add config file support

README.md

@@ -24,12 +24,23 @@ plugins =
 in your `mypy.ini` file.
 
 
-### `django.conf.settings` support
+## Configuration
 
-`settings.SETTING_NAME` will only work if `DJANGO_SETTINGS_MODULE` will be present in the environment, when mypy is executed.
+In order to specify config file, set `MYPY_DJANGO_CONFIG` environment variable with path to the config file.
 
-If some setting is not recognized to the plugin, but it's clearly there, try adding type annotation to it.
+Config file format (.ini):
+```
+[mypy_django_plugin]
 
+# specify settings module to use for django.conf.settings, this setting
+# could also be specified with DJANGO_SETTINGS_MODULE environment variable
+# (it also takes priority over config file)
+django_settings = mysettings.local
+
+# if True, all unknown settings in django.conf.settings will fallback to Any,
+# specify it if your settings are loaded dynamically to avoid false positives
+ignore_missing_settings = True
+```
 
 ## To get help
 

mypy_django_plugin/main.py

@@ -1,6 +1,8 @@
 import os
+from configparser import ConfigParser
 from typing import Callable, Dict, Optional, cast
 
+from dataclasses import dataclass
 from mypy.checker import TypeChecker
 from mypy.nodes import TypeInfo
 from mypy.options import Options
@@ -89,6 +91,23 @@ def set_primary_key_marking(ctx: FunctionContext) -> Type:
     return ctx.default_return_type
 
 
+@dataclass
+class Config:
+    django_settings_module: Optional[str] = None
+    ignore_missing_settings: bool = False
+
+    @classmethod
+    def from_config_file(self, fpath: str) -> 'Config':
+        ini_config = ConfigParser()
+        ini_config.read(fpath)
+        if not ini_config.has_section('mypy_django_plugin'):
+            raise ValueError('Invalid config file: no [mypy_django_plugin] section')
+        return Config(django_settings_module=ini_config.get('mypy_django_plugin', 'django_settings',
+                                                            fallback=None),
+                      ignore_missing_settings=ini_config.get('mypy_django_plugin', 'ignore_missing_settings',
+                                                             fallback=False))
+
+
 class DjangoPlugin(Plugin):
     def __init__(self, options: Options) -> None:
         super().__init__(options)
@@ -96,8 +115,18 @@ class DjangoPlugin(Plugin):
         monkeypatch.restore_original_load_graph()
         monkeypatch.restore_original_dependencies_handling()
 
+        config_fpath = os.environ.get('MYPY_DJANGO_CONFIG')
+        if config_fpath:
+            self.config = Config.from_config_file(config_fpath)
+            self.django_settings = self.config.django_settings_module
+        else:
+            self.config = Config()
+            self.django_settings = None
+
+        if 'DJANGO_SETTINGS_MODULE' in os.environ:
+            self.django_settings = os.environ['DJANGO_SETTINGS_MODULE']
+
         settings_modules = ['django.conf.global_settings']
-        self.django_settings = os.environ.get('DJANGO_SETTINGS_MODULE')
         if self.django_settings:
             settings_modules.append(self.django_settings)
 
@@ -163,7 +192,8 @@ class DjangoPlugin(Plugin):
             settings_modules = ['django.conf.global_settings']
             if self.django_settings:
                 settings_modules.append(self.django_settings)
-            return AddSettingValuesToDjangoConfObject(settings_modules)
+            return AddSettingValuesToDjangoConfObject(settings_modules,
+                                                      self.config.ignore_missing_settings)
 
         if fullname in self._get_current_manager_bases():
             return transform_manager_class

mypy_django_plugin/plugins/settings.py

@@ -47,11 +47,15 @@ def load_settings_from_module(settings_classdef: ClassDef, module: MypyFile) ->
 
 
 class AddSettingValuesToDjangoConfObject:
-    def __init__(self, settings_modules: List[str]):
+    def __init__(self, settings_modules: List[str], ignore_missing_settings: bool):
         self.settings_modules = settings_modules
+        self.ignore_missing_settings = ignore_missing_settings
 
     def __call__(self, ctx: ClassDefContext) -> None:
         api = cast(SemanticAnalyzerPass2, ctx.api)
         for module_name in self.settings_modules:
             module = api.modules[module_name]
             load_settings_from_module(ctx.cls, module=module)
+
+        if self.ignore_missing_settings:
+            ctx.cls.info.fallback_to_any = True

test-data/typecheck/config.test

@@ -0,0 +1,23 @@
+[CASE missing_settings_ignored_flag]
+from django.conf import settings
+reveal_type(settings.NO_SUCH_SETTING)  # E: Revealed type is 'Any'
+
+[env MYPY_DJANGO_CONFIG=${MYPY_CWD}/mypy_django.ini]
+
+[file mypy_django.ini]
+[[mypy_django_plugin]
+ignore_missing_settings = True
+[out]
+
+[CASE django_settings_via_config_file]
+from django.conf import settings
+reveal_type(settings.MY_SETTING)  # E: Revealed type is 'builtins.int'
+
+[env MYPY_DJANGO_CONFIG=${MYPY_CWD}/mypy_django.ini]
+[file mypy_django.ini]
+[[mypy_django_plugin]
+django_settings = mysettings
+
+[file mysettings.py]
+MY_SETTING: int = 1
+[out]