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Context

• node version: v13.6.0
• module version: 17.1.1
• environment (e.g. node, browser, native): node
• used with (e.g. hapi application, another framework, standalone, ...): standalone
• any other relevant information: N/A

How can we help?

I was searching to make actual validation logic along with data format or type check.
for example: define and check if a record with id (given in the input params) exists.
I've tried external but the problem is value is not replaced so I have to fetch the object again after the validation

async function method(id) {
  const user = await User.findById(id)
  if !_.isNil(user) {
    return new Error("user is not found");
  } else {
    return user
  }
}

const schema = Joi.object({
  name: Joi.string().required(),
  id: Joi.number().external(method, "custom validation")
})

so I am asking if that's supported

an example from ruby code

 params do
    required(:room_id).value(:integer)
    required(:user_id).value(:integer)
    required(:start_date).value(:time)
    required(:end_date).value(:time)
    optional(:notes).value(:string)
  end

  rule(:room_id) do
    room = Room.find_by(id: value)

    if room.present?
      values[:room] = room
    else
      key.failure('could not be found')
    end
  end