Error is not showing using different controller - ruby-on-rails

Question

In my task show page, I have form for creating a response and the responses are displayed here as well. (Task has many responses)
views\tasks\show.html.erb
<%= simple_form_for([#task, Response.new]) do |f| %>
<%= f.input :is_comment, as: :hidden %>
<%= f.input :negotiate_pay, label: false %>
<%= f.input :comment_text, as: :text, input_html: {rows: 3}, label: false %>
<div class="row">
<div class="col-md-4 col-md-offset-8">
<%= f.button :submit %>
</div>
</div>
</div>
<% end %>
<br>
<div id="comments">
<%= render #responses %>
</div>
controllers\tasks_controller
def show
#task = Task.find(params[:id])
#responses = #task.responses.all
end
controllers\responses_controller
def create
#task = Task.find(params[:task_id])
#response = #task.responses.create(response_params)
#response.user_id = current_user.id
#response.is_comment = params[:is_comment]
#response.save
respond_to do |format|
format.html { redirect_to #task }
format.js
end
end
It is working alright but it doesn't show the errors in the form after validation and submit. How can I show the error message in response form which is in the show page of task. I am using a simple_form btw.
Help please
EDIT:
Models:
models\response.rb
belongs_to :user
belongs_to :task
has_many :subcomments
default_scope -> { order('created_at DESC') }
#VALIDATIONS
validates :comment_text, presence: true
validates :negotiate_pay, presence: true

Answer 1

You need to add the code that will display the errors to your form :
<%= simple_form_for([#task, Response.new]) do |f| %>
<% if #response.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#response.errors.count, "error") %> prohibited this response from being saved:</h2>
<ul>
<% #response.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
and you also need to tweak your create action in the responsesController:
def create
#task = Task.find(params[:task_id])
#response = #task.responses.build(response_params)
#response.user_id = current_user.id
#response.is_comment = params[:is_comment]
respond_to do |format|
if #response.save
format.html { redirect_to #task, notice: "response was createad" }
format.js
else
format.html { render :show }
end
end
also make sure you are displaying the errors inside your application.html.erb :
<% if flash[:error] -%>
<p class='alert alert-danger'><%=h flash[:error] %></p>
<% end -%>
<% if flash[:notice] -%>
<p class='alert alert-success'><%=h flash[:notice] %></p>
<% end -%>