Association not recognized, undefined method error - ruby-on-rails

Question

I created 2 scaffolds 'mepager' and 'pimp' and linked the models like this:
class Mepager < ActiveRecord::Base
belongs_to :pimp
end
class Pimp < ActiveRecord::Base
has_one :mepager
end
I added following lines to my routing:
resources :pimps do
resources :mepagers
end
And my mepager create action looks like this:
def create
#mepager = #pimp.build_mepager(mepager_params)
respond_to do |format|
if #mepager.save
format.html { redirect_to #mepager, notice: 'Mepager was successfully created.' }
format.json { render action: 'show', status: :created, location: #mepager }
else
format.html { render action: 'new' }
format.json { render json: #mepager.errors, status: :unprocessable_entity }
end
end
end
And for #pimp to set
def setPimp
#pimp = Pimp.find_by_id(:pimp_id)
end
But if I try to create a new mepager at pimps/1/mepagers/new I get an undefined method build_mepager error.
undefined method `build_mepager' for nil:NilClass
I tried the same in the rails console and it worked with just that method. So I guess somethings still missing to make it work on my web application.
Btw I m using rails 4.0.0
Regards!
Routing
Prefix Verb URI Pattern Controller#Action
pimps GET /pimps(.:format) pimps#index
POST /pimps(.:format) pimps#create
new_pimp GET /pimps/new(.:format) pimps#new
edit_pimp GET /pimps/:id/edit(.:format) pimps#edit
pimp GET /pimps/:id(.:format) pimps#show
PATCH /pimps/:id(.:format) pimps#update
PUT /pimps/:id(.:format) pimps#update
DELETE /pimps/:id(.:format) pimps#destroy
root GET / pimps#index
pimp_mepagers GET /pimps/:pimp_id/mepagers(.:format) mepagers#index
POST /pimps/:pimp_id/mepagers(.:format) mepagers#create
new_pimp_mepager GET /pimps/:pimp_id/mepagers/new(.:format) mepagers#new
edit_pimp_mepager GET /pimps/:pimp_id/mepagers/:id/edit(.:format) mepagers#edit
pimp_mepager GET /pimps/:pimp_id/mepagers/:id(.:format) mepagers#show
PATCH /pimps/:pimp_id/mepagers/:id(.:format) mepagers#update
PUT /pimps/:pimp_id/mepagers/:id(.:format) mepagers#update
DELETE /pimps/:pimp_id/mepagers/:id(.:format) mepagers#destroy
GET /pimps(.:format) pimps#index
POST /pimps(.:format) pimps#create
GET /pimps/new(.:format) pimps#new
GET /pimps/:id/edit(.:format) pimps#edit
GET /pimps/:id(.:format) pimps#show
PATCH /pimps/:id(.:format) pimps#update
PUT /pimps/:id(.:format) pimps#update
DELETE /pimps/:id(.:format) pimps#destroy
Altered line in pimp controller
def create
#pimp = Pimp.new(pimp_params)
respond_to do |format|
if #pimp.save
format.html { redirect_to new_pimp_mepager_path, notice: 'Product Improvement was successfully created.' }
format.json { render action: 'show', status: :created, location: #pimp }
else
format.html { render action: 'new' }
format.json { render json: #pimp.errors, status: :unprocessable_entity }
end
end
end
mepager controller
class MepagersController < ApplicationController
before_action :set_mepager, only: [:show, :edit, :update, :destroy]
def setPimp
#pimp = Pimp.find(params[:pimp_id])
end
# GET /mepagers
# GET /mepagers.json
def index
#mepagers = Mepager.all
end
# GET /mepagers/1
# GET /mepagers/1.json
def show
end
# GET /mepagers/new
def new
#mepager = Mepager.new
end
# GET /mepagers/1/edit
def edit
end
# POST /mepagers
# POST /mepagers.json
def create
raise params[:pimp_id].inspect
#mepager = #pimp.build_mepager(mepager_params)
respond_to do |format|
if #mepager.save
format.html { redirect_to #mepager, notice: 'Mepager was successfully created.' }
format.json { render action: 'show', status: :created, location: #mepager }
else
format.html { render action: 'new' }
format.json { render json: #mepager.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /mepagers/1
# PATCH/PUT /mepagers/1.json
def update
respond_to do |format|
if #mepager.update(mepager_params)
format.html { redirect_to #mepager, notice: 'Mepager was successfully updated.' }
format.json { head :no_content }
else
format.html { render action: 'edit' }
format.json { render json: #mepager.errors, status: :unprocessable_entity }
end
end
end
# DELETE /mepagers/1
# DELETE /mepagers/1.json
def destroy
#mepager.destroy
respond_to do |format|
format.html { redirect_to mepagers_url }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_mepager
#mepager = Mepager.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def mepager_params
params.require(:mepager).permit(:pre, :post, :comment, :save_h, :save_c, :save_other, :save_otherv, :affect_design, :affect_stress, :affect_me, :affect_other, :affect_dno, :affect_mid, :affect_otherdoc, :owner, :pps, :reference)
end
end

Answer 1

The problem is probably here:
#pimp = Pimp.find_by_id(:pimp_id)
what you are doing is finding a pimp that has an id of the literal symbol :pimp_id (which is highly unlikely to exist)
Probably what you want is the parameter: params[:pimp_id]
EDIT:
and for the second part.
for the create action to work with a real #pimp (that can be found by :pimp_id), you must also do the same on the new action too!
Otherwise create won't work.
Can I recommend something like...
before_action :fetch_pimp, only: [:new, :create]
# GET /mepagers/new
def new
#mepager = Mepager.new
end
# POST /mepagers
# POST /mepagers.json
def create
#mepager = #pimp.build_mepager(mepager_params)
respond_to do |format|
# as previously...
end
end
# ...
private
def fetch_pimp
#pimp = Pimp.find(params[:pimp_id])
end