Question

I have an HTML form in my Rails view

<form id="download_form" action="download">
  Username: <input type="text" name="username"> <br/>
  <input type="submit" id="submit_download_form" value="Submit">
</form> 

In Rails controller, if the length of username is greater than 10, I’d like the controller to return to the same page, and notice the user via <p id="notice"><%= notice %></p> that the length can’t be more than 10. How can I do it?

By the way, username is not an attribute in any model. It’s just a field in this form.

Answer 1

You can get the length of username by method length:

if params[:username].length > 10
  @notice = "the length can't be more than 10"
  render 'download'
end

Then in your view you can use @notice:

<p id="notice"><%= @notice %></p>