Add type hints (#21)

* Add type hints

* Redo mypy testing via tox

* Actually use tox in travis build

* Fix tox env usage

* Add Python 3.9 to tox list

* django2.2 -> django2 in tox

* Upgrade pytest-django

* Django 3.x doesn't support Python 3.5

* Deal with FieldDoesNotExist issues

* Explicitly set Python versions

* DRF 3.8/3.9 don't work well with Django 3

* Correct flake8/docs names

* Fix the multiple django specs

* Set deploy job to a TOXENV that still exists

* Fix mypy deps in tox

* Fix lint issues

* Ignore mypy imports for flake8

.travis.yml

@@ -8,6 +8,8 @@ jobs:
     env: TOXENV=py37-flake8
   - python: 3.7
     env: TOXENV=py37-docs
+  - python: 3.7
+    env: TOXENV=py37-mypy
   - python: 3.5
     env: TOXENV=py35-django2-drf3.8
   - python: 3.5

dry_rest_permissions/generics.py

@@ -7,12 +7,26 @@
 they can be consumed by a front end application.
 """
 from functools import wraps
+from typing import Type, cast
+from django.db.models.query import QuerySet
 
 from rest_framework import filters
 from rest_framework import permissions
 from rest_framework import fields
+from rest_framework import request
+from rest_framework import views
+from rest_framework import generics
+
 
 from django.contrib.contenttypes.models import ContentType
+from rest_framework.serializers import ModelSerializer
+
+# gets redefined as true when type checking
+MYPY = False
+
+if MYPY:
+    from django.db import models as django_models  # noqa: F401
+    from typing import List  # noqa: F401
 
 
 class DRYPermissionFiltersBase(filters.BaseFilterBackend):
@@ -34,23 +48,23 @@ class DRYPermissionFiltersBase(filters.BaseFilterBackend):
     """
     action_routing = False
 
-    def filter_queryset(self, request, queryset, view):
+    def filter_queryset(self, request: request.Request, queryset: QuerySet, view: views.APIView):
         """
         This method overrides the standard filter_queryset method.
         This method will check to see if the view calling this is from
         a list type action. This function will also route the filter
         by action type if action_routing is set to True.
         """
         # Check if this is a list type request
-        if view.lookup_field not in view.kwargs:
+        if isinstance(view, generics.GenericAPIView) and view.lookup_field not in view.kwargs:
             if not self.action_routing:
                 return self.filter_list_queryset(request, queryset, view)
             else:
-                method_name = "filter_{action}_queryset".format(action=view.action)
+                method_name = "filter_{action}_queryset".format(action=view.action)  # type: ignore[attr-defined]
                 return getattr(self, method_name)(request, queryset, view)
         return queryset
 
-    def filter_list_queryset(self, request, queryset, view):
+    def filter_list_queryset(self, request: request.Request, queryset: QuerySet, view: views.APIView) -> QuerySet:
         """
         Override this function to add filters.
         This should return a queryset so start with queryset.filter({your filters})
@@ -96,14 +110,16 @@ class DRYPermissions(permissions.BasePermission):
     object_permissions = True
     partial_update_is_update = True
 
-    def has_permission(self, request, view):
+    def has_permission(self, request: request.Request, view: views.APIView):
         """
         Overrides the standard function and figures out methods to call for global permissions.
         """
         if not self.global_permissions:
             return True
 
-        serializer_class = view.get_serializer_class()
+        assert isinstance(view, generics.GenericAPIView), "View needs to descend from GenericAPIView"
+
+        serializer_class = cast(Type[ModelSerializer], view.get_serializer_class())
 
         assert serializer_class.Meta.model is not None, (
             "global_permissions set to true without a model "
@@ -114,7 +130,7 @@ def has_permission(self, request, view):
 
         action_method_name = None
         if hasattr(view, 'action'):
-            action = self._get_action(view.action)
+            action = self._get_action(view.action)  # type: ignore[attr-defined]
             action_method_name = "has_{action}_permission".format(action=action)
             # If the specific action permission exists then use it, otherwise use general.
             if hasattr(model_class, action_method_name):
@@ -123,11 +139,11 @@ def has_permission(self, request, view):
         if request.method in permissions.SAFE_METHODS:
             assert hasattr(model_class, 'has_read_permission'), \
                 self._get_error_message(model_class, 'has_read_permission', action_method_name)
-            return model_class.has_read_permission(request)
+            return model_class.has_read_permission(request)  # type: ignore[attr-defined]
         else:
             assert hasattr(model_class, 'has_write_permission'), \
                 self._get_error_message(model_class, 'has_write_permission', action_method_name)
-            return model_class.has_write_permission(request)
+            return model_class.has_write_permission(request)  # type: ignore[attr-defined]
 
     def has_object_permission(self, request, view, obj):
         """
@@ -299,7 +315,7 @@ class DRYGlobalPermissionsField(fields.Field):
         'write',
         'read'
     ]
-    models = []
+    models = []  # type: List[django_models.Model]
 
     def __init__(self, actions=None, additional_actions=None, **kwargs):
         """See class description for parameters and usage"""

requirements.txt

@@ -14,3 +14,9 @@ wheel==0.24.0
 
 # MkDocs for documentation previews/deploys
 mkdocs==1.2.1
+
+# mypy
+mypy==0.910
+django-stubs==1.8.0
+djangorestframework-stubs==1.4.0
+types-pyyaml==5.4.3

setup.cfg

@@ -1,2 +1,11 @@
 [wheel]
 universal = 1
+
+[mypy]
+show_error_codes = True 
+plugins =
+    mypy_django_plugin.main,
+    mypy_drf_plugin.main
+
+[mypy.plugins.django-stubs]
+django_settings_module = "tests.settings"

setup.py

@@ -39,22 +39,6 @@ def get_packages(package):
             if os.path.exists(os.path.join(dirpath, '__init__.py'))]
 
 
-def get_package_data(package):
-    """
-    Return all files under the root package, that are not in a
-    package themselves.
-    """
-    walk = [(dirpath.replace(package + os.sep, '', 1), filenames)
-            for dirpath, dirnames, filenames in os.walk(package)
-            if not os.path.exists(os.path.join(dirpath, '__init__.py'))]
-
-    filepaths = []
-    for base, filenames in walk:
-        filepaths.extend([os.path.join(base, filename)
-                          for filename in filenames])
-    return {package: filepaths}
-
-
 version = get_version(package)
 
 
@@ -81,7 +65,7 @@ def get_package_data(package):
     author=author,
     author_email=author_email,
     packages=get_packages(package),
-    package_data=get_package_data(package),
+    package_data={"dry_rest_permissions": ["py.typed"]},
     install_requires=[],
     classifiers=[
         'Development Status :: 5 - Production/Stable',

tox.ini

@@ -32,3 +32,11 @@ deps =
 commands = mkdocs build
 deps =
        mkdocs>=0.11.1
+
+[testenv:py37-mypy]
+commands = mypy dry_rest_permissions
+deps =
+       mypy==0.910
+       django-stubs==1.8.0
+       djangorestframework-stubs==1.4.0
+       types-pyyaml==5.4.3