title: How to properly sanitize user input server side in Phoenix
body: <p>I know how to sanitize user input client side but I would also do it on the server side. I know that the proper place to do it is using <code>changeset</code> but up to now I cannot find an example of how to do it properly for <code>&lt;script&gt;&lt;/script&gt;</code> tags and other potential harmful content like SQL injection.
  Because I want to allow users to change HTML content and save that HTML in the database I cannot use standard validation and I display <code>raw</code> HTML in the templates.
  Can someone give me an example?</p>