view incorrectly reloads after uniqueness validation error - ruby-on-rails

Question

After you try to submit a new guideline and you see an error message on the form (due to the guidelines correctly failing validation)...the list of #specialties does not reload correctly (ie. it just says yes/no rather than the proper list you could see before you submitted with an error). I can't work out which part is wrong here...
VIEWS _form.html.erb
<%= simple_form_for(#guideline, html: {class: "form-horizontal"}) do |f| %>
<% if #guideline.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#guideline.errors.count, "error") %> prohibited this guideline from being saved:</h2>
<ul>
<% #guideline.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<%= f.input :title, label: 'Title (e.g. Asthma for under 12 months)' %>
<%= f.input :specialty, as: :select, collection: #specialties %>
<%= f.input :hospital %>
<%= f.input :content, as: :string, label: 'Link' %>
<div class="form-actions">
<%= f.button :submit, :class => "btn btn-info btn-large" %>
</div>
<% end %>
guidelines_controller.rb
def new
#guideline = Guideline.new
#specialties = Guideline.order(:specialty).uniq.pluck(:specialty)
respond_to do |format|
format.html # new.html.erb
format.json { render json: #guideline }
end
end
def create
#guideline = current_user.guidelines.new(params[:guideline])
respond_to do |format|
if #guideline.save
format.html { redirect_to #guideline, notice: 'Guideline was successfully created.' }
format.json { render json: #guideline, status: :created, location: #guideline }
else
#specialties = Guideline.order(:specialty).uniq.pluck(:specialty)
format.html { render action: "new" }
format.json { render json: #guideline.errors, status: :unprocessable_entity }
end
end
end

Answer 1

this is a common error. in your create action you should declare #specialties if the validation fails since that is needed in the new template.
def create
#guideline = Guideline.new params[:guideline]
if #guideline.save
else
# you need to declare #specialties here since it is needed in the new template
# which you want to render
#specialties = Specialty.all
render :new
end
end