Describe the problem you are trying to fix (provide as much context as possible)

Currently it is not possible to create a schema with nested objects where xor and nand checks are applied among the others with peers as input parameter. Please see the following schema as an example:

Joi.object().keys({
  a: {
    x: Joi.number(),
  },
  b: {
    y: Joi.string(),
    z: Joi.string(),
  }
})

The problem is that the checks which use peers only applies to siblings and not the sublings' childrens. For example, say we want to perform an xor check on x and z then we cannot use object.xor() as its parameter does not accept a reference such as a.x and b.z.

Which API (or modification of the current API) do you suggest to solve that problem ?

I suggest using references where peers are used today for the following functions

• object.and(peers)
• object.nand(peers)
• object.or(peers)
• object.xor(peers)
• object.with(key, peers)
• object.without(key, peers)

That way, the schema could be created like this with the addition of .xor('a.x', 'b.z') in the end

Joi.object().keys({
  a: {
    x: Joi.number(),
  },
  b: {
    y: Joi.string(),
    z: Joi.string(),
  }
}).xor('a.x', 'b.z')

Are you ready to work on a pull request if your suggestion is accepted ?

Unfortunately not.