Having difficulty with threaded comments, using acts_as_tree

Rails
1

I’ve been having problems making threaded comments for the last few
days. Mainly with creating children and displaying the children.
Currently, I have comments shown at the bottom of my articles show view.
The top level comments work, but I do not really know how to implement a
way for users to “reply” to the top level comments and take them to a
form (the comment ‘new’ view) to create a new comment. I want the
controller to determine if the user is creating the new comment in an
article or in a comment and create the new comment as a child if its
parent is a comment. I’ve been facing multiple problems, maybe the
recursion messes up and I get an infinite loop.

Here is the articles show controller:
def show
@article = Article.find(params[:id])
@commentable = Article.find(params[:id])
@comments = @commentable.comments

@comments = @commentable.comments.paginate(:page => params[:page])

@comment = Comment.new
@title = @article.title

end

Here is my comments controller:
def show
@commentable = find_commentable
@comment = @commentable.comments.find(params[:id])

@comments = @commentable.comments.paginate(:page => params[:page])

end

def new
@commentable = find_commentable
@comment = Comment.new
end

def create
@commentable = find_commentable
if @comment.commentable_type == “Comment”
@comment = @commentable.children.create(param[:comment])
else
@comment = @commentable.comments.build(params[:comment])
end
@comment.user_id = current_user.id
if @comment.save
flash[:success] = “Comment saved.”
redirect_to @commentable
else
flash[:error] = “Error in creating comment.”

@comments = @commentable.comments.paginate(:page =>

params[:page])
render ‘new’
end
end

Here is the comment creation form:
<%= form_for([@commentable, @comment]) do |f| %>
<%#= render ‘shared/error_messages’, :object => f.object %>

<%= f.label :title %>
<%= f.text_field :title %>
<%= f.label :content %>
<%= f.text_area :content %>
<%= f.submit "Post Comment" %>
<% end %>

Here is the loop that goes through all of the existing comments:
<% unless @comments.nil? || @comments.empty? %>
<%= render :partial => ‘comments/comment’, :collection => @comments
%>
<%#= will_paginate @comments %>
<% end %>

Here is what each individual comment looks like:

<%= comment.title %> | <%= link_to "Permalink", polymorphic_path([@commentable, comment]), :action => :show %> | <%= link_to "Reply", polymorphic_path([@commentable, @comment]), :action => :new %> | <%= link_to "Edit Comment", polymorphic_path([@commentable, comment]), :action => :edit %> | <%= link_to 'Delete Comment', [[@commentable, comment]], :confirm => "Are you sure?", :method => :delete %>
<%= comment.content %>
<%= comment.user.name %>

<%= render :partial => 'comments/comment', :collection => @comment.children %>

When I click reply, I get taken to:
http://localhost:3000/articles/299/comments and not
http://localhost:3000/articles/299/comments/new. I went into rails
console and gave one of my comments a comment child, and the recursive
nature of the threaded comments gave me recursion that crashed my site.

2

your are doing a polimorphic assotiacion on the same model and another
model
, thats not needed, you only need a self referential association and a
has
many, your main problem is that you are using a polymorphic associations
where there was no need to.

you comment table should have

t.integer :article_id
t.integer :parent_id

drop the polymorphic association if the comments will only belong to
articles and install the acts_as_three gem, then you’ll be done with it.

if you want to apply comment to something else besides articles then use
the
polymorphic association bad that is not need for the
comments they just need to refer to themself.

3

you site crashed because the comment on the page article are found by
pulling the article_id from the params but you want to add childrens to
a
comment and there is no way to pull that id with the find_commentable
function

4

radhames brito wrote:

you site crashed because the comment on the page article are found by
pulling the article_id from the params but you want to add childrens to
a
comment and there is no way to pull that id with the find_commentable
function

I am having trouble following you. I have to use the polymorphic
association because my comments will be found on the Article, Profile,
and Picture models.

5

try to fix the thing i suggested in red and add a parent_id field to
the
comments table,
then make a self referencial associaction or use the acts_as_tree gem,
the
thing is along with
the polimorphic fields a comment should be able to belong to another
comment, when you try to make a comment
belong to another comment with the same association you are using for
when
it belongs to article or anything else
the migration to that polymorphic parent is lost, why ? because you are
using this function

def find_commentable
params.each do |name, value|
if name =~ /(.+)_id$/
return $1.classify.constantize.find(value)
end
end
nilend

with it you are trying to find what comments owns the new comment that
was
added as a chils.
but this

~ /(.+)_id$/

pulls from the params hash, the params hash passes the model that has
comments nested not the
comment want to attach your new comment to.

also you are calling new on something that will call new again, that is
when
you check with new to build the child
is tries to see who the parent is but you mistankenly pass the same
object.

if need more details on how to fix all this, i can try to help, but as
you
notice my english is far from perfect.

here is how the acts_as_tree gem works

6

radhames brito wrote:

try to fix the thing i suggested in red and add a parent_id field to
the
comments table,
then make a self referencial associaction or use the acts_as_tree gem,
[…]

Or rather, don’t. acts_as_tree uses an adjacency list model, which is
simple, but ridiculously inefficient to query. What you generally want
instead is awesome_nested_set, which makes it possible to retrieve all
comment threads, to arbitrary depth, with one single query.

acts_as_tree is almost never the right choice.

Best,

Marnen Laibow-Koser
http://www.marnen.org
[email protected]

7

yes but he is new to rails and there is a railscast for acts_as_tree,
thats
why i was suggesting it.

On Wed, Sep 15, 2010 at 2:03 PM, Marnen Laibow-Koser

8

:’( , but, but …

9

Are my routes correct in using this:
resources :articles, :has_many => :comments

10

Please quote when replying. It’s hard to follow the discussion
otherwise.

radhames brito wrote:

yes but he is new to rails and there is a railscast for acts_as_tree,
thats
why i was suggesting it.

So there’s a Railscast. Big whoop. :slight_smile: acts_as_tree is easy to use for
some things, but so what? Its data model – and therefore its
performance – is poor, and it can actually be harder to use than
awesome_nested_set in certain cases. Just don’t even consider it for
serious work.

On Wed, Sep 15, 2010 at 2:03 PM, Marnen Laibow-Koser

Best,
–Â
Marnen Laibow-Koser
http://www.marnen.org
[email protected]

Sent from my iPhone

11

yes do that for articles and every model that as a comment attached