[13.x] Improved empty and whitespace-only string handling in Blade component attributes

[NickSdot]

Closes #57463
Related #31994

 @php($foo = "")
 <x-link :title="$foo">Blub</x-link>

<a {{ $attributes }}>Blub</a>

renders as

<a title>Blub</a>

which is wrong. Title isn't a boolean attribute. It should be

<a>Blub</a>

We only ever want to have empty strings or whitespace-only strings in these situations:

• alt
• value
• data-*

Never for title, rel, placeholder, class etc.

Everything in our #57235 supi dupi mega thread points to that we want Laravel data attributes to be somewhat aligned with what Vue does (cc @timacdonald). So, if we want that, we should start here. Though, Vue doesn't allow :title="item.value" so the exceptions I added only make sense but Vue doesn't have them. That said, given how Blade component attributes work, I believe we surely don't want to introduce a whole new defaults-concept in #57235, but mirror what we already have in Blade component attributes. Not sure if Tim agrees, but I believe consistency within the framework is more important than what Vue does (this is mainly about boolean behaviour) . So, if this is merged we have one thing less to worry about in the other PR.

[taylorotwell]

@NickSdot how does this align with my comment on the @maybe PR?

Personally I think we should just follow what @timacdonald suggested on this, while leaning towards Vue for behavior where there are differences. 👍

[NickSdot]

@NickSdot how does this align with my comment on the @maybe PR?

Personally I think we should just follow what @timacdonald suggested on this, while leaning towards Vue for behavior where there are differences. 👍

It adjusts empty/whitespace strings towards Vue like Tim suggested there. 👍

@timacdonald mind to confirm that you would agree on the exceptions I added?

Though, Vue doesn't allow :title="item.value" so the exceptions I added only make sense but Vue doesn't have them.

---

I didn't touch booleans in here. That sounds like a much bigger breaking change and given how controversial (🤯) it is in the @maybe PR we might not wanna do that? But that's your call.

I somewhat think and hope Tim will agree on the boolean stuff when he saw the last context I added after his proposal.

Anyway, that's not really relevant for this one. Can follow up later. 🤝

[NickSdot]

I preferred to close the @maybe PR. However, this one stands on its own since the current behaviour is broken either way.

For completeness: Tim might want to replace this fix with Blade::compileAttribute() later in case you go forward with his proposal. But I believe the behaviour wouldn't be any different. 🙏