add support for django.conf.settings.SETTING_NAME

mypy_django_plugin/helpers.py

@@ -1,8 +1,10 @@
-from typing import Dict, Optional, Type, Tuple, NamedTuple
+from typing import Dict, Optional, NamedTuple
 
-from mypy.nodes import SymbolTableNode, Var, Expression, MemberExpr
+from mypy.semanal import SemanticAnalyzerPass2
+from mypy.types import Type
+from mypy.nodes import SymbolTableNode, Var, Expression
 from mypy.plugin import FunctionContext
-from mypy.types import Instance
+from mypy.types import Instance, UnionType, NoneTyp
 
 MODEL_CLASS_FULLNAME = 'django.db.models.base.Model'
 QUERYSET_CLASS_FULLNAME = 'django.db.models.query.QuerySet'
@@ -13,7 +15,6 @@ ONETOONE_FIELD_FULLNAME = 'django.db.models.fields.related.OneToOneField'
 def create_new_symtable_node(name: str, kind: int, instance: Instance) -> SymbolTableNode:
     new_var = Var(name, instance)
     new_var.info = instance.type
-
     return SymbolTableNode(kind, new_var,
                            plugin_generated=True)
 
@@ -53,3 +54,14 @@ def get_call_signature_or_none(ctx: FunctionContext) -> Optional[Dict[str, Argum
         result[arg_name] = (arg[0], arg_type[0])
 
     return result
+
+
+def make_optional(typ: Type) -> Type:
+    return UnionType.make_simplified_union([typ, NoneTyp()])
+
+
+def make_required(typ: Type) -> Type:
+    if not isinstance(typ, UnionType):
+        return typ
+    items = [item for item in typ.items if not isinstance(item, NoneTyp)]
+    return UnionType.make_union(items)

mypy_django_plugin/main.py

@@ -1,5 +1,8 @@
+import os
 from typing import Callable, Optional
 
+from django.conf import Settings
+from mypy.options import Options
 from mypy.plugin import Plugin, FunctionContext, ClassDefContext
 from mypy.types import Type
 
@@ -8,6 +11,7 @@ from mypy_django_plugin.plugins.objects_queryset import set_objects_queryset_to_
 from mypy_django_plugin.plugins.postgres_fields import determine_type_of_array_field
 from mypy_django_plugin.plugins.related_fields import set_related_name_instance_for_onetoonefield, \
     set_related_name_manager_for_foreign_key, set_fieldname_attrs_for_related_fields
+from mypy_django_plugin.plugins.setup_settings import DjangoConfSettingsInitializerHook
 
 
 base_model_classes = {helpers.MODEL_CLASS_FULLNAME}
@@ -21,6 +25,15 @@ def transform_model_class(ctx: ClassDefContext) -> None:
 
 
 class DjangoPlugin(Plugin):
+    def __init__(self,
+                 options: Options) -> None:
+        super().__init__(options)
+        self.django_settings = None
+
+        django_settings_module = os.environ.get('DJANGO_SETTINGS_MODULE')
+        if django_settings_module:
+            self.django_settings = Settings(django_settings_module)
+
     def get_function_hook(self, fullname: str
                           ) -> Optional[Callable[[FunctionContext], Type]]:
         if fullname == helpers.FOREIGN_KEY_FULLNAME:
@@ -37,6 +50,8 @@ class DjangoPlugin(Plugin):
                             ) -> Optional[Callable[[ClassDefContext], None]]:
         if fullname in base_model_classes:
             return transform_model_class
+        if fullname == 'django.conf._DjangoConfLazyObject':
+            return DjangoConfSettingsInitializerHook(settings=self.django_settings)
         return None
 
 

mypy_django_plugin/plugins/setup_settings.py

@@ -0,0 +1,34 @@
+from typing import cast, Any
+
+from django.conf import Settings
+from mypy.nodes import MDEF, TypeInfo, SymbolTable
+from mypy.plugin import ClassDefContext
+from mypy.semanal import SemanticAnalyzerPass2
+from mypy.types import Instance, AnyType, TypeOfAny
+
+from mypy_django_plugin import helpers
+
+
+def get_obj_type_name(value: Any) -> str:
+    return type(value).__module__ + '.' + type(value).__qualname__
+
+
+class DjangoConfSettingsInitializerHook(object):
+    def __init__(self, settings: Settings):
+        self.settings = settings
+
+    def __call__(self, ctx: ClassDefContext) -> None:
+        api = cast(SemanticAnalyzerPass2, ctx.api)
+        for name, value in self.settings.__dict__.items():
+            if name.isupper():
+                if value is None:
+                    ctx.cls.info.names[name] = helpers.create_new_symtable_node(name, MDEF,
+                                                                                instance=api.builtin_type('builtins.object'))
+                    continue
+
+                type_fullname = get_obj_type_name(value)
+                sym = api.lookup_fully_qualified_or_none(type_fullname)
+                if sym is not None:
+                    args = len(sym.node.type_vars) * [AnyType(TypeOfAny.from_omitted_generics)]
+                    ctx.cls.info.names[name] = helpers.create_new_symtable_node(name, MDEF,
+                                                                                instance=Instance(sym.node, args))