(rails) taking from DB and rendering into HTML

Answer 1

The h method you're calling here:

<%=h @datapost.body %>

is also known as html_escape - here's the relevant link on Railsbrain. Remove it and your HTML tags should render appropriately.

You should always display code you get from a user with the h method to prevent cross-site scripting attacks. But if it's code you scraped from a book (or whatever) it should be fine.