Rails Admin: too many dropdown entries - ruby-on-rails

Question

in my rails_admin application, I have a table "Branch" that references another table called "Alarms". In "Branches", I'd like to select exactly one alarm and have a search box to search these alarms.
Currently, I'm only capable to create a drop down with all alarms related to that branch which causes many entries to be rendered (over 25k) and memory to be consumed.
I couldn't find an example how to create a dropdown that says "too many entries, search to select", similar to the has_and_belongs_to_many.
Here's how it looks:
class Branch < ApplicationRecord
...
# this is fine and works as expected, selecting only the first (and only) entry
show do
field :maintenance_period_trigger_alarm_id do
formatted_value do
alarm = Alarm.where(id: bindings[:object].maintenance_period_trigger_alarm_id).first
path = bindings[:view].show_path(model_name: 'alarm', id: alarm.id)
bindings[:view].link_to(alarm.name, path)
end
end
end
...
# this is where all elements are automatically loaded and rendered in the dropdown
edit do
field :maintenance_period_trigger_alarm_id, :enum do
enum do
Alarm.where(branch_id: bindings[:controller].params[:id]).collect{ |alarm| [alarm.name, alarm.id] }
end
end
end
I'm not sure how I can enable a simple "Too many entries" message to not show 25k entries in there.

Answer 1

#zokkker13, here is a very basic fleshed-out example that will query a people_controller.rb for people by name.
Add select2 to your page
Either download select2.js and select2.css, put them into your vendor folder and add them to your applications.js and application.css files, or just
include them from a CDN into your page. Load your page and use your browser's dev tools to make sure that select2.js is loaded.
Add a new route to config/routes.rb
resources :people do
collection do
get 'search'
end
end
Restart your server.
Add search action to people_controller.rb
# coding: utf-8
class PeopleController < ApplicationController
def search
# https://select2.org/data-sources/ajax
term = params[:term]
matches = Person.where("name ILIKE ?", "%#{term}%").to_a
# https://select2.org/data-sources/formats
matches.map!{ |m| { id: m.id, text: m.name } }
respond_to do |format|
format.json {
render status: 200, json: { results: matches }
}
end
end
end
Add search box to page
Add this to your html page:
<%= select_tag :search, nil, id: 'select2-live-search-people' %>
<script>
$(document).ready( function() {
$('#select2-live-search-people').select2({
ajax: { url: '/people/search', dataType: 'json' },
placeholder: 'Start typing to search...',
width: '300px',
minimumInputLength: 3
});
} );
</script>
.. or this, if you use haml:
= select_tag :search, nil, id: 'select2-live-search-people'
:javascript
$(document).ready( function() {
$('#select2-live-search-people').select2({
ajax: { url: '/people/search', dataType: 'json' },
placeholder: 'Start typing to search...',
width: '300px',
minimumInputLength: 3
});
} );
Modify the code so that it will query an existing model w/ existing data. Then relaod the page and start typing. You should now see the select option getting adjusted to the result of your search term. Use the minimumInputLength parameter to control how many characters are minimally needed to issue an ajax call. With potentially 25k options, you might want to increase it even more.