Model string value from external system

Alternatively, you can use rescript-schema to leverage data transformation when interacting with external systems:

type info = {
  contractPerson: option<string>,
}

let infoSchema = S.object(s => {
  contractPerson: s.field("contract_person", S.null(S.string))
})

let data = {
  contractPerson: None,
}->S.serializeOrRaiseWith(infoSchema)

Console.log(data) // { contract_person: null }

Besides the option → null automatic conversion, you can notice in the example that you can also transform field names. And there are many more features you can find in the docs.

Also, there’s a ppx mode:

@schema
type info = {
  @as("contract_person")
  contractPerson: @s.null option<string>,
}

let data = {
  contractPerson: None,
}->S.serializeOrRaiseWith(infoSchema)

Console.log(data) // { contract_person: null }