From 1ffbd95579ce4926af095793d4a03c7baf6680a7 Mon Sep 17 00:00:00 2001
From: Oliver Berger <diefans@gmail.com>
Date: Wed, 24 Apr 2024 10:19:30 +0200
Subject: [PATCH] fix: a second level of environment nesting expected a dict
 (#281)

---
 pydantic_settings/sources.py | 3 ++-
 tests/test_settings.py       | 4 ++++
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/pydantic_settings/sources.py b/pydantic_settings/sources.py
index 9c2462ed..eba1fca2 100644
--- a/pydantic_settings/sources.py
+++ b/pydantic_settings/sources.py
@@ -620,7 +620,8 @@ def explode_env_vars(self, field_name: str, field: FieldInfo, env_vars: Mapping[
             target_field: FieldInfo | None = field
             for key in keys:
                 target_field = self.next_field(target_field, key)
-                env_var = env_var.setdefault(key, {})
+                if isinstance(env_var, dict):
+                    env_var = env_var.setdefault(key, {})
 
             # get proper field with last_key
             target_field = self.next_field(target_field, last_key)
diff --git a/tests/test_settings.py b/tests/test_settings.py
index b2663cf0..13598bec 100644
--- a/tests/test_settings.py
+++ b/tests/test_settings.py
@@ -2602,5 +2602,9 @@ class Settings(BaseSettings):
         'nested__foo__bar',
         'this should not be evaluated, since foo is a string by annotation and not a dict',
     )
+    env.set(
+        'nested__foo__bar__baz',
+        'one more',
+    )
     s = Settings()
     assert s.model_dump() == {'nested': {'foo': 'string'}}