controller.rb

# The controller method for the same is as below

  def update_additional_details
    @user = current_user
    @user.profile.display_education_details(show_details_for_profile?(:education))
    @user.profile.display_experience_details(show_details_for_profile?(:experience))
    @user.profile.display_linkedin_details(show_details_for_profile?(:linkedin_profile))
    @user.profile.detail[:linkedin_profile][:data] = params[:linkedin_profile_data]
    if @user.profile.save
      redirect_to additional_details_user_path(@user), :notice => _("successfully_updated")
    else
      # there are errors, do not redirect the user, just render the form (template) they just submitted
      render 'edit' # or whatever template they were just looking at 
    end
  end

file.rb

class Profile < ActiveRecord::Base
  belongs_to :user

  # SERIALIZED ATTRIBUTES
  serialize :detail, Hash
  # Serialized Preferences column - uses UserPreference class.
  serialize :preferences, ProfilePreference

  # VALIDATIONS
  validate :url_valid, :on => :update

  def url_valid
    url = URI.parse(get_linkedin_profile)
    unless %w( http https ).include?(url.scheme) && (url.hostname.include? "linkedin") && !url.path.blank?
      errors.add(:detail, "Please Enter a Valid Linkedin Profile URL")
    end
  rescue URI::InvalidURIError => e
    errors.add(:detail, "Please Enter a Valid Linkedin Profile URL")
 end
 
end


=begin

In the view I have something like this 

= simple_form_for(@user, :url => update_additional_details_user_path(@user), ) do |f|
  fieldset
    = render "shared/error_messages", :target => @user

Its actually user.profile so I am passing user object and shared/error_messages looks like this :

- if target.errors.any?
  #errorExplanation.alert.alert-error.inline_notification
    h5 = _("activerecord.errors.template.header", :model => target.class.model_name.human, :count => target.errors.size)
    ul.unstyled
      - target.errors.full_messages.each do |msg|
        li = msg

=end