parameters missing in update action rails - ruby-on-rails

Question

What is causing this update action to not work? When I debug the controller all instance variables appear to contain the correct data, but i am left with an error param is missing or the value is empty
This is the abridged form
= simple_form_for [:admin, #job, #new_delivery] do |f|
- if jdc.new_record?
%tr
%td
.......
= f.input :quantity, label: false
......
= f.submit "Add", class: "btn btn-s btn-default"
- else
%tr
%td
.......
= jdc.delivery_cost.unit
%td
.........
%td
= link_to 'Delete', admin_job_job_delivery_cost_path(#job, jdc), method: :delete, class: "btn btn-xs btn-danger"
%td
= link_to 'Update', admin_job_job_delivery_cost_path(#job, jdc), method: :patch, class: "btn btn-xs btn-info"
I'll add the relevant controller actions below:
def update
set_job_delivery_cost
if #job.present? && #job_delivery_cost.present?
#job_delivery_cost.update_attributes(job_delivery_cost_params)
raise #job.inspect
if #job_delivery_cost.save
flash[:success]="Changes Saved"
else
flash.now[:error]="Check for Errors"
return render('admin/client_types/edit')
end
end
redirect_to admin_job_job_delivery_costs_path(#job)
end
def set_job_delivery_cost
#job_delivery_cost ||= JobDeliveryCost.find_by(id: params[:id])
end
def job_delivery_cost_params
params.require(:job_delivery_cost).permit!
end
these are the request parameters:
{"_method"=>"patch", "authenticity_token"=>"66fRYMn6/2ges7JU75d5sWUausx8GJvM5dsNpbRxlYQ=", "action"=>"update", "controller"=>"admin/job_delivery_costs", "job_id"=>"53", "id"=>"17"}
Server logs...
Started PATCH "/admin/jobs/53/job_delivery_costs/17" for 127.0.0.1 at 2014-07-23 18:36:27 +0100
Processing by Admin::JobDeliveryCostsController#update as HTML
Parameters: {"authenticity_token"=>"66fRYMn6/2ges7JU75d5sWUausx8GJvM5dsNpbRxlYQ=", "job_id"=>"53", "id"=>"17"}
Job Load (0.4ms) SELECT `jobs`.* FROM `jobs` WHERE `jobs`.`id` = 53 LIMIT 1
JobDeliveryCost Load (0.4ms) SELECT `job_delivery_costs`.* FROM `job_delivery_costs` WHERE `job_delivery_costs`.`id` = 17 LIMIT 1
Completed 500 in 6ms
ActionController::ParameterMissing - param is missing or the value is empty: job_delivery_cost:
delivery cost.rb
# == Schema Information
#
# Table name: delivery_costs
#
# id :integer not null, primary key
# title :string(255)
# unit :string(255)
# cost_per_unit :float
# created_at :datetime
# updated_at :datetime
#
class DeliveryCost < ActiveRecord::Base
UNIT_DAY='day'
UNIT_HOUR='hour'
UNIT_MILE='mile'
UNITS=[UNIT_DAY,UNIT_HOUR,UNIT_MILE]
has_many :job_delivery_costs
has_many :jobs, through: :job_delivery_costs
validates :cost_per_unit, presence: true
validates :unit, inclusion: UNITS
validates :title, presence: true
before_destroy :survive_if_jobs
private
def survive_if_jobs
jobs.empty?
end
end
job_delivery_cost.rb
# == Schema Information
#
# Table name: job_delivery_costs
#
# id :integer not null, primary key
# job_id :integer
# delivery_cost_id :integer
# cost_per_unit :float
# quantity :integer
# timing :string(255)
# created_at :datetime
# updated_at :datetime
#
class JobDeliveryCost < ActiveRecord::Base
TIMING_INSTALL='install'
TIMING_BREAKDOWN='breakdown'
TIMINGS=[TIMING_INSTALL,TIMING_BREAKDOWN]
belongs_to :delivery_cost
belongs_to :job
validates :quantity, presence: true, numericality: {greater_than_or_equal_to:1}
validates :timing, inclusion: TIMINGS
#validates :cost_per_unit, presence: true
validate :validate_cost_per_unit
validate :check_associates
# validate :quantity_default
before_save :init
private
def check_associates
associated_object_exists DeliveryCost, :delivery_cost_id
associated_object_exists Job, :job_id
end
def validate_cost_per_unit
if delivery_cost and cost_per_unit.blank?
self.cost_per_unit=delivery_cost.cost_per_unit
end
return false if cost_per_unit.blank?
end
def init
if self.quantity.nil?
self.quantity = 1
end
end
end

Answer 1

The error should be in your line params.require(:job_delivery_cost).permit!. It's happening because you are not actually sending the form to the update action.
You should change the line:
link_to 'Update', admin_job_job_delivery_cost_path(#job, jdc), method: :patch, class: "btn btn-xs btn-info"
with an actual submit button, something like this:
f.submit 'Update', class: "btn btn-xs btn-info"
For that to work, however, you need to change your form action and method to the update action.

Answer 2

The problem is in that the job_delivery_cost field isn't passed via params. So I see three variants of processing the variable:
Add belongs_to :job_delivery_cost to DeliveryCost, then you have to assign job_delivery_cost to either visible input, or hidden one:
Visible real input:
= f.input :job_delivery_cost
Hidden input, so you can't change it explicitly:
= f.input :job_delivery_cost, as: hidden, label: false
Try to read the value for the DeliveryCost model instance:
= f.input :job_delivery_cost, as: hidden, label: false, value_method: :job_delivery_cost
and model:
class DeliveryCost
# ...
def job_delivery_cost
# ... some code to return job_delivery_cost
end
end
Just remove requirement for job_delivery_cost field for params, and calculate it based on ids.