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i love how rails adds code around the fields when they have errors, but what if i want to add a css class to another element in the form when there is an error, say the form label or something like that.

i looked around at the api for validations and it looked like you can check individual methods for errors. i would imagine you can do that for the fields you have validations for and write some sort of conditional that would put a class or any other html you want in there, but i'm not quite sure how to implement that. does anyone have any examples? is there a better way of doing something like that?

Assuming a simple form creating a user AR model:

<% if @user.errors[:username] -%>
  ...
<% end -%>

Hope this helps.