Underscore as an attribute is not rendered - used with htmx/hyperscript

[pablo8itall]

When trying to generate html that uses hyperscript in my htmx webapp Dominate does not allow me to use _ as an attribute for a tag.

>>>tag = div(_='on click do something')
>>>tag.render()  
'<div ="on click do something"></div>'

I assume its something to do with Python as typically we'd ignore named variables when they are underscores.

>>> def test(_):
...     print(_)
... 
>>> test(1)
1
>>> 

Although this just seems to be a convention and not a hard coded language feature.

[pablo8itall]

Works if you do this:

>>> tag['_']='on fix do fixin'
>>> tag.render()
'<div ="on click do something" _="on fix do fixin"></div>'

[Knio]

This is actually from here, as a way to allow leading underscores to attribute names that would otherwise collide with Python reserved words.

[pablo8itall]

Ah I see, should be straightforward to change it to leave it if it is just the "_" and remove if it is "_something"?

I'm switching to Dominate from Jinja templates, and its a good deal faster and cleaner for me.

[pablo8itall]

Regarding how Dominate handles the hyphen and underscore generally. If I add an attribute with an underscore, when is it converted to a hyphen. I see that data_something will convert to data-something at render.

This is important for htmx as it uses hx- for all its attributes.

EDIT:
Found it here:

   # Workaround for dash
    special_prefix = any([attribute.startswith(x) for x in ('data_', 'aria_')])
    if attribute in set(['http_equiv']) or special_prefix:
      attribute = attribute.replace('_', '-').lower()

I could just fork Dominate and add 'hx_' in here as well I suppose.

[Knio]

yes, hx_ could be added there. Or that logic could be revisited (how many html attrs use underscores?)

[angelsen]

Adding hx_ would handle htmx tags as they are hx-sometag.

# Workaround for dash
special_prefix = any([attribute.startswith(x) for x in ('data_', 'aria_', 'hx_')])
if attribute in set(['http_equiv']) or special_prefix:
  attribute = attribute.replace('_', '-').lower()

handle:

input(
  placeholder="Begin typing to search",
  name="search",
  hx_post=url("search", 1),
  hx_trigger="load, input changed delay:500ms, search",
  hx_target=f"#{id}",
  hx_headers=csrf_header(request),
),

[hasansezertasan]

I'm switching to Dominate from Jinja templates, and its a good deal faster and cleaner for me.

How is that going, if it's an open source project, please live a link.

[juanjo-nan]

Hi, I encountered similar issue with htmx tags, it may be interesting to add the tags that begin with hx_ to the special prefixes.

[nikalexis]

Have a look also in this pull request for HTMX (and some more) helpers / directives.

#203

[Knio]

Fixed in #210