Why is String Interpolation Failing in erb Template?

Question

I have the following code in a .erb file:

<% embed='<a href="http://someurl.com/whatever">#{@webcast.name}</a>'%>

<p id="embedCode">
    <pre>
        <code>
            <%= embed %>
        </code>
    </pre>
</p>

The anchor tag is correctly displayed onscreen as text rather than rendered as a dom element, however the string interpolation is failing. The html is successfully displayed as text but #{@webcast.name} is not evaluated. If a include <%= @webcast.name => in the template, the webcast name in rendered successfully.

Answer 1

Because strings delimited with single quotation marks '' are not interpolated.

Change your code to e.g.:

<% embed = "<a href=\"http://someurl.com/whatever\">#{@webcast.name}</a>" %>

or (if you want to avoid masking the double-quote characters ")

<% embed = %(<a href="http://someurl.com/whatever">#{@webcast.name}</a>) %>

or just (thanks to Samy Dindane for the hint):

<% embed = "<a href='http://someurl.com/whatever'>#{@webcast.name}</a>" %>