How do I make dynamic ids in Haml? - ruby-on-rails

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.

Answer 2

You can set the id and class in HAML the following ways
The normal way
.box.item#item
<div id="item" class="box item"></div>
If you need to interpolation you can use this format
.box{id: "item_#{123}", class: "item_#{123}"}
<div id="item_123" class="box item_123"></div>
This format generates the class and id using the object reference
# app/controllers/items_controller.rb
#item = Item.find(123)
.box[#item]
<div id="item_123" class="box item"></div>
If you need to prefix something
.box[#item, :custom]
<div id="custom_item_123" class="box custom_item"></div>
If you need a custom class and id generation you need to add the following method to model.
class CrazyUser < ActiveRecord::Base
def haml_object_ref
"customized_item"
end
end
And then you will get the customized class
.box[#item]
<div id="customized_item_123" class="box customized_item"></div>
Refer:
http://haml.info/docs/yardoc/file.REFERENCE.html#object-reference-
http://haml.info/docs/yardoc/file.REFERENCE.html