Multiple non-nested model creation on same page

Create multiple records in one form with one model

Here's users_controller.rb

 def new
 end
 def create_multiple
    params[:users].each do |user|
     user = User.create(user)
    end
    redirect_to users_url
  end

Here's new.html.erb

<%= form_tag '/users/create_multiple' do %>

  <%= render 'user_fields' %>
  <div class="actions">
    <%= submit_tag %>
  </div>
<% end %>

Here's _user_fields.html.erb

<script type="text/javascript">
$(function() {
        var scntDiv = $('#addusers');
        var i = $('#addusers div').size() + 1;

        $('#addfields').on('click', function() {
                $('<div class="field"><h2>User ' + i +'</h2><input id="users__firstname' + i +'" name="users[][firstname]" placeholder="first name" type="text" /><input id="users__lastname' + i +'" name="users[][lastname]" placeholder="last name" type="text" /></div>').appendTo(scntDiv);
                i++;
                return false;
        });


});

</script>
<div id="addusers">
<div class="field">
 <h2>User 1</h2>
 <%= text_field_tag "users[][firstname]", nil, :placeholder => "first name" %>
 <%= text_field_tag "users[][lastname]", nil, :placeholder => "last name" %>
</div>
</div>

<a href="#" id="addfields">Add a New User</a><br/>

Result on Log

Started POST "/users/create_multiple" for 127.0.0.1 at 2013-06-05 00:40:07 +0700

Processing by UsersController#create_multiple as HTML
  Parameters: {"utf8"=>"V", "authenticity_token"=>"xOPM6PB1h6DMUEGS7fX9/eWs/e6dg
XKRj231ReviKFo=", "users"=>[{"firstname"=>"test1", "lastname"=>"last1"}, {"first
name"=>"test2", "lastname"=>"last2"}], "commit"=>"Save changes"}
  ←[1m←[36m (78.0ms)←[0m  ←[1mbegin transaction←[0m
  ←[1m←[35mSQL (49.0ms)←[0m  INSERT INTO "users" ("created_at", "firstname", "la
stname", "updated_at") VALUES (?, ?, ?, ?)  [["created_at", Tue, 04 Jun 2013 17:
40:08 UTC +00:00], ["firstname", "test1"], ["lastname", "last1"], ["updated_at",
 Tue, 04 Jun 2013 17:40:08 UTC +00:00]]
  ←[1m←[36m (7.0ms)←[0m  ←[1mcommit transaction←[0m
  ←[1m←[35m (0.0ms)←[0m  begin transaction
  ←[1m←[36mSQL (3.0ms)←[0m  ←[1mINSERT INTO "users" ("created_at", "firstname",
"lastname", "updated_at") VALUES (?, ?, ?, ?)←[0m  [["created_at", Tue, 04 Jun 2
013 17:40:08 UTC +00:00], ["firstname", "test2"], ["lastname", "last2"], ["updat
ed_at", Tue, 04 Jun 2013 17:40:08 UTC +00:00]]
  ←[1m←[35m (5.0ms)←[0m  commit transaction
Redirected to http://localhost:3000/users
Completed 302 Found in 156ms (ActiveRecord: 142.0ms)

You can add validation code as per your wishes, here's how to pass form params for multiple records basic-structures

Adding fields and keep only one form, one submit button:

= form_tag(url: create_user_path, remote: true) do
  %table
    %tr
      %td= text_field_tag 'user[][first_name]'
      %td= text_field_tag 'user[][last_name]'

    %tr.actions
      %td= submit_tag 'Save'
      %td= button_tag 'Add new user form', id: 'add_user_form'

    %tr.new_user_row.hidden # hidden class matches the css rule: {display:none;}
      %td= text_field_tag "user[][first_name]"
      %td= text_field_tag "user[][last_name]"

:javascript # jQuery
  $('#add_user_form').bind('click', function(e) {
    var row = $('tr.new_user_row').clone().removeClass('hidden new_user_row');
    $('tr.actions').before(row); # will append the <tr> before the actions
  });

In UsersController:

def create
  params[:user].each do |attr|
    User.create(attr)
  end
end

---

The row tr.new_user_row.hidden serves the purpose of template for a new line: by clicking on the button #add_user_form, the JS code will select the template row, clone it and add this new row with empty inputs as the last visible row of the table.