Rails shows non existent database records

Question

Rails shows that an instance of the Comment model exists, even though the database is empty. My code to show the Comment is

<% @post.comments.each do |c| %>
   <%= c %>
<% end %>

And from that, I get #<Comment:0x007fe971c02800> also if i do c.attributes I get {"id"=>nil, "body"=>nil, "author"=>nil, "post_id"=>37, "deleted"=>nil, "locked"=>nil, "created_at"=>nil, "updated_at"=>nil}, but the table has no records. If I change that code to

<% @post.comments.each do |c| %>
   <%= c.body %>
<% end %>

I get nothing. Maybe it has something to me using closure_tree. If it helps, here is the schema for the table:

create_table "comment_hierarchies", id: false, force: true do |t|
  t.integer "ancestor_id",   null: false
  t.integer "descendant_id", null: false
  t.integer "generations",   null: false
end

add_index "comment_hierarchies", ["ancestor_id", "descendant_id", "generations"], name: "comment_anc_desc_udx", unique: true
add_index "comment_hierarchies", ["descendant_id"], name: "comment_desc_idx"

create_table "comments", force: true do |t|
  t.string   "body"
  t.string   "author"
  t.string   "post_id"
  t.boolean  "deleted"
  t.boolean  "locked"
  t.datetime "created_at"
  t.datetime "updated_at"
end

EDIT: I fixed it by changing the form on the page to make a new comment from

<%= form_for([@post, @post.comments.build], :html => {:class => 'ui form'}) do |f| %>
          <div class="field">
            <%= f.text_area :body, placeholder: "Comment", style: "max-height: 100px;"%>
          </div>
          <p>
            <%= f.submit "Add Comment", class: "blue ui button" %>
          </p>
      <% end %>

to

<%= form_for([@post, Comment.new], :html => {:class => 'ui form'}) do |f| %>
          <div class="field">
            <%= f.text_area :body, placeholder: "Comment", style: "max-height: 100px;"%>
          </div>
          <p>
            <%= f.submit "Add Comment", class: "blue ui button" %>
          </p>
      <% end %>

Answer 1

Could you be calling @post.comments.new somewhere before this to render the comment form? This could be adding the new, non-persisted record in the association_cache.

To avoid this, you should be able to instantiate the comment as Comment.new(post_id: @post.id). This shouldn't add the comment to the association_cache. If it does, you really don't need the post_id on the new Comment. You probably have it in a hidden field anyway.