Masatoshi Nishiguchi
Software Engineer

Adding Ajax to forms in Rails

rails ajax

This is my memo on Adding Ajax to forms in Rails.

Adding Ajax to web forms is a common practice so Rails makes Ajax easy to implement.

HTML

Add remote: true option to form_for method then Rails automagically uses Ajax.

app/views/household_items/index.html.slim

using form_tag

...
- moving.tags.each do |tag|
  = form_tag(moving_household_items_path, method: :get, remote: true) do
    = hidden_field_tag :filter, tag.name
    = submit_tag tag.name.capitalize, name: nil
...

or using link_to

...
- moving.tags.each do |tag|
  = link_to tag.name, moving_household_items_path(filter: tag.name),
    method: :get, remote: true, class: "btn btn-xs btn-info"
...

Controller

Use respond_to method to handle both html and js formats.

app/controllers/household_items_controller.rb

def index
  respond_to do |format|
    format.html do
      @household_items = @moving.household_items
      render :index
    end
    format.js do
      if params[:filter].present?
        @household_items = HouseholdItem.tagged_with(params[:filter], params[:moving_id])
      else
        @household_items = @moving.household_items
      end
    end
  end
end

JS

Replace the content by rendering a partial.

app/views/household_items/index.js.erb

/*
When a filter button is clicked, the following script is invoked via household_items#index action.
It replaces the table content with filtered data.
 */
$(document).ready(function () {
  $('#moving_items').html(
    "<%= escape_javascript(render 'shared/moving_items', moving: @moving, household_items: @household_items) %>"
  );
});

References