Custom view for rails_admin to create related HABTM records

_custom_multiselect.html.haml

:ruby
  config = field.associated_model_config
  selected = field.bindings[:object].send(field.association[:name])
  selected_ids = selected.map(&:id)
  xhr = field.associated_collection_count > 100
  if xhr
    collection = selected.map do |o|
      [o.send(config.object_label_method), o.id]
    end
  else
    collection = field.associated_collection(@authorization_adapter).sort_by {|a| selected_ids.index(a[1]) || selected_ids.size }
  end

= field_wrapper_for(form, field) do
  %input{:name => field.dom_name, :type => "hidden", :value => ""}
  = form.select field.method_name, collection, { :selected => selected_ids, :object => @object }, field.html_attributes

- head_style 'rails_admin/ra.filtering-multiselect.css'
- head_javascript "rails_admin/ra.filtering-multiselect.js"
- head_javascript "ms.remote-form.js"
- head_javascript do
  $j(document).ready(function($){
  $("##{field.dom_id}").filteringMultiselect({
  - if xhr
    createQuery: function(query) {
    return { query: query }
    },
    source: "#{rails_admin_list_path(config.abstract_model.to_param, :compact => true)}",
  sortable: #{field.orderable ? 'true' : 'false'},
  regional: {
  chooseAll: "#{t("admin.new.chose_all")}",
  chosen: "#{t("admin.new.chosen", :name => config.abstract_model.model.model_name.human(:count => 2, :default => config.label.pluralize))}",
  clearAll:  "#{t("admin.new.clear_all")}",
  selectChoice: "#{t("admin.new.select_choice")}",
  up: "#{t("admin.new.up")}",
  down: "#{t("admin.new.down")}"
  }
  });
  $(".#{field.dom_id} .hasAndBelongsToManyAssociation").after('#{link_to t('admin.actions.create').capitalize + ' ' + config.abstract_model.pretty_name.downcase, rails_admin_new_path(:model_name => config.abstract_model.to_param), :class => "createAssociatedRecord"}');
  $(".#{field.dom_id} .createAssociatedRecord").remoteForm({ dialogClass: "createAssociatedRecordDialog" });
  });

ms.remote-form.js

(function($) {
    $.extend($.ra.remoteForm.prototype, {
        _bindFormEvents: function() {
            var dialog = this._getDialog(),
            form = dialog.find("form"),
            widget = this,
            saveButtonText = dialog.find(":submit[name=_save]").text(),
            cancelButtonText = dialog.find(":submit[name=_continue]").text();

            dialog.dialog("option", "title", $("h2.title", dialog).remove().text());

            form.attr("data-remote", true);
            dialog.find(":submit").remove();
            dialog.find(".ra-block-content").removeClass("ra-block-content");

            var buttons = {};

            if (saveButtonText) {
                buttons[saveButtonText] = function() {
                    // We need to manually update CKeditor mapped textarea before ajax submit
                    if(typeof CKEDITOR != 'undefined') {
                        for ( instance in CKEDITOR.instances )
                            CKEDITOR.instances[instance].updateElement();
                    }
                    dialog.find("form").submit();
                };
            }

            if (cancelButtonText) {
                buttons[cancelButtonText] = function() {
                    dialog.dialog("close");
                };
            }

            dialog.dialog("option", "buttons", buttons);

            /* Remove original button container if it's now empty */
            if (0 == $("form > .navform :submit", dialog).length) {
                $("form > .navform", dialog).remove();
            }

            form.bind("ajax:success", function(e, data, status, xhr) {
                var json = $.parseJSON(data);
                var select = widget.element.siblings('.ra-multiselect').find('.ra-multiselect-right select.ra-multiselect-selection');
                var input = widget.element.siblings('.hasAndBelongsToManyAssociation');
                
                if(select.length > 0) {
                    select.append('<option value="' + json.id + '">' + json.label + '</option>' );
                }
                
                if(input.length > 0){
                    input.append('<option value="' + json.id + '" selected="selected">' + json.label + '</option>' );
                }
                dialog.dialog("close");
            });

            form.bind("ajax:error", function(e, xhr, status, error) {
                dialog.html(xhr.responseText);
                widget._bindFormEvents();
            });
        }
    });
})(jQuery);

rails_admin.rb

RailsAdmin.config do |config|
  config.model Content do
    edit do
      field :tags, :has_and_belongs_to_many_association do
        partial 'custom_multiselect'
      end
    end
  end
end