Correct way to access nested parameters

Rails
1

notice.rb:

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

_notice.html.erb:

<%= 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.id %>
.
.

notices_controller.rb:

@notice = @character.notices.build(notice_params)
if @notice.save
  if

!params[:notice][:active_comment_relationship][:commentee_id].nil? #
THE OFFENDING LINE
@notice.create_comment(params[:notice][:active_comment_relationship
][:commentee_id])
end
end

def notice_params
  params.require(:notice).permit( :content, :picture, :latitude, :

longitude, active_comment_relationship_attributes: [:commentee_id] )
end

The code above gives the following error:
undefined method `[]’ for nil:NilClass

Sometimes a notice is submitted with a blank/nil :commentee_id, so I
would
have thought
!params[:notice][:active_comment_relationship][:commentee_id].
nil?
would have worked. How do I write this correctly? How do you correctly
access nested parameters?

2

On 2 August 2015 at 21:15, Bazley [email protected] wrote:

@notice = @character.notices.build(notice_params)

:longitude, active_comment_relationship_attributes: [:commentee_id] )
!params[:notice][:active_comment_relationship][:commentee_id].nil?
would have worked. How do I write this correctly? How do you correctly
access nested parameters?

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

3

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: notice.id %>
<% 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-#{notice.id}”,
class: “comment_area” %>
<%= f.submit( “Post”, class: ‘btn btn-default btn-xs’,
onclick: “return
validateCommentForm(’#commentField-#{notice.id}’);” ) do %>

<% end %>
<%= f.file_field :picture, accept:
‘image/jpeg,image/gif,image/png’ %>
<% end %>

4

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.

Liz

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

5

@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 @notice.save
puts params.to_yaml
if
!params[:notice][:active_comment_relationship][:commentee_id].nil? #
THE OFFENDING LINE
@notice.create_comment(params[:notice][:active_comment_relationship
][:commentee_id])
end
end

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?
…