Partials rendering and variables between calls in rails - ruby-on-rails

Question

In my project I show last 4 comments on a post and then when someone click on the expand comments link rest of the comments should show. I have following code
<%= link_to demo_expand_comments_path(:post_id => post.id, comment_id => comment_id ), remote: true do %>
This is the link to expand comment.
<div id="comments_container_<%= post.id %>">
<%= render :partial => 'community/comments/comment_box_posts', :collection => post.comments.order('id DESC').limit(4).reverse, :as => :comment %>
</div>
Here I am rendering first 4 comments
Now when someone click on expand comments, expand_comments action is called and in expand_comment.js.erb has following code
$('#comments_container_<%= #post_id %>').prepend('<%= escape_javascript(render :partial => 'community/comments/comment_box_posts', :collection => #comments, :as => :comment) %>');
controller action
def expand_comments
#post_id = params[:post_id]
post = Post.find(params[:post_id])
#comments = post.comments.where('id < ?', params[:comment_id]).order("created_at ASC")
I need the last shown comment_id here
respond_to do |format|
format.js{}
end
end
Now what I need help is that when expand comments action is called I want to send the post id and the last comment id I am showing now.

Answer 1

There are several ways to do this. You can change your "expand comment" link as well as you render comments.
In controller:
def expand_comments
...
#comment_id = #comments.last.id
Then in expand_comment.js.erb:
$('#comments_container_<%= #post_id %>').prepend('<%= escape_javascript(render :partial => 'community/comments/comment_box_posts', :collection => #comments, :as => :comment) %>');
$('#id_of_link').attr('href', '<%= demo_expand_comments_path(:post_id => #post_id, comment_id => #comment_id ) %>');
But it is not way I like.
Don't send comment_id parameter like url parameter. You should send it by ajax request.
Remove comment_id parameter from url, store it like data-attribute:
<%= link_to demo_expand_comments_path(:post_id => post.id), data: {comment_id: #comment_id} do %>
This is the link to expand comment.
...
Note that you have to remove "remote: true" from link_to too.
Send ajax request when link clicking:
$('#id_of_link').click(function() {
$.ajax({
type: "get",
url: $(this).attr('href),
data: { comment_id: $(this).data('comment_id') },
dataType: 'script'
});
return false;
});
And update comment_id attribute when comments rendering:
$('#comments_container_<%= #post_id %>').prepend('<%= escape_javascript(render :partial => 'community/comments/comment_box_posts', :collection => #comments, :as => :comment) %>');
$('#id_of_link').data('comment_id', '<%= #comment_id %>');