It looks like a bug. In the meantime, you can replace .unknown(false) by .options({ allowUnknown: false }), just beware that it's inherited by children schemas.

Thanks Marsup.
By the way, I look up the source code and found where is this error caused. It is in /lib/base.js.

$_setFlag(name, value, options = {}) {

        Assert(name[0] === '_' || !this._inRuleset(), 'Cannot set flag inside a ruleset');

        const flag = this._definition.flags[name] || {};
        if (DeepEqual(value, flag.default)) {
            value = undefined;
        }

        if (DeepEqual(value, this._flags[name])) {
            return this;
        }
}

It is so weird to set the value to undefined when value same as the default value of flag. But once I delete this if statement, many tests failed. Please help have a check.

Hi folks. Could I work on that issue?

It's not the easiest one but sure.

Thanks @Marsup .

Hi, @LuEason I tested this code you sent using Joi 17.6.1 and it looks like it works as you expect.

It doesn't have any errors. When I print the result I get the following:

{
  value: { a: '123', b: { c: '123', f: 123 }, d: { e: '12', g: 123 }, h: 123 }
}

Maybe it was already fixed @Marsup .

@geeksilva97 that's precisely the problem, it should fail on object d because g is not allowed.

@Marsup

It looks like a bug

This is expected:

from the docs

allowUnknown - when true, allows object to contain unknown keys which are ignored. Defaults to false.

allowUknown will override any .unknown(false) settings you have

const schema = joi.object().keys({
    foo: joi.object().keys({
        bar: joi.string()
    }).unknown(false)
})

console.log(
    schema.validate({
        foo: {
            bar: "bar",
            baaz: "baaz"
        }
    })
) // "foo.baaz" is not allowed

console.log(
    schema.validate({
        foo: {
            bar: "bar",
            baaz: "baaz"
        }
    }, {allowUnknown: true})
) // valid

@LuEason

you can turn on this feature by not passing allowUnknown: true and instead add granular uknown(false) entries to the your desired keys

Local should always override global, it is imo a bug.

fair enough, i now see this is what happens in the yup lib as well

const schema = yup.object().shape({
    foo: yup.object({
        bar: yup.string()
    }).noUnknown(true)
})

console.log(
    schema.validate({
        foo: {
            bar: "bar",
            baaz: "baaz"
        }
    }, {stripUnknown: false})
) // foo field has unspecified keys: baaz