
+
 from django.core import exceptions as django_exceptions
 from django.http import Http404
 from rest_framework import exceptions as drf_exceptions
@@ -10,35 +13,143 @@
 class TestApplyExtraHandlers:
     """Test cases for the apply_extra_handlers function in handlers module."""
 
-    def test_extra_handlers_called(self, mocker):
+    @pytest.fixture
+    def mock_importlib_import_module(self, mocker):
+        """Mock importlib.import_module to control the import behavior in tests."""
+        return mocker.patch.object(importlib, "import_module")
+
+    def test_calls_expected_default_handlers(self, mocker):
+        """Test that all the expected default handlers are called.
+
+        This is a sanity check to ensure that the default handlers are always called.
+        """
+        # Always make sure that the settings handlers are empty for this test
+        # to isolate the default handlers.
+        mocker.patch("drf_simple_api_errors.settings.api_settings.EXTRA_HANDLERS", [])
+
+        extra_handlers_applied = handlers.apply_extra_handlers(Exception())
+
+        assert extra_handlers_applied == len(handlers.DEFAULT_EXTRA_HANDLERS)
+
+    def test_extra_handlers_calls_string_import(
+        self, monkeypatch, mocker, mock_importlib_import_module
+    ):
+        """Test that extra handlers with string imports are called correctly."""
+        # Set default handlers to empty for this test to isolate the settings one.
+        monkeypatch.setattr(handlers, "DEFAULT_EXTRA_HANDLERS", [])
+        # Make importlib.import_module return the test mock handler when called
+        mock_handler = mocker.MagicMock()
+        dummy_module = types.SimpleNamespace(mock_handler=mock_handler)
+        mock_importlib_import_module.return_value = dummy_module
+        # Patch the settings to include the test mock handler
+        monkeypatch.setattr(
+            "drf_simple_api_errors.settings.api_settings.EXTRA_HANDLERS",
+            # Add dummy path to have at least one mock handler to import from a string
+            ["path.to.module.mock_handler"],
+        )
+
+        # exc = mocker.MagicMock()
+        exc = Exception()
+        extra_handlers_applied = handlers.apply_extra_handlers(exc)
+
+        assert extra_handlers_applied == 1
+        mock_handler.assert_called_once_with(exc)
+
+    def test_extra_handlers_calls_multiple(
+        self, monkeypatch, mocker, mock_importlib_import_module
+    ):
+        """
+        Test that both default and settings extra handlers are called correctly.
+        """
+        # Make importlib.import_module return the test mock handler when called
+        mock_handler = mocker.MagicMock()
+        dummy_module = types.SimpleNamespace(mock_handler=mock_handler)
+        mock_importlib_import_module.return_value = dummy_module
+        # Patch the settings to include the test mock handler
+        monkeypatch.setattr(
+            "drf_simple_api_errors.settings.api_settings.EXTRA_HANDLERS",
+            # Add dummy path to have at least one mock handler to import from a string
+            ["path.to.module.mock_handler"],
+        )
+
+        # exc = mocker.MagicMock()
+        exc = Exception()
+        extra_handlers_applied = handlers.apply_extra_handlers(exc)
+
+        assert (
+            extra_handlers_applied == len(handlers.DEFAULT_EXTRA_HANDLERS) + 1
+        )  # 1 for the settings handler
+        mock_handler.assert_called_once_with(exc)
+
+    def test_extra_handlers_value_error_on_non_string_import(self, monkeypatch, mocker):
         """
-        Test that extra handlers are called with the exception.
+        Test that a ValueError is raised when EXTRA_HANDLERS contains
+        a non-string import.
+        """
+        monkeypatch.setattr(
+            "drf_simple_api_errors.settings.api_settings.EXTRA_HANDLERS",
+            [mocker.MagicMock()],
+        )
+
+        with pytest.raises(ValueError) as e:
+            handlers.apply_extra_handlers(Exception())
 
-        Testing with multiple handlers to ensure all are invoked, and this gives
-        confidence one or more than two handlers can be used correctly.
+        assert "EXTRA_HANDLERS must be a list of strings" in str(e.value)
+
+    def test_extra_handlers_value_error_when_path_to_extra_handler_not_found(
+        self, monkeypatch, mocker
+    ):
+        """
+        Test that a ValueError is raised when the path to the extra handler
+        does not exist.
         """
-        mock_extra_handler = mocker.MagicMock()
-        mock_another_extra_handler = mocker.MagicMock()
+        monkeypatch.setattr(
+            "drf_simple_api_errors.settings.api_settings.EXTRA_HANDLERS",
+            ["path.to.non_existent_handler"],
+        )
 
-        mocker.patch(
+        with pytest.raises(ValueError) as e:
+            handlers.apply_extra_handlers(Exception())
+
+        assert "Path path.to.non_existent_handler not found." in str(e.value)
+
+    def test_extra_handlers_value_error_when_extra_handler_is_none(
+        self, monkeypatch, mocker, mock_importlib_import_module
+    ):
+        """
+        Test that a ValueError is raised when the extra handler is None.
+        """
+        # Make importlib.import_module return a module without the expected attribute
+        dummy_module = types.SimpleNamespace()
+        mock_importlib_import_module.return_value = dummy_module
+        monkeypatch.setattr(
             "drf_simple_api_errors.settings.api_settings.EXTRA_HANDLERS",
-            [mock_extra_handler, mock_another_extra_handler],
+            ["path.to.module.non_existent_handler"],
         )
 
-        exc = mocker.MagicMock()
-        handlers.apply_extra_handlers(exc)
+        with pytest.raises(ValueError) as e:
+            handlers.apply_extra_handlers(Exception())
 
-        mock_extra_handler.assert_called_once_with(exc)
-        mock_another_extra_handler.assert_called_once_with(exc)
+        assert "Handler non_existent_handler not found." in str(e.value)
 
-    def test_no_extra_handlers(self, mocker):
-        """Test that no extra handlers are called when EXTRA_HANDLERS is empty."""
-        mock_extra_handler = mocker.MagicMock()
+    def test_extra_handlers_value_error_when_extra_handler_not_callable(
+        self, monkeypatch, mocker, mock_importlib_import_module
+    ):
+        """
+        Test that a ValueError is raised when the extra handler is not callable.
+        """
+        # Make importlib.import_module return a non-callable attribute
+        dummy_module = types.SimpleNamespace(mock_handler="not_a_function")
+        mock_importlib_import_module.return_value = dummy_module
+        monkeypatch.setattr(
+            "drf_simple_api_errors.settings.api_settings.EXTRA_HANDLERS",
+            ["path.to.module.mock_handler"],
+        )
 
-        exc = mocker.MagicMock()
-        handlers.apply_extra_handlers(exc)
+        with pytest.raises(ValueError) as e:
+            handlers.apply_extra_handlers(Exception())
 
-        mock_extra_handler.assert_not_called()
+        assert "Handler mock_handler is not callable." in str(e.value)
 
 
 class TestConvertDjangoExcToDRFAPIExc: