"Describe" behavior changes for "implicit" Any with extended Joi

[WesTyler]

Context

• node version: 4.5.0
• joi version: 10.0.6
• environment (node, browser): node
• used with (hapi, standalone, ...): joi-date-extensions

What are you trying to achieve or the steps to reproduce ?

I know that using Joi.any().valid('value') is preferable over using Joi.valid('value'), but the behavior of .describe() is changing between the two cases when Joi is extended.

This change in describe is less than ideal for Felicity since we built off of describe() and hope to support extensions soon.

I'm using joi-date-extensions here, but it appears to be related to .extend rather than the extension itself.

const BaseJoi = require('joi');
const JoiDate = require('joi-date-extensions');
const ExtendedJoi = BaseJoi.extend(JoiDate);

// What I wish users would do, but cannot guarantee:
ExtendedJoi.any().valid('type').default('type').describe();
/*
{ type: 'any',
  flags: { allowOnly: true, default: 'type' },
  valids: [ 'type' ] }
*/

// How I expect the extended Joi to continue to behave:
BaseJoi.valid('type').default('type').describe();
/*
{ type: 'any',
  flags: { allowOnly: true, default: 'type' },
  valids: [ 'type' ] }
*/

// Actual extended Joi behavior. Flags and valids are dropped
ExtendedJoi.valid('type').default('type').describe();
/*
{ type: 'any' }
*/

[WesTyler]

I'm currently looking into this, but wanted to submit the issue in the meantime in case anyone has input on the issue :)

[WesTyler]

It looks like ExtendedJoi.valid('type').describe() invokes the root.describe here, and the ternary is defaulting to the false case, which is a new Any():
const schema = arguments.length ? root.compile(arguments[0]) : any;

[WesTyler]

Ok, it looks like it may just be too bad.

When BaseJoi.valid('type') is called, BaseJoi is returning an instance of (new Any()).clone() (here), which is why the "implicit" any behavior works.

But! When ExtendedJoi.valid('type') is called, the root class is returned (here and here). That's why when .describe() is called, it behaves as BaseJoi.describe() instead of any().describe().

I'm going to leave this open for visibility and just in case I misunderstood something, but I think it is a dead end without re-implementing extend.

[WesTyler]

Closing this out now. Not sure why I felt the need to leave it open for so long.

[Marsup]

I'm not sure what to do with this, this is definitely a bug, but I don't yet see a way out of it.

[Marsup]

OK, found a way, never talk too soon :)
I'll get on it after diner, maybe expect a new release in the week-end if I'm motivated.

[WesTyler]

Oh, nice! :D

I couldn't find a way out of it either. My only "solution" was essentially a breaking change rewrite of how extend works... So I'm glad you found a way!

[Marsup]

It doesn't seem to break anything but who knows :D