Rails - Oct 2011 - AJAX vote update for a nested resource

I created a house scaffold which has many reviews and the reviews can be
voted on.  All the reviews for a house are shown on the house show page.
Then each review has a vote button and a display to show the current
number of votes.  I would like the vote button to vanish and the vote
count to change by AJAX after each vote.


# reviews/_rev.html.erb
<% @house.reviews.each do |review| %>
posted <%= time_ago_in_words review.created_at %> ago by
<%review.user.username %> |
 <p id=''votes''><%= pluralize(review.votes_count,
''vote'') %></p>

<% if current_user  %>
<%= form_for(@vote, :remote => true) do |f| %>
<%= f.hidden_field "review_id", :value => review.id %>
<%= f.hidden_field "user_id",   :value => current_user.id %>

<%= f.submit "vote" %>
.
.
.



#votes controller
 def create

    r = params[:vote][:review_id]
    @review = Review.find(r)
    @vote = @review.votes.build(params[:vote])
    @vote.user_id = current_user.id

    respond_to do |format|
      if @vote.save

        format.js {   }



#create.js.erb
$(document).ready(function(){
 alert(''voted'');

});


$("#votes").html("<%= review.votes_count %>")


As it stands now, the vote will be posted but the AJAX will not work.
It will say undefined variable ''review''.

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You''re defining @review as an instance variable, so you have to use it
as
one in the view:

$("#votes").html("<%= *@*review.votes_count %>")

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That doesn''t quite work.  When I use <%= @review.votes_count %>
in the
create.js.erb file it updates the counter on the first review, 
regardless of whether the vote was placed on the first review or not.

I thought maybe if I loop through the reviews again the create.js.erb 
file it might work.

<% @house.reviews.each do |review| %>
$("#votes").html("<%= review.votes_count %>")
<% end %>

This did not work either.

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That''s to be expected with your HTML.

What you currently have will generate HTML that looks like the following if 
you have 3 reviews:

<p id=''votes''>1 vote</p>
<p id=''votes''>2 votes</p>
<p id=''votes''>3 votes</p>

$("#votes").html("3 votes")
$("#votes").html("4 votes")
$("#votes").html("5 votes")

See the problem?

The problem is that each paragraph tag has the same ID. jQuery will only 
update the first one. Each paragraph needs to have a unique ID, then your 
JavaScript to update the paragraph needs to update the specific unique ID.

Including the primary key in the HTML ID is a good solution:

<p id="review_<%= review.id %>">

Then your jQuery can update the specific paragraph that it needs to:

$("#review_<%= review.id %>").html("<%=
review.votes_count %>")


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I''m not sure why it still isn''t working for me.

<p id="review_<%= review.id%>"><%=
pluralize(review.votes_count, ''vote'')
%></p>


create.js.erb
$("review_<%= @review.id %>").html("<%=
@review.votes_count %>")

I don''t see any errors in the log.

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Solution:

<% @house.reviews.each do |review| %>
$("#review_<%= review.id %>").html("<%=
pluralize(review.votes_count,
''vote'') %>");
<% end %>

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