Create HasPlaceholder interface

[mvysny]

Similar to HasEnabled in #3816

[pleku]

@mvysny what for would you want to use this mixin interface for ?

Even though it is very generic bit of API and works the same way for all the components, meaning that it could be thus in a mixin interface, I don't see it would add that much value.

[mvysny]

In Karibu Testing I'm allowing the user to filter the components also based on the placeholder. However, there is no unified interface that can return the placeholder for a component, and therefore I had to write the following function:

val Component.placeholder: String?
    get() = when (this) {
        is TextField -> placeholder
        is TextArea -> placeholder
        is PasswordField -> placeholder
        is ComboBox<*> -> this.placeholder
        is DatePicker -> placeholder
        is Input -> placeholder.orElse(null)
        else -> null
    }

The HasPlaceholder doesn't have to be a mixin interface, it could be just an interface with single method, String getPlaceholder(). TextField, TextArea, PasswordField, ComboBox, DatePicker can implement the interface directly; Input needs to modify the return type from Optional to String.

A simple interface would do:

public interface HasPlaceholder {
    /**
     * A hint to the user of what can be entered in the component.
     *
     * @return the {@code placeholder} property from the webcomponent
     */
    public String getPlaceholder();
     /**
     * A hint to the user of what can be entered in the control.
     * @param placeholder
     *            the String value to set
     */
    public void setPlaceholder(String placeholder);
}

[vaadin-miki]

bumping this, as it would greatly help
reasoning similar to #3241

[Vinetos]

Hello, I would have this feature too.
I saw that HasPlaceholder has existed in previous version (Vaadin 13).

I need it because I'm rewriting part of component in a 'fluent' way (.with pattern) and all xxxFields, ComboBoxes, TextAreas implements this.

It should be applied to the interfaces HasValue.

[vaadin-miki]

@Vinetos (and everyone else looking to have this functionality implemented, for that matter) - the interface HasPlaceholder (and a mixin for .withPlaceholder()) is present in SuperFields (https://github.com/vaadin-miki/super-fields/), the add-on that I am an author of

so if you do not mind using a third-party add-on, feel free to use SuperFields while this issue is still in the works :)

[vaadin-bot]

This ticket/PR has been released with Vaadin 24.3.0.alpha6 and is also targeting the upcoming stable 24.3.0 version.