How to do data- attributes with Haml and Rails?

Question

I can have

%a{href: '#', data_toggle_description_length: 'toggle_me_ajax'}

which it gives me underscores not dashes, i.e.

<a href="#" data_toggle_description_length="toggle_me_ajax"></a>

However I want to have HTML data- attributes, i.e.

<a href="#" data-toggle-description-length="toggle_me_ajax"></a>

but when I try replacing underscores with dashes, i.e.

%a{href: '#', data-toggle-description-length: 'toggle_me_ajax'}

I get syntax errors:

/home/durrantm/Dropnot/webs/rails_apps/linker/app/views/links/_links.html.haml:13: syntax error, unexpected tLABEL
...data-toggle-description-length: 'toggle_me_ajax')}>\n    tog...
...                               ^
/home/durrantm/Dropnot/webs/rails_apps/linker/app/views/links/_links.html.haml:13: syntax error, unexpected ')', expecting '}'
...ption-length: 'toggle_me_ajax')}>\n    toggleMeAjax\n  </a>\...
...                               ^
/home/durrantm/Dropnot/webs/rails_apps/linker/app/views/links/_links.html.haml:13: unknown regexp options - pa
/home/durrantm/Dropnot/webs/rails_apps/linker/app/views/links/_links.html.haml:13: syntax error, unexpected $undefined
... toggleMeAjax\n  </a>\n</span>\n", -1, false);::Haml::Util.h...
...                               ^
/home/durrantm/Dropnot/webs/rails_apps/linker/app/views/links/_links.html.haml:13: unterminated string meets end of file
/home/durrantm/Dropnot/webs/rails_apps/linker/app/views/links/_links.html.haml:13: syntax error, unexpected $end, expecting '}'

Kore

Answer 1

Try this:

%a{"data-toggle-description-length" => "toggle_me_ajax", href: "#"}

OR

%a{href: "#", :data => {:toggle_description_length => "toggle_me_ajax"}}

For more details refer here

You can also use html2haml converter available online

EDIT:

As mentioned in comments there are a couple more syntaxes which would work

 %a{href: "#", { "data-toggle-description-length": "toggle_me_ajax" }}

OR

%a{href: "#", { :"data-toggle-description-length" => "toggle_me_ajax" }}

I would still prefer first two though as I think latter ones look ugly and kinda messy.

Roderickroderigo

+1 Nice catch! Yeah looks like rails will convert the underscore to dash for the second form. I like that second form so glad I can use it. – Kore

Any reason not to use the newer hash syntax there? (seems ok for cases I am trying). – Kore

@MichaelDurrant both will generate same html so i don't really think it matters. I just thought i should write both ways so you can choose yourself – Roderickroderigo

Another option would be to use the HTML style attributes: %a(href= '#' data-toggle-description-length: 'toggle_me_ajax'). Also converting underscores to hyphens may well be the norm in the future, not just for nested hashes as it is currently: github.com/haml/haml/issues/782. – Centuplicate

Also: { "data-toggle-description-length": "toggle_me_ajax" } or even { :"data-toggle-long-data-attribute" => "tickle_me_elmo" } if you like rockets. – Uno

Using Ruby 1.9 hashes, you can do it this way: .your_div{id: "the_id", class: "the_class", data: { some_data: "your data goes here"}} No old style hash rockets, no strings, and the data attribute is properly formatted in the HTML. – Jiggered

Answer 2

There's really not much need to use { ... } style in haml. HTML style attributes are a more flexible and natural way for html generation.

%a(href="#" data-toggle="target") my link

No commas, no hash rockets etc. are required. You can also very easily interpolate or directly assign variables without switching styles.

e.g.

%a(href=link data-toggle="#{id}-toggle")

Where link and id are variables from the currently bound scope.

Notably you can also seamlessly include attributes from xmlns, svg generation uses a lot of namespace prefixes for example:

%link(xlink:type="simple" xlink:href=link)

There's no compelling reason to use another style.

Sweven

Because there are no commas separating attributes, though, more complicated expressions aren’t allowed. For those you’ll have to use the {} syntax from haml.info/docs/yardoc/file.REFERENCE.html#htmlstyle_attributes_ – Seymour

Your templates should not have complex expressions, it adds unnecessary problems during maintenance of the app. – Sweven

Not sure why this isn't the accepted answer. This is way better than using the general-purpose syntax of Ruby for the specific task of setting HTML attributes. For all that's wrong with HTML, attribute syntax isn't really an issue. – Korfonta

@AndrewKoster mostly becuase the answer came in more than a year after the original. Note that the accepted answer now has 67 votes so not sure if I should change it anyway – Kore

Answer 3

Something like this should work really well:

%a{ "data-user-id" => "#{@user.id}" }

Diapason