Add <none> placeholder to clear / unset inherited value

@damienmckenna just came back here for the same needs. The question is, do you think it will be realistic to implement the full featured override solution within the next decade? :D (Not asking you do do so or something like that, this is really meant to read with a smile).

My thought is the following:
I think needing to clear a predefined default in an override is clearly an edge-case.
It already works for any kind of string, it's just not possible to unset a value at higher level, because clearing the value would bring back the defaults. And entering a space would (hopefully) just set a space for the metatag value.

So if we'd allow a special string like
<unset>
<empty>
<none>
for technical users, we could quite simply extend the overriding to this remaining case.
And we could still convert that into checkboxes one day, if anyone solves it.

If you should change your opinion on this, our team would be happy to implement that, as we're running into this again and again.

Implementing the full-featured checkbox solution is great, but a big bunch of work and risky to never getting done.
This might be just "good enough" and fit things like Drupals magic "code> placehoder.

Reopening this as a simpler solution that won't involve greatly expanding the DOM structure and JS logic on edit forms.

So something like this might work, maybe?

Hi Damien, thanks, I'll take a look asap, bookmarked this!

Works great! Thanks for the fix @damien!

I basically copied the example by @anybody, and it works like a charm! The canonical url will get removed on 403 pages if we declare it as .

I'll add a test for this.

To be honest, I don't quite get this request and how the inheritance works for metatags?

Based on the request, it sounds like, if we would set the metatag value of a child metatag to an empty string (e.g. setting the 403 canonical_url to ""), the metatag would use the parents value (global's canonical url). But this isn't the case.

Setting an empty string instead of already does the exact same thing. This is also represented in code and the currently failing tests.

    // If there is no value, just return either an empty array or empty string.
    if (is_null($this->value) || $this->value == '') {
      return [];
    }

    // Support the "<none>" option to hide all output for this meta tag.
    if (!is_array($this->value) && $this->value == '<none>') {
      return [];
    }

And how does the whole inheritance work then?

403

Inherits meta tags from: Global

I don't think it does.

If we allowed to set an empty string, inherit the value from the parent and delete the metatag, @thomas.frobieter, and I suggest having the following changes:

• Add the ability to provide <none> as value, to kill the metatag entirely.
• Add the ability to provide <empty> as value, to let the metatag have an empty string.
• Add the ability to provide to leave the input empty to use the parent value (inherited).

Note, that the inherit / empty string functionality could also be implemented via checkbox.

Thanks, I'll check that!

@Grevil: Like just tested together I can not confirm this. Having an empty value leads to inheritance (as expected)!

All done, please review.

Yea, this whole endeavour was caused, because programmatically setting a metatag value to an empty string will kill the metatag output entirely, resulting in the same behaviour as providing <none> (which is the root cause of my confusion).

Only if we set an empty string via UI, the submit call will silently override our empty string with its parent value. That is also, why the tests failed originally. This is REALLY confusing! ESPECIALLY if there is also an empy / isNull check on the ouput handler and no way to tell, that $this->value will silently get overriden on submit...

Super nice @grevil thank you! Works fine and as expected now. Please open a follow-up to reduce the confusion you described.

Next step (UX-wise) should be ✨ Inherit parent metatags as placeholder in override forms Active

Created the follow-up issue here: 📌 Set metatag parent programmatically (inherited value) Active .

What about values coming from <select> ?
We have some in the Twitter card, but mostly in Schema.org Metatag module that use a lot of them.
Is there a way to automatically add <none> to the <select> or this is due to this module ?