Remove defaults for optionLabel and optionValue props

[DanielleHuisman]

It is currently not possible to achieve PrimeVue's default option behaviour for optionLabel and optionValue, because null and undefined are always overridden by 'label' and 'value' respectively. This is PrimeVue's default optionValue behaviour:

Property name or getter function to use as the value of an option, defaults to the option itself when not defined.

This PR removes the defaults to restore PrimeVue's behaviour. This will break applications that rely on this behaviour, so I'm not sure what would be the best way to proceed. I can think of some options:

• Add a warning when optionLabel or optionValue is null or undefined, so existing applications are notified of the change. Adding a flag to disable the warning would be useful.
• Add a global flag to enable/disable the existing behaviour
• Release this change in the next major version (v2). As a side note: I think maintenance effort can be reduced by using v-bind instead of specifying all options separately. Such a change would be suitable for a major release.

[sfxcode]

Hello Danielle,

you are right, i will merge it for the next 1.6.x release. Global flags seems for me a overkill for this small helper library, so i will mark it at breaking change. Thank you for pointing out !

[sfxcode]

• Release this change in the next major version (v2). As a side note: I think maintenance effort can be reduced by using v-bind instead of specifying all options separately. Such a change would be suitable for a major release.

Hi Danielle, just want to let you know that the latest version 1.8.0 supports all attributes over v-bind.

Have a nice coding time,

Tom