An easy way to add validators

[Artur-]

An easy way to add validators

[web-padawan]

Moved the issue to vaadin-core and labelled with "next" to research for the next generation.

We can use Lion web components validate package for some inspiration.

[Legioth]

One fundamental question is whether it's the field itself or an external "form controller" who is responsible for managing the field's validation status.

In the case of components controlled from server-side Java, the status is controlled by an external entity and any built-in validation logic is only getting in the way. The same is often also the case if you try to use 3rd party form binding libraries such as Final Form. What such solutions usually need is some way of disabling internal validation and only controlling the visual appearance (i.e. whether a required indicator is displayed and whether and error message is displayed).

[web-padawan]

Closing in favor of vaadin/web-components#81, let's continue discussion there.