Question

My application contain big form with 18 fields. It is processed with standard form mapping, like this:

val bigForm = Form(
  mapping(
    "id"    -> of[ObjectId],
    "title" -> text,
    // And another 16 fields...
    ...
  )
)

And all was well, but today I decided to add one more field and here comes the problem – mapping is not able to take more than 18 arguments.

What should I do then? I thinking of combining some fields into the structure, but additional structure requires additional formatter, JSON serializer and deserializer, too much work. I’m looking for a general solution, more fields are likely to appear in the future.

Another solution I’m thinking about is to handle form manually, without Form‘s.

Are there better solutions?

Answer 1

You can use nested mappings, e.g.

val bigForm = Form(
  mapping(
    "id"    -> of[ObjectId],
    "title" -> text,
    "general" -> mapping(
      ...
    )(GeneralInfo.apply)(GeneralInfo.unapply),
    "advanced" -> mapping(
      ...
    )(AdvancedInfo.apply)(AdvancedInfo.unapply)
  )
)