model validation errors not rendered with render :action => "index" - ruby-on-rails

Question

I am working on a simple youtube list app where the user can add videos to the list. I am validating for the presence of the video_id field.
class Track < ActiveRecord::Base
attr_accessible :title, :thumbnail_url, :video_id
validates :video_id, :presence => true
end
i have the following create function defined in my controller:
def create
#fetches the video info, stores it in #trackinfo
if is_url(params[:track][:query])
#trackinfo = getTrackInfo(params[:track][:query])
else
#trackinfo = youTubeQuery(params[:track][:query])
end
#use #trackinfo to create track object
#track = Track.new(#trackinfo)
#tracks = Track.all
#video_ids = Track.pluck(:video_id)
if #track.save
else
render :action=>"index"
end
end
in my index.erb.html i have the following block:
<%= render partial: "error_message" %>
the corresponding _error_message.erb.html just contains the error messages from the validation:
<% if #track.errors.any? %>
<% #track.errors.full_messages.each do |msg| %>
<%= msg %><br>
<% end %>
<% end %>
the problem is when the validation fails, i am not able to see the error message from the rendered view. I logged the messages right before it entered the render index, and was able to see the messages:
from the controller:
if #track.save
else
puts "#{#track.errors.full_messages}" #i am able to see this
render :action=>"index"
end
i dont know what happens during the render causing the error messages not to be displayed, on the server logs it does say that the _error_messages.erb.html has been rendered, but i just dont see anything happen to the page. I feel like i have missed something really obvious. anyone knows what i should do?
Thanks

Answer 1

i think i resolved this issue, but im not sure if my fix is proper. I forgot to mention that on the main index.erb.html i have a search bar and a submit buttom embedded in an ajax form that calls the create function inside the controller
<%= form_tag(#track, :remote=>true, :method => :post, :class => 'new_track') do %>
<%= text_field_tag "track_query", nil, :placeholder => 'enter a query or a link', :id => "search_bar", :name => "track[query]", :size => 30, :required => true %>
<%= submit_tag "add" , :name => 'commit'%>
</p>
<% end %>
i also now have the error div in the same page (I deleted the render partial and just stuck an empty div to be populated in the index.erb.html):
<div id = "error_message">
</div>
in the file create.js.erb, I added the following lines:
<% elsif #track.errors.any? %>
if($.trim($("#error_message").html())==''){
<% #track.errors.full_messages.each do |msg| %>
$('#error_message').hide().append('<%= msg %>');
<% end %>
$('#error_message').fadeIn();
}
$('#search_bar').val('');
it seems that when i remove the render :action=>"index" completely from my create function in the controller, the error messages were able to be displayed on the index page. I was hoping to not put so much processing on the client javascript side and more on the controller side. Is there another way to do this? Still wondering why the render did not render that partial html. is it because the form is ajax and wont render the whole page? i apologize if i dont exactly know what im talking about :)