Score:0

Drupal

How to add a boolen attribute to a form?

liquidcms

7/1/23, 7:45 PM

I am trying to add the boolean attribute "novalidate" to all my forms.

I have tried numerous approaches in my theme_preprocess_form function but no luck. I see in some preprocess functions, $variables['attribute'] is an object and has methods like addClass() and setAttribute(). But in _preprocess_form it is an array. Plus setAttribute doesnt sound like it will do boolean attributes anyway.

I tried to simply override the twig template for a form and do this:

<form{{ attributes }} novalidate>
  {{ children }}
</form>

but even that outputs:

<form novalidate="">

0 + 0

theming

forms

Clive

7/1/23, 8:02 PM

`novalidate=""` is fine for the HTML spec - boolean attributes can have a value as long as it's an empty string or the same (case-insensitive) string as the attribute name. So `novalidate="novalidate"` would also be fine. If you follow those rules, the attribute's existence is taken to mean `true` regardless of the value. See https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes#boolean_attributes

Jaypan

7/1/23, 8:21 PM

You should put that as an answer Clive - it's the correct answer to the question.

Clive

7/1/23, 8:36 PM

I was in two minds @Jaypan, maybe the "proper" answer to this is one which allows Twig/Drupal to output the bare `novalidate`, even though it doesn't technically matter? Probably over-thinking it, I'll add an answer

Jaypan

7/1/23, 8:44 PM

Well, if someone comes along with that other answer, then it too can be an answer to the question. Both will be valid answers.

Inan

8/16/23, 8:22 AM

Your browsers' dev consoles usually render it as `<form novalidate="">`, but it is in fact still `<form novalidate>`. You can use the ancient method of viewing the source ("View Page Source" in Firefox and Google Chrome) to see the actual HTML markup.

Score:3

Drupal

Clive

7/1/23, 8:39 PM

You may be attempting to solve a non-issue here. novalidate="" is fine for the HTML spec - boolean attributes can have a value as long as it's an empty string or the same (case-insensitive) string as the attribute name. So novalidate="novalidate" would also be fine.

If you follow those rules, the attribute's existence is taken to mean true, regardless of the value.

See https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes#boolean_attributes for more info.

0 + 0

liquidcms

7/1/23, 8:57 PM

Yes, I figured this would work functionally although I see there are a few issues on D.org with people asking how to add "boolean attributes" as it is supported in HTML5 and was wondering if there was a way to do this the "right" way.

Clive

7/1/23, 9:19 PM

Yeah it's the sort of thing I'd want too - it's my HTML, give me what I want! But there's too much in the way that could be manipulating the HTML to worry about it IMHO. For example, when you parse HTML into a `DOMDocument`, it's held in an XML structure. Attributes can't have empty values in XML, so boolean HTML attributes are given an empty value by default, and when the doc is saved as HTML, you get what you've seen in your question. Drupal uses `DOMDocument` in various parts of the pipeline, so that might even be literally what's happening here. Too much effort to change I'd say