Fix nested model field with alias parsing (#400)

pydantic_settings/sources.py

@@ -824,13 +824,14 @@ class Cfg(BaseSettings):
  fields = _get_model_fields(annotation)
  # `case_sensitive is None` is here to be compatible with the old behavior.
  # Has to be removed in V3.
- if (case_sensitive is None or case_sensitive) and fields.get(key):
- return fields[key]
- elif not case_sensitive:
- for field_name, f in fields.items():
- if field_name.lower() == key.lower():
+ for field_name, f in fields.items():
+ if case_sensitive is None or case_sensitive:
+ if (field_name == key) or (isinstance(f.validation_alias, str) and f.validation_alias == key):
  return f
-
+ elif (field_name.lower() == key.lower()) or (
+ isinstance(f.validation_alias, str) and f.validation_alias.lower() == key.lower()
+ ):
+ return f
  return None
 
  def explode_env_vars(self, field_name: str, field: FieldInfo, env_vars: Mapping[str, str | None]) -> dict[str, Any]:

tests/test_settings.py

@@ -5004,3 +5004,45 @@ class Settings(BaseSettings):
  foo: list[str] = []
 
  Settings()
+
+
+def test_nested_model_field_with_alias(env):
+ class NestedSettings(BaseModel):
+ foo: List[str] = Field(alias='fooalias')
+
+ class Settings(BaseSettings):
+ model_config = SettingsConfigDict(env_nested_delimiter='__')
+
+ nested: NestedSettings
+
+ env.set('nested__fooalias', '["one", "two"]')
+
+ s = Settings()
+ assert s.model_dump() == {'nested': {'foo': ['one', 'two']}}
+
+
+def test_nested_model_field_with_alias_case_sensitive(monkeypatch):
+ class NestedSettings(BaseModel):
+ foo: List[str] = Field(alias='fooAlias')
+
+ class Settings(BaseSettings):
+ model_config = SettingsConfigDict(env_nested_delimiter='__', case_sensitive=True)
+
+ nested: NestedSettings
+
+ # Need to patch os.environ to get build to work on Windows, where os.environ is case insensitive
+ monkeypatch.setattr(os, 'environ', value={'nested__fooalias': '["one", "two"]'})
+ with pytest.raises(ValidationError) as exc_info:
+ Settings()
+ assert exc_info.value.errors(include_url=False) == [
+ {
+ 'type': 'missing',
+ 'loc': ('nested', 'fooAlias'),
+ 'msg': 'Field required',
+ 'input': {'fooalias': '["one", "two"]'},
+ }
+ ]
+
+ monkeypatch.setattr(os, 'environ', value={'nested__fooAlias': '["one", "two"]'})
+ s = Settings()
+ assert s.model_dump() == {'nested': {'foo': ['one', 'two']}}