Fix InitSource bug in case of nested model using alias (#240)

Author: hramezani

pydantic_settings/sources.py

@@ -165,7 +165,7 @@ def get_field_value(self, field: FieldInfo, field_name: str) -> tuple[Any, str,
         return None, '', False
 
     def __call__(self) -> dict[str, Any]:
-        return TypeAdapter(Dict[str, Any]).dump_python(self.init_kwargs)
+        return TypeAdapter(Dict[str, Any]).dump_python(self.init_kwargs, by_alias=True)
 
     def __repr__(self) -> str:
         return f'InitSettingsSource(init_kwargs={self.init_kwargs!r})'

tests/test_settings.py

@@ -2367,3 +2367,14 @@ class Settings(BaseSettings):
 
     s = Settings()
     assert s.model_dump() == {'foo': '1', 'extra_var': 'extra_value'}
+
+
+def test_nested_field_with_alias_init_source():
+    class NestedSettings(BaseModel):
+        foo: str = Field(alias='fooAlias')
+
+    class Settings(BaseSettings):
+        nested_foo: NestedSettings
+
+    s = Settings(nested_foo=NestedSettings(fooAlias='EXAMPLE'))
+    assert s.model_dump() == {'nested_foo': {'foo': 'EXAMPLE'}}