safe check for complex models with env settings

HISTORY.rst

@@ -3,9 +3,10 @@
 History
 -------
 
-v0.6.2 (2017-11-XX)
+v0.6.2 (2017-11-13)
 ...................
 * errors for invalid validator use
+* safer check for complex models in ``Settings``
 
 v0.6.1 (2017-11-08)
 ...................

pydantic/env_settings.py

@@ -9,6 +9,14 @@ class SettingsError(ValueError):
     pass
 
 
+def _complex_field(field):
+    try:
+        return field and (field.shape != Shape.SINGLETON or issubclass(field.type_, (BaseModel, list, set, dict)))
+    except TypeError:
+        # if field.type_ is not a class
+        return False
+
+
 class BaseSettings(BaseModel):
     """
     Base class for settings, allowing values to be overridden by environment variables.
@@ -38,7 +46,7 @@ class BaseSettings(BaseModel):
                 env_name = self.config.env_prefix + field.name.upper()
             env_var = os.getenv(env_name, None)
             if env_var:
-                if field and (field.shape != Shape.SINGLETON or issubclass(field.type_, (BaseModel, list, set, dict))):
+                if _complex_field(field):
                     try:
                         env_var = json.loads(env_var)
                     except ValueError as e:

tests/test_settings.py

@@ -2,7 +2,7 @@ from typing import List, Set
 
 import pytest
 
-from pydantic import BaseModel, BaseSettings, ValidationError
+from pydantic import BaseModel, BaseSettings, NoneStr, ValidationError
 from pydantic.env_settings import SettingsError
 
 
@@ -92,3 +92,12 @@ def test_required_sub_model(env):
     env.set('APP_FOOBAR', '{"pips": "TRUE"}')
     s = Settings()
     assert s.foobar.pips is True
+
+
+def test_non_class(env):
+    class Settings(BaseSettings):
+        foobar: NoneStr
+
+    env.set('APP_FOOBAR', 'xxx')
+    s = Settings()
+    assert s.foobar == 'xxx'