Joi validate individual fields of nested schema
<p>I have a nested schema setup like this:</p>

<pre><code>var schema = Joi.object().keys({
  first_name: Joi.string().required(),
  last_name: Joi.string().required(),
  address: Joi.object().keys({
    street: Joi.string().required(),
    zip: Joi.number().required(),
    state: Joi.string().required(),
    country: Joi.string().required()
  }).required(),
})

var options = { abortEarly: false };

var result = Joi.validate({}, schema, options);
</code></pre>

<p>When running this, <code>result.error</code> will return the message:</p>

<pre><code>[
  {message: '"first_name" is required', path: 'first_name' }, 
  {message: '"last_name" is required', path: 'last_name' },
  {message: '"address" is required', path: 'address' }
]
</code></pre>

<p>As you see, the <code>address</code> field is not expanded. I don't want to get a message that the whole address field is missing. Instead, I want to be informed about the individual items in the address schema missing. When I don't make <code>address</code> explicitly required, the items in it don't get validated against <code>required()</code> at all. The nested field validation seems to work only on the entire nested schema object level, not on the individual items within the schema level. How do I make it work with the individual nested schema items?</p>