Fix fetching env values for nested bytes field (#52)

Author: hramezani

pydantic_settings/sources.py

@@ -532,7 +532,7 @@ def _annotation_is_complex(annotation: type[Any] | None) -> bool:
 
 
 def _annotation_is_complex_inner(annotation: type[Any] | None) -> bool:
-    if lenient_issubclass(annotation, str):
+    if lenient_issubclass(annotation, (str, bytes)):
         return False
 
     return lenient_issubclass(annotation, (BaseModel, Mapping, Sequence, tuple, set, frozenset, deque)) or is_dataclass(

tests/test_settings.py

@@ -1582,3 +1582,25 @@ class Settings(BaseSettings):
     s = Settings()
     assert s.A == 'b'
     assert s.sub_MODEL.v == 'v1'
+
+
+def test_nested_bytes_field(env):
+    class SubModel(BaseModel):
+        v1: str
+        v2: bytes
+
+    class Settings(BaseSettings):
+        v0: str
+        sub_model: SubModel
+
+        model_config = ConfigDict(env_nested_delimiter='__', env_prefix='TEST_')
+
+    env.set('TEST_V0', 'v0')
+    env.set('TEST_SUB_MODEL__V1', 'v1')
+    env.set('TEST_SUB_MODEL__V2', 'v2')
+
+    s = Settings()
+
+    assert s.v0 == 'v0'
+    assert s.sub_model.v1 == 'v1'
+    assert s.sub_model.v2 == b'v2'