First and last objects in rails collection -

in application have "students" partial, passes collection of @students "student" partial. these displayed on index page images of students. when user clicks on image, i'm poping box student's photo , text. now, have previous/next button allows users cycle through students. implemented cycling w/out plugin...just simple ajax call load next/previous object. problem cannot detect when i'm @ last (or first) record. need way set url parameter on first , last objects. this: www.mysite.com/students/15?last=true

i couldn't find clean way this. i'm not sure if i'm thinking right way. should attaching url parameters? or should somehow modify object add additional attributes after retrieving them model?

thank you.

[edit]

just wanted make little clearer. when pop students lightbox, have 2 links: previous (linking previous record) , next linking next record. i'm using jquery $.load method make ajax request , load in data want, div in lightbox, whenever click previous or next.

$('previous').click( $('mydiv').load('url of previous student'); );

i 'url of previous/next student' walking dom tree on initial pop up. store these can refer them again.

my problem cannot tell when i'm @ first student in list or last. need know can disable prev/next button. i'm thinking can either through rails/ruby or through javascript. initially, thought adding url parameter on link or previous/next student (to indicate whether first or last), detect in rails , simple if/else disable links. got stuck @ trying way i'm referring partials.

ehm, way inspiration,maybe you: student/index classic index file ajax loading list, will_paginate , code wrote above. every student have image link, link has href /student/4 , remote: true.

student show controller

@student = student.find(params[:id]) 

student show js file classic js render "student"

student _student.html.erb view , 2 view helper: prev_help(params[:id]) , next_help(params[:id])

helpers:

def prev_help(id)     @student = student.find(id - 1)     link_to("prev". @student )  if @student.nil?         end  def next_help(id)     @student = student.find(id + 1)     link_to("prev". @student )  if @student.nil?         end 

i don't have time now, if solution not you, can write me tomorrow , i'll create sample app test solution , colaborate you.