Allow serDes for types other than string

[rattrayalex]

Is your feature request related to a problem? Please describe.

Right now, serDes only works for fields that are type: 'string', but I have found a few cases where I would like to perform some serialization or deserialization on types other than strings.

One example is turning Date to number; I want type: 'number' in the spec (the API has seconds since epoch), but on the backend I want Date types.

  {
    format: "my-timestamp",
    deserialize: (seconds: number): Date => new Date(seconds * 1000),
    serialize: (date: Date): number => (date as Date).getTime(),
  },

However, this doesn't seem to work – serDes only works when type: 'string', even though you can declare custom formats for type: 'number'.

Another example is booleans in query strings; I would like to be able to transform all type: 'boolean' objects into an actual boolean when they appear as strings, like so:

{
  type: 'boolean',
  format: 'querystring-boolean'
  deserialize: (bool: boolean | 'true' | 'false'): boolean => (bool === true || bool === 'true'),
  serialize: (bool: boolean): boolean => bool,
}

Describe the solution you'd like
I would like serDes to allow any field with a format to be serialized and deserialized with a custom function, not just strings.

Describe alternatives you've considered
The only workarounds I can think of right now is to use type: 'string' everywhere, or to manually convert them in all my function calls, neither of which is palatable.

[rattrayalex]

Updated the description and title with more generic (and I hope compelling) examples.

[rattrayalex]

Note that currently, the output of any custom deserialize function seems to stringified after the fact, so you can't hack around this right now.

[pilerou]

Hello @rattrayalex

I'm looking at this enhancement.
Should we make a very generic mecanism or is there other literal types ?
I think we can deal with number, boolean and string but I can't see more.

For example, I don't think BigInt is universal enough.

Am I right ?
If it is OK to you, I can try to make the changes

[rattrayalex]

Hi @pilerou,

Thanks for looking into this!

My hunch is that it should be fully generic. For example, there may even be a type: object that gets serialized into a class instantiation or something.

I'm not quite sure what you mean about BigInt but I could also imagine someone using a custom datatype for those too (like a big decimal datatype for example).

I hope this helps?