Rails update form throwing "undefined method `[]' for nil:NilClass" - ruby-on-rails

Question

I'm trying to create an update form on Rails, for an object that has a foreignkey to another. However, it throws this error. I'm still very greenhorn with Ruby on Rails and have just been following a video tutorial, so I'm not quite sure how to interpret this. I am current using rails 5.0.0
In travelers_controllers.rb, below line
#prf = update_prof_params["profiles_attributes"]["0"]
throws the error
undefined method `[]' for nil:NilClass
edit.html.erb
<div class="col-md-7 col-md-offset-3 main">
<% provide(:title, "Edit user")%>
<center><h1>Update your profile</h1></center>
<%= form_for(#person) do |f| %>
<%= render 'shared/error_messages' %>
<div class="col-md-12">
<%= render 'layouts/profilefields', f: f %>
<%= f.submit "Save Changes", class: "btn btn-large btn-primary" %>
</div>
<% end %>
</div>
_profilefields.html.erb
<%= f.fields_for :profiles do |prf|%>
<!--
<% if !#profileInfo["avatar"].blank? %>
<%= image_tag #contactInfo.avatar_url(:medium).to_s, :class=>"profilePhoto" %>
<% end %>
<div class="photoPreview">
<i class="fa fa-upload photoUpload"></i>
<p id="uploadClick">Click to Upload</p>
</div>
<%= prf.file_field :avatar, accept: 'image/png,image/gif,image/jpeg, image/jpg', id: 'uploadAvatar' %>
<p class="deletePhoto">Delete</p>
-->
<%= prf.label :about %>
<%= prf.text_field :about, :class => "form-control" %>
<%= prf.label :why %>
<%= prf.text_field :why, :class => "form-control" %>
<%= prf.label :goals %>
<%= prf.text_field :goals, :class => "form-control" %>
<%= prf.hidden_field :traveler_id, value: current_traveler.id %>
<% end %>
travelers_controller.rb
class TravelersController < ApplicationController
def edit
#person = Traveler.find(params[:id])
#profileInfo = Profile.find_or_initialize_by(traveler_id: params[:id])
##profileInfo[:email] = current_traveler.email
#This builds the form
#person.build_profile(#profileInfo.attributes)
end
def show
end
def update
#prf = update_prof_params["profiles_attributes"]["0"]
#prof = Profile.find_or_create_by(traveler_id: current_traveler.id)
if #prof.update_attributes(prf)
flash[:success] = "Profile updated"
redirect_to feed_path
else # Failed. Re-render the page as unsucessful
render :edit
end
end
private
def update_prof_params
params.require(:traveler).permit(profiles_attributes: [:about, :why, :goals,
:traveler_id])
end
end
and the models
class Profile < ApplicationRecord
belongs_to :traveler, foreign_key: "traveler_id"
end
class Traveler < ApplicationRecord
# Include default devise modules. Others available are:
# , :lockable, :timeoutable and :omniauthable
devise :database_authenticatable, :registerable, :confirmable,
:recoverable, :rememberable, :trackable, :validatable
has_one :profile
end

Answer 1

In TravelersController, the method update should be used for update traveler, not profile, so you can use mass-update via nested attribute like this:
def update
#traveler = Traveler.find(params[:id])
if #traveler.update(update_prof_params)
flash[:success] = "Profile updated"
redirect_to feed_path
else # Failed. Re-render the page as unsucessful
render :edit
end
end
So the above allow you to create/update profile which belongs to traveler. Besides, ensure the nested attribute was defined in your model:
traveler.rb
class Traveler < ActiveRecord::Base
# Your code here
#....
# Make sure define this
accepts_nested_attributes_for :profile
end
Update: The permitted params should be:
def update_prof_params
params.require(:traveler).permit(profile_attributes: [:about, :why, :goals, :traveler_id])
end
As you see profile_attributes should be used instead of profiles_attributes because traveler has one profile only