ActiveAdminComplexNestedForm.rb

= semantic_nested_form_for [:admin, @project] do |f|
  = f.inputs "Project Details" do
    = f.input :start_date, as: :date_picker
    = f.input :doc_name
    = f.input :project_name
    = f.input :end_date, as: :date_picker
    = f.input :company_id, as: :select, collection: Company.all.map {|c| [c.company_name, c.id]}
    = f.input :working_estimate_id, as: :check_boxes, collection: WorkingEstimate.all.map {|c| [c.working_title, c.id]}
  
    br
    br
    = f.inputs 'Working Estimates' do
      = f.semantic_fields_for :working_estimates do |we|
        = we.input :working_title   
        = we.input :sub_workings, as: :check_boxes, collection: SubWorking.all.map { |s| [s.sub_working_title, s.id] }
        br
        br
        = we.inputs 'Sub Workings' do
          = we.semantic_fields_for :sub_workings do |sw|
            = sw.input :sub_working_title
            = sw.input :working_hour
            = sw.input :specialists, as: :check_boxes, collection: Specialist.all.map { |s| [s.sub_working_title, s.id] }
          
            br
            br
            = sw.inputs 'Specialist' do
              = sw.semantic_fields_for :specialists do |s|
                = s.inout :name
                = s.input :rate
      
    
  = f.actions do
    = f.action :submit
    = f.action :cancel

# How to setup params for this :)
permit_params :start_date, :end_date, :doc_name, :project_name, :company_id,
                working_estimates_attributes: [:id, :working_title, :_update, :_destroy, sub_working_ids: [],
                sub_workings_attributes: [:id, :sub_working_title, :working_hour, specialist_ids: [],
                specialist_attributes: [:id, :name, :rate] ]]