undefined method `hirahana_value' for nil:NilClass - ruby-on-rails

Question

I try to understand what my buddy has coded to call in a show#view some instance variable. I have a problem to understand his code and call the method hirahana_value.
Here is my controller
class SymbolesController < ApplicationController
before_action :set_symbole, only: [:show, :edit, :update, :destroy, :load_form, :load_attributes_form]
def index
#symboles = Symbole.all
end
def show
end
def new
#symbole = Symbole.new
end
def edit
end
def create
#symbole = Symbole.new()
if symbole_params[:symbole_type].present?
#symbole.build_kanji_attribute if symbole_params[:symbole_type] == "kanji"
#symbole.build_hiragana_and_katagana_attribute if symbole_params[:symbole_type] == "hiragana_and_katagana"
end
#symbole.assign_attributes(symbole_params)
respond_to do |format|
if #symbole.save
format.html { redirect_to #symbole, notice: 'Symbole was successfully created.' }
format.json { render :show, status: :created, location: #symbole }
else
format.html { render :new }
format.json { render json: #symbole.errors, status: :unprocessable_entity }
end
end
end
def update
respond_to do |format|
if #symbole.update(symbole_params)
format.html { redirect_to #symbole, notice: 'Symbole was successfully updated.' }
format.json { render :show, status: :ok, location: #symbole }
else
format.html { render :edit }
format.json { render json: #symbole.errors, status: :unprocessable_entity }
end
end
end
def destroy
#symbole.destroy
respond_to do |format|
format.html { redirect_to symboles_url, notice: 'Symbole was successfully destroyed.' }
format.json { head :no_content }
end
end
def load_form
#symbole = Symbole.new if #symbole.nil?
if params[:form_name].present?
respond_to do |format|
format.js { render "ajax_form_"+params[:form_name] }
end
end
end
def load_attributes_form
#symbole = Symbole.new if #symbole.nil?
if params[:form_name].present?
respond_to do |format|
format.js { render "ajax_form_"+params[:form_name] }
end
end
end
private
def set_symbole
if params[:id].present?
#symbole = Symbole.find(params[:id])
else
#symbole = Symbole.new
end
end
def symbole_params
params.require(:symbole).permit(:lang, :example_fr, :symbole_type, :css_class, kanji_attribute_attributes: [:value,:concept, :fr],
hiragana_and_katagana_attribute_attributes: [:hirahana_value,:katagana_value, :fr]
)
end
end
And here is the new#view to create my object
<%= simple_form_for #symbole, :defaults => {:required => true} do |f| %>
<%= f.error_notification %>
<div class="form-inputs">
<%= f.hidden_field :lang, value: "Japonais"%>
<%= f.select :symbole_type, options_for_select([["Kanji", "kanji"], ["Hiragana/Katagana", "hiragana_and_katagana"]]) , {:prompt => "Type de symbole", selected: #symbole.symbole_type}, {required: true} %>
<div id="specific_attributes">
</div>
<%= f.input :example_fr, placeholder: "Exemple", label: "Exemple" %>
<%= f.input :css_class, placeholder: "Nom de la classe css" , label: "Classe"%>
</div>
<div class="form-actions">
<%= f.button :submit, "Valider" %>
</div>
<% end %>
here is the show#view, I just want to call
<ul class="list-inline text-center card-frame">
<li>
<div class="card">
<div class="front">
<!-- PARAMETRER LE RESPONSIVE BOOTSTRAP -->
<!-- <div class="col-sm- col-xs-4 col-md-3"> -->
<div class="card-hiragana hiragana-<%=#hiragana_and_katagana_attributes.hirahana_value.downcase.last%>">
<h1><b><%= #hiragana_and_katagana_attributes.hirahana_value %></b></h1>
</div>
<div class="card-katakana">
<p><%= #hiragana_and_katagana_attributes.hirahana_value %></p>
</div>
<!-- </div> -->
</div>
<div class="back">
<div class="col-sm-3 col-xs-4 col-md-3 containerbackcards-<%=#hiragana_and_katagana_attributes.hirahana_value.downcase.last%>">
<div class="backcard-hiragana">
<h1><b><%= #hiragana_and_katagana_attributes.hirahana_value %></b></h1>
</div>
<div class="card-bigletter">
<p><%= #hiragana_and_katagana_attributes.hirahana_value %></p>
</div>
</div>
</div>
</div>
</li>
</ul>
<div class="text-center buttons-view-post">
<% if current_user.try(:admin?) %>
<%= link_to "Modifier l'hiragana", edit_hiragana_path(#hiragana), class: "btn btn-default btn-md" %>
<% end %>
<%= link_to "Voir tous les hiraganas", hiraganas_path, class: "btn btn-default btn-md" %>
</div>
</div>
</div>
</div>
</div>

Answer 1

The controller instance variable #hiragana_and_katagana_attributes has not been given a value within the context of the #show action, at least not in a way that's immediately visible. Wherever you are expecting this object to get instantiated, that's not happening.