always force a value for a field in a schema using Joi custom validator

joi.custom.md

Joi Custom Validtion

Adds a custom validation function to execute arbitrary code

https://joi.dev/api/?v=17.4.0#anycustommethod-description

Set a null value for any data type regardless of whats given. I used this in a nested if/when statement to only trigger under certain conditions based on other key values.

Here's the gist:

const forceNullValue = (value, helpers) => {
    // we could do all sorts of cool stuff in here, like inspect `value`, returning
    // whatever custom values we want. See example in Joi documentation.
    return null
};

const schema = Joi.any().custom(forceNullValue, "ignore input and force null value validation");