Nested Joi validations not working using when

Question

I have been trying to get nested where validations, but no luck so far. Here's what I want to achieve:

1- If mainType is COMMERCIAL then define required schema for contactMethod. 2- If isHousing is true then define required schema for contactMethod. 3- If mainType is REAL_ESTATE then disallow passing the contactMethod object

Here are my failed attempts:

contactMethod: Joi.when('mainType', {
    is: 'COMMERCIAL',
    then: Joi.object()
        .keys({
            create: Joi.object({
                message: Joi.string().allow(''),
            }).required(),
        })
        .required()),
}).when('isHousing', {
    is: true,
    then: Joi.object()
        .keys({
            create: Joi.object({
                message: Joi.string().allow(''),
            }).required(),
        })
        .required(),
    otherwise: Joi.disallow(),
})

I also tried this:

contactMethod: Joi.when('mainType', {
    switch: [
        {
            is: 'COMMERCIAL',
            then: Joi.object()
                .keys({
                    create: Joi.object({
                        message: Joi.string().allow(''),
                    }).required(),
                })
                .required(),
        },
        {
            is: 'REAL_ESTATE',
            then: Joi.when('isHousing', {
                is: true,
                then: Joi.object()
                    .keys({
                        create: Joi.object({
                            message: Joi.string().allow(''),
                        }).required(),
                    })
                    .required(),
            }),
            otherwise: Joi.disallow(),
        },
    ],    
})   

So what am I doing wrong here?

Answer 1

Okay, so here's how I solved it:

contactMethod: Joi.when('mainType', {
        is: 'COMMERCIAL',
        then: Joi.object()
            .keys({
                create: Joi.object()
                    .keys({
                        message: Joi.string().allow(''),
                    })
                    .required(),
            })
            .required(),
        otherwise: Joi.when('isHousing', {
            is: true,
            then: Joi.object()
                .keys({
                    create: Joi.object()
                        .keys({
                            message: Joi.string().allow(''),
                        })
                        .required(),
                })
                .required(),
            otherwise: Joi.forbidden(),
        }),
    })

My attempts didn't include the keys({}) as suggested by @hoangdv above + I also needed to change disallow() to forbidden.

Hope this helps somebody in the future.