Interpolating boolean attributes in HEEx

It is OK to assign to multiple dynamic attributes at once, using the syntax of your last example.

However, the result is expected to be a keyword-list or a map. Currently you are returning a single string.

Instead, you can do, for instance:

<input type="checkbox" name="web_pages[]" value={w.id} {if w.id in @selected, do: %{checked: true}} />

However, in neither case will the result be a valueless attribute.
I don’t think this is a bad thing. Instead, not supporting this special case makes it easier for the HEEx parser to always generate correct HTML.

<input type="checkbox" checked={@boolean}> should just work.

Makes sense, I would prefer to be able to generate valueless attributes like checked instead of checked=true but it’s not that important, just checking if there was a way to do that.

Thanks!

I’ve no heex project at hand to check, but I’m quite confident it just generates a valueless attribute or no attribute.

Ah! It does! The following works as expected, generating a valueless attribute for true or no attribute for false.

<input type="checkbox" name="web_pages[]" value={w.id} checked={w.id in @selected} />

Awesome, thanks!

Here is a Surface reference on boolean attributes. Is there corresponding documentation in Phoenix Liveview on this subject that we can reference?

Surface (surface-ui.org)