Adding span tag in Rails link_to
link_to can take a block so I think you're after something like this:
<%= link_to '#', :class => 'button white' do %> <span id="span">My span </span><%= @user.profile.my_data %><% end %>
A combination of the .html_safe with #{@user.profile.my_data} should work as well.
<%= link_to "<span id='span'>My span </span>#{@user.profile.my_data}".html_safe, "#", class: 'button white' %>You can also use a content_tag so it would look like:
<%= link_to(content_tag(:span, "My span ", id:"span")+"#{@user.profile.my_data}", "#", class: 'button white' %> They're basically identical but one might be easier on the eyes for you. Also, I'm pretty new to coding so if this is dead wrong for some crazy reason, please just comment and I'll change it. Thanks.
link_to '#', :class => 'button white' do <span id="span">My span </span>My dataend