Combining DisplayFromStr and Uppercase

[ctron]

I am trying to de-serialize into a type using from_str, however I would like the string to upper all upper cases before handing over the data to from_str.

I noticed there is a "format" Uppercase, but I couldn't find any example on how to use it.

[jonasbb]

Hi, that is currently not possible. The DisplayFromStr does not allow any modification of the serialized string. I don't think it necessarily makes sense to add support for that in this crate. It is simple enough to create your own custom MyDisplayFromStr type with any string modification operation you need, instead of a limited pre-defined set. You could also define a generic type like MyDisplayFromStr<Uppercase> if you need that flexibility. Uppercasing a String is also so complicated that it has different meanings, so picking one probably doesn't work too well.

Uppercase cannot be combined with any arbitrary other type. The types in the format module are only needed if some other type needs them. For example, you can specify the formatting of your hex values https://docs.rs/serde_with/latest/serde_with/hex/struct.Hex.html. Hex doesn't have the same String uppercasing problems, since we have a limited characterset here.