How can I use Joi to validate an object with unknown keys and check that the values are scalar types?

Question

I have an object whose keys I cannot determine ahead of time. How can I enforce specific types (scalar types) for the values using Joi?

Example object with unknown keys:

const obj = {
  x: "foo",
  y: 7,
  z: true,
  p: { m: 1, n: false },
  q: [ "a", "b", "c" ]
}

Since I only want to accept scalar types, it means that keys p and q should cause a validation failure.

How can I achieve this with Joi?

So far I have tried this but it allows non-scalar values like ['a', 'b', 'c'] :

Joi.object().pattern(Joi.string(), Joi.boolean(), Joi.number())

Answer 1

Got it working with this

const validationSchema = Joi.object().pattern(
  Joi.string(),
  Joi.alternatives().try(Joi.number(), Joi.string(), Joi.boolean())
);

See sandbox