Convert type with option<string> to Js.Nullable.t<string> via PPX

1

Hey everyone!

I am looking to convert a very large type that has ~100 attributes (all mostly strings), its a large type that holds lots of template / page configurations (colors, text, etc) Anyways, we are using this in a NextJs project as well and as some of you probably know, serverside props complains of “undefined” being used over “null”.

Awesome article on this from @ryyppy - ReScript records, NextJS, undefined and getStaticProps - DEV Community

I was wondering if there was a generator (ppx decorator) I could use to simply convert option to Js.Nullable.t

type template = {
  title: string,
  description: option<string>
}

Convert to:

type template = {
  title: string,
  description: Js.Nullable.t<string>
}

Thanks in advance!

1 Like
2

Will you need to both serialize to nulls when sending and deserialize back to undefined on the client?

This is not the answer you were looking for, but there are a couple of functions you may like to consider:

  • Js.Json.serializeExn
  • Js.Json.deserializeUnsafe

I believe these may not be recommended for use, but perhaps it’s fine for simple cases. Maybe some others can explain why.

For a project I’ve worked on I created two similar types (one with option types and one with null types) and functions to transform between the two types, but I didn’t have a large number of fields to deal with so it was not much work, but I’d be interested to hear other suggestions for solution for this.

3

Yea, so for encode/decode JSON we use the @decco ppx.

As for the two types, that is exactly what I did so far to “get it working” - But thought there had to be a better way! :crossed_fingers:t2: