Attribute Macro patch 

#[patch]

Declares a PATCH handler inside a #[routes] impl block.

#[patch] records PATCH route metadata and is consumed by #[routes] to build the controller router.

Basic syntax:

#[routes]
impl UsersController {
    #[patch("/:id")]
    async fn update(&self, Path(id): Path<String>, Json(input): Json<UpdateUser>) -> Json<UserDto> {
        Json(self.service.update(id, input).await)
    }
}

Use this macro for partial update endpoints where the handler return type is any Axum-compatible IntoResponse. Common errors are invalid relative paths and forgetting that the controller prefix is prepended by generated router construction.