From 853b8c9c50c0bff587f10865a2e9e5cbd0c0f36c Mon Sep 17 00:00:00 2001 From: Yurii Motov Date: Mon, 17 Nov 2025 22:48:59 +0100 Subject: [PATCH] Assign `alias` to `validation_alias` and `serialization_alias` in `Body` and `Param` This is how it's done in Pydantic's Field: https://github.com/pydantic/pydantic/blob/407934af10962473d8db0b8c693393cad3975eda/pydantic/fields.py#L1346-L1350 --- fastapi/params.py | 8 ++++++++ 1 file changed, 8 insertions(+) diff --git a/fastapi/params.py b/fastapi/params.py index 6a58d5808..fd9380776 100644 --- a/fastapi/params.py +++ b/fastapi/params.py @@ -115,6 +115,10 @@ class Param(FieldInfo): # type: ignore[misc] else: kwargs["deprecated"] = deprecated if PYDANTIC_V2: + if serialization_alias in (_Unset, None) and isinstance(alias, str): + serialization_alias = alias + if validation_alias in (_Unset, None): + validation_alias = alias kwargs.update( { "annotation": annotation, @@ -571,6 +575,10 @@ class Body(FieldInfo): # type: ignore[misc] else: kwargs["deprecated"] = deprecated if PYDANTIC_V2: + if serialization_alias in (_Unset, None) and isinstance(alias, str): + serialization_alias = alias + if validation_alias in (_Unset, None): + validation_alias = alias kwargs.update( { "annotation": annotation,