Rails display value from lookup table in view - ruby-on-rails

Question

Newbie alert! I hope I can explain my situation accurately and understandably.
I have a model called animals. Another model called statuses. Another called sexes.
From animal.rb model:
class Animal < ActiveRecord::Base
belongs_to :status, :class_name => Status, :foreign_key => :status_id
belongs_to :sex, :class_name => Sex, :foreign_key => :sex_id
end
sex.rb model:
class Sex < ActiveRecord::Base
has_many :animals
end
status.rb model:
class Status < ActiveRecord::Base
has_many :animals
end
In my views/animals/index.html.erb I have this:
<% #animals.each do |animal| %>
<tr>
<td><%= animal.name %></td>
<td><%= animal.eartag %></td>
<td><%= animal.sex.sex %></td>
<td><%= animal.status.status %></td>
...
The column in the table displays the sex from the sexes lookup table fine, but the line for status causes the following error:
NoMethodError in Animals#index
undefined method `status' for nil:NilClass
So I guess Rails is thinking animal.status is nil?? I don't know why it would be when animal.sex is not nil.
Also, I have views/animals/show.html.erb. Part of that is:
<dt><strong><%= model_class.human_attribute_name(:sex_id) %>:</strong></dt>
<dd><%= #animal.sex.sex %></dd>
<dt><strong><%= model_class.human_attribute_name(:status_id) %>:</strong></dt>
<dd><%= #animal.status.status %></dd>
And this works fine. I.e. in the columns for Sex and Status, it displays the values from the sex and status columns of the sex and status tables, respectively, as I want the index.html.erb view to do.
I don't know if it makes any difference, but here's animals_controller.rb:
class AnimalsController < ApplicationController
before_action :set_animal, only: [:show, :edit, :update, :destroy]
# GET /animals
# GET /animals.json
def index
#animals = Animal.all
end
# GET /animals/1
# GET /animals/1.json
def show
end
# GET /animals/new
def new
#animal = Animal.new
end
# GET /animals/1/edit
def edit
end
# POST /animals
# POST /animals.json
def create
#animal = Animal.new(animal_params)
respond_to do |format|
if #animal.save
format.html { redirect_to #animal, notice: 'Animal was successfully created.' }
format.json { render action: 'show', status: :created, location: #animal }
else
format.html { render action: 'new' }
format.json { render json: #animal.errors, status: :unprocessable_entity }
end
end
end
# PATCH/PUT /animals/1
# PATCH/PUT /animals/1.json
def update
respond_to do |format|
if #animal.update(animal_params)
format.html { redirect_to #animal, notice: 'Animal was successfully updated.' }
format.json { head :no_content }
else
format.html { render action: 'edit' }
format.json { render json: #animal.errors, status: :unprocessable_entity }
end
end
end
# DELETE /animals/1
# DELETE /animals/1.json
def destroy
#animal.destroy
respond_to do |format|
format.html { redirect_to animals_url }
format.json { head :no_content }
end
end
private
# Use callbacks to share common setup or constraints between actions.
def set_animal
#animal = Animal.find(params[:id])
end
# Never trust parameters from the scary internet, only allow the white list through.
def animal_params
params.require(:animal).permit(:name, :eartag, :reg_num, :sex_id, :date_birth, :date_acquired, :date_removed, :status_id, :num_horns, :sire_id, :dam_id, :source_id, :origin_id, :percent_black, :percent_lilac, :for_sale, :for_sale_status_id, :quality_id, :sale_price, :to_be_culled, :comments, :comments_web, :show_on_website, :core_flock, :birth_id, :rejected_at_birth)
end
end
I hope this makes some kind of sense. Thanks!

Answer 1

Change this line
<%= animal.status.status %>
to
<%= animal.status.status if animal.status %>
This will prevent the error. Will output animal.status.status only if animal.status is present.