How do I execute a helper method from inside a JS ERB?

Question

I have a helper method in my dashboard_helper.rb that looks like this:

  def show_number_of_comments(node)
    if node.comments_count == 1
      "#{node.comments_count} Comment"
    else
      "#{node.comments_count} Comments"
    end
  end

In my regular dashboard#index view, I call it like this:

<h4 class="card-comments-title"><%= show_number_of_comments(node) %></h4>

But I would like to update that rendered element via AJAX whenever a new comment is added, so in my comment#create.js.erb, I would like to reference that helper method but when I try this, it doesn't work:

$('#<%= @card_id %> .card-comments-title').html('<%= show_number_of_comments(@node) %>');

But when I do this, it works:

$('#<%= @card_id %> .card-comments-title').html('<%= @comment_count %> Comments');

The issue with the latter is that it doesn't handle pluralization.

What's the best way to approach this?

Edit 1

When I say it doesn't work, this is what I mean:

NoMethodError at /nodes/5/comments
==================================

> undefined method `show_number_of_comments' for #<#<Class:0x007fbd3715e5b8>:0x007fbd3715d4d8>

app/views/comments/create.js.erb, line 5
----------------------------------------

Also, the @node object is declared in my Comments#Create like this:

  def create
    @node = Node.find(params[:node_id])
    @comment = current_user.comments.new(comment_params)
    @comment.node = @node
    @card_id = params[:card_id]
    @comment_count = @node.comments_count + 1
    current_user.events.create(action: "commented", eventable: @comment)

    binding.pry

    respond_to do |format|
      if @comment.save and @node.save
        format.js
      else
        format.js
      end
    end
  end

When I halt execution via binding.pry as above, and I try to do @node, I get the value I expect:

[1] pry(#<CommentsController>)> @node
=> #<Node id: 5, name: "Reverse Crunches", family_tree_id: 1, user_id: 1, media_id: 5, media_type: "Video", created_at: "2015-07-25 05:49:51", updated_at: "2015-07-25 21:05:34", circa: nil, is_comment: nil, cached_votes_total: 0, cached_votes_score: 0, cached_votes_up: 0, cached_votes_down: 0, cached_weighted_score: 0, cached_weighted_total: 0, cached_weighted_average: 0.0, cached_user_tag_list: nil, cached_num_user_tags: 0, cached_tagged_user_names: [], comments_count: 3>

Edit 2

Sometimes it just fails. It doesn't output any error to either the console or my server log, it just replaces the .card-comments-title with a blank value.

Answer 1

So I figured out what I wanted to do in my specific case, i.e. pluralize comment count within my JS ERB, but I haven't figured out how to use a helper_method from within my JS ERB - so this answer doesn't really answer this question.

However, I am documenting this here in case someone else has a similar issue and my solution helps them.

In my JS ERB, all I did was used the Rails method pluralize. I completely forgot about it until I typed up this question and it works like a charm.

Here is the code snippet for my create.js.erb:

$('#<%= @card_id %> .card-comments-title').html('<%= pluralize(@comment_count, "Comment") %>');

Works like a charm, but this still doesn't answer my question about referencing/using helper methods here.

Answer 2

You can also try to avoid using backend if no localisation required:

var comentsNumber = function(num){
  return (num == 0 || num > 1) ? num + " Comments" : num + " Comment"
};
var domObject = $('#<%= @card_id %> .card-comments-title');

Basically you can easily update an object via the AJAX call and trigger content to reload:

var htmlContent = comentsNumber(<%= @comment_count %>);
domObject.html(htmlContent);