Haml: Append class if condition is true in Haml

Question

If post.published?

.post
  / Post stuff

Otherwise

.post.gray
  / Post stuff

I've implemented this with rails helper and it seems ugly.

= content_tag :div, :class => "post" + (" gray" unless post.published?).to_s do
  / Post stuff

Second variant:

= content_tag :div, :class => "post" + (post.published? ? "" : " gray") do
  / Post stuff

Is there a more simple and haml-specific way?

UPD. Haml-specific, but still not simple:

%div{:class => "post" + (" gray" unless post.published?).to_s}
  / Post stuff

score 336 · Accepted Answer · answered Aug 11 '10 at 00:50

336

.post{:class => ("gray" unless post.published?)}

answered Aug 11 '10 at 00:50

Nathan Weizenbaum

3,376
1
15
2

76

just a side note for multiple conditions ` {class: [('class1' unless condition1), ('class2' if condition2)]} ` .. etc – Mohammad AbuShady Jan 28 '14 at 11:21
6

More succinct for multiple conditions: `{ class:[ (:class1 if cond1), (:class2 if cond2) ] }` – Phrogz May 02 '15 at 19:19
3

Note: the parentheses are required or you will get ruby syntax error. – Topher Fangio May 10 '17 at 22:00
Updated json-style notation: ```.post{class: ("gray" unless post.published?)}``` – Robert Travis Pierce Dec 29 '20 at 16:46

yfeldblum · Answer 2 · 2014-09-01T05:09:45.457

22

- classes = ["post", ("gray" unless post.published?)]
= content_tag :div, class: classes do
  /Post stuff

def post_tag post, &block
  classes = ["post", ("gray" unless post.published?)]
  content_tag :div, class: classes, &block
end

= post_tag post
  /Post stuff

edited Sep 01 '14 at 05:09

answered Aug 10 '10 at 21:37

yfeldblum

65,165
12
129
169

1

Not so concise, but looks better than other ways if put into a helper. – Simon Perepelitsa Aug 10 '10 at 21:57
3

This works well - I noticed that you don't need the `.compact.join(" ")` though. You can simply do `:class => ["post active", ("gray" unless post.published?)]` – Stenerson Aug 31 '14 at 14:00

mark · Answer 3 · 2010-08-11T05:37:03.690

15

Really the best thing is to put it into a helper.

%div{ :class => published_class(post) }

#some_helper.rb

def published_class(post)
  "post #{post.published? ? '' : 'gray'}"
end

edited Aug 11 '10 at 05:37

answered Aug 10 '10 at 21:32

mark

10,316
6
37
58

I've put this in my helper file, but my app tells me, that there is no "post" variable. – Simon Perepelitsa Aug 10 '10 at 22:16
2

fyi: if you only want to include a class in a certain case and nothing in other cases you can just set `nil` and the attribute will not be set, instead of setting `class=""` – MMachinegun Aug 07 '14 at 10:45

score 14 · Answer 4 · answered Jun 10 '15 at 17:40

14

HAML has a nice built in way to handle this:

.post{class: [!post.published? && "gray"] }

The way that this works is that the conditional gets evaluated and if true, the string gets included in the classes, if not it won't be included.

answered Jun 10 '15 at 17:40

Jared

2,408
2
19
33

score 6 · Answer 5 · answered Sep 14 '18 at 05:35

6

Updated Ruby syntax:

.post{class: ("gray" unless post.published?)}

answered Sep 14 '18 at 05:35

Drew Haines

61
1
3

Haml: Append class if condition is true in Haml

5 Answers5

Linked

Related