Sometimes when writing HTML, it’d be nice to have a shortcut to create an id attribute.
In Rails views there exists the dom_id helper method that does this very thing.
It’s designed to be used with a collection of ActiveRecord items (for example, a collection of items from a database query); However, it can be used with plain objects as well.
First, let’s see how it works with a single item.
How it works
- Assuming that a Post model exists
- And that a Post with an id of 123 exists
Imagine this happens in a controller action (like index or show)
@post = Post.find(123)
In the related view, the dom_id helper method is available within embedded Ruby tags
<div id="<%= dom_id(@post) %>">
# some cool content
</div>
This would create the following HTML
<div id="post_123">
# some cool content
</div>
Customizing the id
Perhaps the value of the id would be more descriptive with some customization.
Pass a second argument as either a symbol or a string, and that word will be prepended onto the id.
<div id="<%= dom_id(@post, "edit") %>">
# some cool content
</div>
This will create the following HTML
<div id="edit_post_123">
# some cool content
</div>
Summary
For now, this is all I need to understand this concept of the dom_id helper method.