The right way to find the template and replace the link in the Rails view

My goal is to find something like "b1234" in the paragraph and replace it with:

<a href=http://bugtracker.com/bug/1234>b1234</a>

I did this using a simple ruby:

"I fixed b1234 today".gsub(/(b([0-9]+))/i, '<a href=http://bugtracker.com/bug/\2>\1</a>')

It outputs:

=> "I fixed <a href=http://bugtracker.com/bug/1234>b1234</a> today" 

I have a view in rails:

<%= post.content %>

Note. I do not save HTML code in my database when creating posts.

If I do this:

<%= post.content.gsub(...) %>

I get escaped html in the output file:

&lt;a href= ... instead of <a href= ...

... And I want this behavior , I do not want users to submit HTML (iframes would be scary!).

But how can I still get the search and replace functionality that I want without sacrificing security? Maybe a Javascript approach?

Thank!