Embedded Ruby

Ruby on Rails

While this tutorial has content that we believe is of great benefit to our community, we have not yet tested or edited it to ensure you have an error-free learning experience. It's on our list, and we're working on it! You can help us out by using the "report an issue" button at the bottom of the tutorial.

The most popular way to add Ruby code inside Rails views is with embedded Ruby (ERB). Files with embedded Ruby have the extension .html.erb and these files can have any amount of regular html markup.

Here’s the basic syntax:

  <% @todo_items.each do |todo| %>
    <li><%= todo.name %> : <%= todo.priority %></li>
  <% end %>

This will output html that looks like that:

    <li>Buy milk : Normal</li>
    <li>Mow land : Urgent</li>
    <li>Throw a ball : Normal</li>
    <li>Learn Ruby : Extremely Urgent</li>

Notice the use of <% with %> or <%= with %>. These tags are used to wrap Ruby code. The code following <% will be executed, but no output will be rendered. The code following <%= will have its result outputted in the html file.

Here’s a comment in ERB. These won’t be outputted in the html at all, not even as an html comment:

<%# Wild Things %>
Creative Commons License