Storing List item details in a database? - ruby-on-rails

Question

So, this may be more of a "Software Engineering" question. But im thinking of a good way at how to store details for a Widget in active record.
Pretend Widget A has a show page, and in that show page we have some accordian style "FAQS" or something to that effect. Within the accordian is a list, with bullet points highlighting different things of how Widget A works, or how to use Widget A.
Since obviously we wouldn't want to make a separate page for each widget, these items would need to be stored somewhere. But we also wouldn't want to make...10, 20 or 30 separate fields in the database for each one of these. So whats the solutions for this?
My first thought is some sort of hash or array, but does rails allow this? Especially if they are long strings per item. Is there a better way?
Or is the proper way to do this is just claim this as a model (like.."faq_item") or something, and then have a reference ID for the Widget it needs to go to? (that way the "faq_item" model/schema would only need a few fields, and can just assigned the reference ID to the Widget it would belong to.

Answer 1

If each widget has only a few "FAQ items" (or "details", as I'll refer to them) and each detail is nothing more than a text string, you could store a widget's details in a serialized array as such:
# models/widget.rb
class Widget < ApplicationRecord
# serialize the `details` attribute as JSON into
# the `details` column on the widgets table
serialize :details, JSON
end
# db/schema.rb
# ...
create_table "widgets", force: :cascade do |t|
t.string "name"
t.text "details"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
# rails console
wid = Widget.create!(
:name =>
'Wideband, Voltage-Feedback Operational Amplifier With Disable',
:details => [
'Flexible supply range: 5-V to 12-V Single Supply, +/- 2.5-V to 5-V Dual Supply',
'Unity-Gain Stable: 500 MHz (G = 1)',
'High Output Current: 190 mA',
'High Slew Rate: 1800 V/us',
'Wideband 5-V Operation: 220 MHz (G = 2)'
])
# => #<Widget ...>
wid.details.first
# => "Flexible supply range: 5-V to 12-V Single Supply, +/- 2.5-V to 5-V Dual Supply"
You can look at the Rails 5 serialization API for more information on serialize.
If, however, you need to store more information for each detail (for instance, created_at/updated_at fields) or each widget has more than a few details, then it may be prudent to create a new table for widget details as you suggested:
# models/widget.rb
class Widget < ApplicationRecord
has_many :details, :dependent => :destroy
end
# models/widget/detail.rb
class Widget::Detail < ApplicationRecord
belongs_to :widget
end
# db/schema.rb
# ...
create_table "widget_details", force: :cascade do |t|
t.integer "widget_id"
t.text "content"
t.datetime "created_at", null: false
t.datetime "updated_at", null: false
end
wid = Widget.create!(
:name =>
'CMOS, 125 MHz Complete DDS Synthesizer',
:details => [
Widget::Detail.create!(:content => '125 MHz Clock Rate'),
Widget::Detail.create!(:content => 'On-Chip High Performance DAC'),
Widget::Detail.create!(:content => '32-Bit Frequency Tuning Word')
])
# => #<Widget ...>
wid.details.first
# => #<Widget::Detail ... content: "125 MHz Clock Rate" ...>

Answer 2

If you are using Postgres you could use a JSONB type field in your database. With a JSONB data type you will be able to have unstructured data while being able to query the field with Postgres and ActiveRecord without the need for a new table.
Like this:
rails g migration add_fields_to_widgets details:jsonb
rails db:migrate
Test your widget creation inside the rails console.
Widget.create(name: "Widget Foo", details: { "how to use": "Instructions on how to use", "height": "12cm", "width": "100cm" })
If you'd want to find all the widgets with 12cm height, you would just have to make a query like this:
Widget.where("details->>'height' = ?", "12cm")
which would return your original Widget Foo object, and then you would be able to manipulate it with pure JavaScript on your front-end.