Correct way to access nested parameters


has_one :active_comment_relationship, class_name: “Commentrelationship”,
foreign_key: “commenter_id”,
dependent: :destroy
has_one :supernotice, through: :active_comment_relationship, source: :commentee
accepts_nested_attributes_for :active_comment_relationship



<%= form_tag( {controller: "notices", action: "create"}, method: "post", class: "comment_form", multipart: true ) do %>
  <%= hidden_field_tag :callsign, @character.callsign %>
  <%= hidden_field_tag "notice[active_comment_relationship][commentee_id]", %>



@notice =
  if !params[:notice][:active_comment_relationship][:commentee_id].nil? # THE OFFENDING LINE

def notice_params
  params.require(:notice).permit( :content, :picture, :latitude, :longitude, active_comment_relationship_attributes: [:commentee_id] )


Are you sure it is not active_comment_relationship that is nil? Have
a look in the log and see what it says for params. If you think it is
ok copy/paste the log for the complete transaction here.


@Colin is right. I think here that you should be asking, how can I learn the params returned?

To debug, modify. That is what I have used, others may have better suggestions:

` if
puts params.to_yaml
if !params[:notice][:active_comment_relationship][:commentee_id].nil? # THE OFFENDING LINE

puts params.to_yaml will return the structure and values to your logging.

Otherwise, you are testing too generally for uncertain aspects:``if !params[:notice][:active_comment_relationship][:commentee_id].nil?
Test each aspect for the moment to ascertain missing values:

unless `params[:notice].blank?

unless params[:notice][:active_comment_relationship].blank? ....`` unless params[:notice][:active_comment_relationship][``````:commentee_id]``.blank?



You were right, it looks like it’s active_comment_relationship is nil, I think. I added the yaml line and got this:

— !ruby/hash:ActionController::Parameters

utf8: ✓

authenticity_token: nNWNdGOzKSu5gfDkB4x3AFIO1PQnIggn65uE//SGQNzK8Ub5AOtsShH3CLZd+oU7ic9WlA+F0RbsSVR6X1I78w==

callsign: bazzer

notice: !ruby/hash:ActionController::Parameters

latitude: ‘51.75253980933651’

longitude: ‘-1.39801025390625’

content: Hello everyone

commit: Drop

controller: notices

action: create

Completed 500 Internal Server Error in 31ms (ActiveRecord: 7.1ms)

NoMethodError (undefined method `[]’ for nil:NilClass):

I have updated my code to use a form builder. It’s all working great except for this one problem. The code is below. For some reason the fields_for is not working - as the params above shows there should be an active_comment_relationship parameter for notice but it isn’t present. What’s wrong with this code?:

<%= form_for(:notice, url: :notices, method: :post, html: { multipart: true, class: "comment_form" } ) do |f| %>
  <%= hidden_field_tag :callsign, @character.callsign %>
  <%= f.fields_for :active_comment_relationship do |ff| %>
    <%= ff.label :commentee_id %>
    <%= ff.hidden_field :commentee_id, value: %>
  <% end %>
  <%= f.hidden_field :latitude,  value: notice.latitude,  id: "comment_notice_latitude"  %>
  <%= f.hidden_field :longitude, value: notice.longitude, id: "comment_notice_longitude" %>
  <%= f.text_area :content, rows: 1, id: "commentField-#{}", class: "comment_area" %>
  <%= f.submit( "Post", class: 'btn btn-default btn-xs',
                onclick: "return validateCommentForm('#commentField-#{}');" ) do %>
    <span class="glyphicon glyphicon-ok" aria-hidden="true"></span>
  <% end %>
  <%= f.file_field :picture, accept: 'image/jpeg,image/gif,image/png' %>
<% end %>


fields_for is a devil to understand, with and without a parent/data form. You need to really study the Rails documentation a lot, create scenarios from your data… Before you try fields_for you should test at ‘rails console’ for certainty that your associations are productive. Be certain of your data before testing because association testing in true null/empty is pretty nondescript… If you are bold, go to GitHub, and search to Rails applications and then fields_for…

Best to you.


PS: Write to Colin Law, he is a wealth of information regarding tutorials…