How do I make dynamic ids in Haml?

Question

#item

creates a div with id="item"

.box#item

creates a div with class="box" and id="item"

.box#="item "+x

creates a div with class="box" and a comment '#="item"+x'

.box#
  ="item"+x

throws "Illegal element: classes and ids must have values."

How do I get set the id to a variable?

Answer 1

There are two ways:

The long form way (define the id as if it were a regular attribute):

.box {:id => "item_#{x}"}

produces this( x is what ever x.to_s evaluates to):

<div class="box" id="item_x">

The short form way:

.box[x]

produces the following assuming x is an instance of item:

 <div class="box item" id="item_45">

See the HAML reference for more information.