How to get instance member value from getSymbolsByUDA

[Remi Thebault]

On Saturday, 26 February 2022 at 11:26:54 UTC, max haughton wrote:
> On Saturday, 26 February 2022 at 10:39:18 UTC, Remi Thebault 
> wrote:
>> Hi all,
>>
>> I'm trying to establish a REST API by using the type system 
>> (used in both client and server code).
>>
>> [...]
>
> https://dlang.org/phobos/std_traits.html#getUDAs

How do I use `getUDAs` in this context?
I have `getUDAs!(req, Param).length == 0`. I think it only works 
on the struct attributes, not on the fields attributes.