How to make ajax call and show error messages - ruby-on-rails

Question

Two of the action of My registration controller is new and create.
def new
#regist = Regist.new
respond_to do |format|
format.html # new.html.erb
format.json { render json: #regist }
end
end
def create
#regist = Regist.new(regist_params)
respond_to do |format|
if #regist.save
format.html { redirect_to #regist, notice: 'Regist was successfully created.' }
format.json { render json: #regist, status: :created, location: #regist }
else
format.html { render action: "new" }
format.json { render json: #regist.errors, status: :unprocessable_entity }
end
end
end
And the new form contain following code.
<%= form_for(#regist) do |f| %>
<% if #regist.errors.any? %>
<div id="error_explanation">
<h2><%= pluralize(#regist.errors.count, "error") %> prohibited this regist from being saved:</h2>
<ul>
<% #regist.errors.full_messages.each do |msg| %>
<li><%= msg %></li>
<% end %>
</ul>
</div>
<% end %>
<div class="field">
<%= f.collection_select :student_id, Student.all, :id, :name %><br />
</div>
<div class="field">
<%= f.collection_select :semester_id, Semester.all, :id, :name %><br />
</div>
<div class="field">
<% for subject in Subject.find(:all) %>
<%= check_box_tag "regist[subject_ids][]", subject.id %>
<%= subject.name %><br>
<% end %>
</div>
<div class="field">
<%= f.label :date_of_birth %><br />
<%= f.text_field :date_of_birth %>
</div>
<div class="actions">
<%= f.submit %>
</div>
<% end %>
Now, when someone click on submit button I want to make ajax call using remote true if there are validation errors and show the errors without reloading the page. And if there are no validation errors I want the user to be redirected to show page. How can I do this?

Answer 1

First of all you should add a remote: true to your existing form to allow remote action.
TODO this just add on the first line of your form the remote: true,
<%= form_for(#regist, remote: true) do |f| %>
the rest leave it as it is. Then you need to make your controller to respond to remote calls, therefore you need to alter the responds_to block of create action:
respond_to do |format|
if #regist.save
format.html { redirect_to #regist, notice: 'Regist was successfully created.' }
format.json { render json: #regist, status: :created, location: #regist }
format.js { render js: "window.location.href='"+regists_path+"'"}
else
format.html { render action: "new" }
format.json { render json: #regist.errors, status: :unprocessable_entity }
format.js
end
end
The last step you have to do is to add a file to your app/views/regists/ directory
where you should add a create.js.erb file:
<% if #regist.errors.any? %>
$('#new_regist').effect('highlight', { color: '#FF0000'}, 1000); // for highlighting
// or add here whatever jquery response you want to have to your views.
<% end %>
You will get your validation errors displayed like before above the form.
You have to add the redirect to your controller to the desirable action of your choice. I have added for you a window.location.href as a response to the regists_path.