Feature Request: add a Custom linktype to the Link field

[maxfenton]

Following the instructions on the Craft 5 Link field docs, I added a custom Link Type with EVENT_REGISTER_LINK_TYPES and it's working, but I kindof want to explain what I needed and nerdsnipe Pixel & Tonic into adding it.

Why: we're migrating a lot of fields on a lot of sites from Typed Link Field to Craft's Link field and both Typed Link Field and Hyper have a Custom type that does not validate that the URL begins with http(s):// nor does it add a pattern or prefix (e.g. tel:) — and we need this for sms: links. To match those plugins (and ease our migration from one of them):

Please consider adding a linktype Custom that has no urlPrefix, no pattern, and inputAttributes of type text and inputmode url

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For additional reference, see this conversation about migration from Typed Link Field to Craft Link field which includes community migration scripts that (necessarily) omit Custom links:
sebastian-lenz/craft-linkfield#286

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What I've done in my custom module:

modules/customlinktype/CustomLinkType.php

private function attachEventHandlers(): void
    {
        Event::on(Link::class, Link::EVENT_REGISTER_LINK_TYPES, function (RegisterComponentTypesEvent $event) {
            $event->types[] = 'modules\\customlinktype\\linktypes\\Custom';
        });
    }

modules/customlinktype/linktypes/Custom.php

<?php

namespace modules\customlinktype\linktypes;

use Craft;
use craft\fields\Link;
use craft\fields\linktypes\BaseTextLinkType;

/**
 * Custom text link type.
 */
class Custom extends BaseTextLinkType
{
    public static function id(): string
    {
        return 'custom';
    }

    public static function displayName(): string
    {
        return Craft::t('app', 'Custom');
    }

    protected function urlPrefix(): string|array
    {
        return '';
    }

    protected function inputAttributes(): array
    {
        return [
            'type' => 'text',
            'inputmode' => 'url',
        ];
    }

    protected function pattern(): string
    {
        return '';
    }
}

[brandonkelly]

For the sms: case, we could just add a “SMS” link type, which makes as much sense to have as “Phone” I think.

We could also loosen up “URL” validation, to allow for arbitrary URL schemes.

[Tim-Wils]

Nice, loosening up the URL validation seems to be the most complete solution :)

[maxfenton]

A more loose URL that could handle sms: would work for my use cases

Here's a real world URL example: sms:741741&body=HOME

Just did two Typed Link -> Craft Link migrations today on sites that don't have any sms: links and realized there's also no Site linktype for a Link to the baseUrl of another Site, but was able to kludge those with URL links to / and /es