Supply all props to validator as second argument

[scottbedard]

What problem does this feature solve?

Right now (2.4.4), props can be validated based on their value, but are unable to take other props into consideration. With access to a props object, we could do more complex validation.

For example, imagine a component with a foo and bar prop, where at least one of these props must be defined. Currently, this logic would have to be placed in the component's lifecycle hooks or render function. I would like the ability to keep it within the validator functions, as I think it's a more appropriate place for the logic.

What does the proposed API look like?

export default {
  props: {
    foo: {
      validator: (foo, props) => foo || props.bar
    },
    bar: {
      validator: (bar, props) => bar || props.foo
    }
  }
}

[posva]

I gave this a shot and while it's possible to add I think it could introduce some inconsistent behaviors or complexify further the validation. For example, it's weird when used with a type because you expect both rules to validate, of course, you could say that the user is responsible for the type validation inside of the validator, we could even add a warning for that, but some people may want to use both at the same time. It's a bit similar with the required attribute. For example, at the moment, the validator only runs when the required field is set to true or a value is provided.
But maybe it's just that it's late and I'm tired 😆

[scottbedard]

I'm not sure I follow your concern @posva. I don't see this feature effecting the current behavior of required or type. I could be missing something, but wouldn't they continue to behave as they currently do?

[posva]

no, they wouldn't
Right now, a non required prop with no value never runs the validator which means that in order to support your usecase, we'll have to run the validator even when a value is not provided, which will show a warning (or throw an error depending of the validator) for other people using them to actually validate the information. Basically, I think validator is the wrong place to do this.
We could maybe support a function for required that gets passed all the props:

required: ({a, b}) => a || b

But this should be stripped off on production 🤔
edit: I'm not sur letting required be a function is a good idea

[scottbedard]

Damn, I see your concern now... If one of two props is required, but neither are passed in, neither validator will ever run and no warning will be thrown. A dedicated function might be a better place for this, I'll keep brainstorming APIs. Thanks!

[yyx990803]

Closing since it seems we were not able to find a good solution for the concerns, and it is possible to implement the logic in lifecycle hooks (e.g. beforeUpdate).