Rails中方便地實現Live Validations

[img]http://www.iteye.com/upload/attachment/135954/fa4924e9-1c50-32c2-ba46-5094969e75a3.png[/img]
我不說其它的話了，直接上代碼：

class LiveValidationsController < ApplicationController
  def validate_username
    if params[:username].length > 3
      @user = User.find_by_username(params[:username])
      if @user.nil?
        @message = "<img src='/images/accept.png' alt='Valid Username' />
      else
        @message = "<img src='/images/cross.png' alt='Invalid Username' /> Name taken"
      end
    else
      @message = ""
    end
    render :partial => "message"
  end
end

頁面_message:

<%=  @message  %>

表單輸入頁面new.html.erb：

Username  <%= f.text_field :username %><span id="username_message" class="live_validation"></span>

<%= observe_field :form_username,
:url => { :controller => :live_validations, :action => :validate_username },
:frequency => 0.5,
:update => :username_message,
:with => "username"  %>

css代碼：

.live_validation{margin-left:3px;background:#EEEE00;font-size:90%;}
.live_validation img{vertical-align:middle}

ICON圖標來自這個網站：[url]http://www.famfamfam.com/lab/icons/silk/[/url]

相關鏈接：[url]http://livevalidation.com/[/url]
[url]http://dmix.ca/2009/07/simple-live-validations-in-rails/[/url]
[url]http://plugins.jquery.com/project/validate[/url]
[url]http://github.com/augustl/live-validations/tree/master[/url]