Haml 6 has some breaking changes Show archive.org snapshot regarding boolean attributes Show archive.org snapshot .

Only the following attributes and aria/data attributes are considered boolean attributes: allowfullscreen, async, autobuffer, autofocus, autoplay, checked, controls, default, defer, disabled, download, formnovalidate, hidden, inert, ismap, itemscope, loop, multiple, muted, novalidate, open, pubdate, readonly, required, reversed, scoped,
seamless, selected, sortable, truespeed, typemustmatch

Do you need DevOps-experts?

Your development team has a full backlog? No time for infrastructure architecture? Our DevOps team is ready to support you!

We build reliable cloud solutions with Infrastructure as code
We are experts in security, Linux and databases
We support your dev team to perform

Examples

Haml (no breaking changes)	Version 5	Version 6
%button(disabled)	`<button disabled=""></button>`	`<button disabled=""></button>`
%button(disabled=true)	`<button disabled=""></button>`	`<button disabled=""></button>`
%button(disabled=false)	`<button></button>`	`<button></button>`
%button(disabled='true')	`<button disabled="true"></button>`	`<button disabled="true"></button>`
%button(disabled='false')	`<button disabled="false"></button>`	`<button disabled="false"></button>`
%button(disabled='')	`<button disabled=""></button>`	`<button disabled=""></button>`

Haml (no breaking changes)	Version 5	Version 6
%button(data-test)	`<button data-test=""></button>`	`<button data-test=""></button>`
%button(data-test=true)	`<button data-test=""></button>`	`<button data-test=""></button>`
%button(data-test=false)	`<button></button>`	`<button></button>`
%button(data-test='true')	`<button data-test="true"></button>`	`<button data-test="true"></button>`
%button(data-test='false')	`<button data-test="false"></button>`	`<button data-test="false"></button>`
%button(data-test='')	`<button data-test=""></button>`	`<button data-test=""></button>`

Haml (with breaking changes)	Version 5	Version 6
%button(up-test)	`<button up-test=""></button>`	`<button up-test="true"></button>`
%button(up-test=true)	`<button up-test=""></button>`	`<button up-test="true"></button>`
%button(up-test=false)	`<button></button>`	`<button up-test="false"></button>`
%button(up-test='true')	`<button up-test="true"></button>`	`<button up-test="true"></button>`
%button(up-test='')	`<button up-test=""></button>`	`<button up-test=""></button>`

Monkey Patch

In case you want to reconfigure the attributes that a recognized as boolean attributes you can use this monkey patch in an initializer:

Haml::AttributeBuilder.class_eval do
  remove_const(:BOOLEAN_ATTRIBUTES).tap do |boolean_attributes|
    const_set(:BOOLEAN_ATTRIBUTES, [*boolean_attributes, /^up-/].freeze)
  end
end

Breaking changes for boolean attributes in HAML 6

Do you need DevOps-experts?

Examples

Monkey Patch