[RUBY] I tried to explain Active Hash

ActiveHash By directly describing the unchanged data such as occupation selection in the model file, the data can be handled without saving it in the database. In other words, by using Active_Hash, ActiveRecord methods can be used for the unchanged data described directly in the model file.

Introduction method

Gemfile

`qiita.rb`


gem 'active_hash'

After writing, execute bundle install.

Things to keep in mind when creating a model

In conclusion, use --skip-migration. The reason is not to create a database. That is, the migration file is no longer needed. Note that if you use the rails g model command here, a migration file will be created at the same time.

%rails g model model name--skip-migration

ActiveHash::Base You can use the same methods as ActiveRecord. In other words, by inheriting ActiveHash :: Base, ActiveRecord methods can be used for the objects defined in the model.

`qiita.rb`


class ShippingFee < ActiveHash::Base
  self.data = [
    { id: 0, name: '---' },
    { id: 1, name: 'Cash on delivery(Buyer burden)' }, { id: 2, name: 'postage included(Exhibitor burden)' }
  ]
end

Image of creating a table with self.data. The data is stored in an array in hash format.

belongs_to_active_hash Normally, it will be belongs_to: model name, but if you want to set an association for a model created using ActiveHash, use belongs_to_active_hash method.

collection_select Method that can display data in pull-down format

Description order	Details	Concrete example
First argument	Method name	Column name
Second argument	object	Specification of array data
Third argument	id	Reference DB column name
Fourth argument	name	Actual column name
Fifth argument	prompt	What you want to display at the top of the pull-down
option	name of the class	--

`qiita.rb`


<%= f.collection_select(:shipping_fee_id, Shipping_fee.all, :id, :name, {}, {class:"select-box", id:"item-shipping-fee-status"}) %>

Implementation example

I've listed some typical ones ·Prefectures ・ Occupation selection ・ Closed question (like answering yes or no) ·questionnaire ・ Category ・ Product status

Personally, I felt that this would greatly reduce the stress on the user side and that it would be possible to collect information efficiently. It may be good to use it when you want to ask the other party for their opinions.

Finally

Thank you for reading the article so far.

ActiveHash is also incorporated into things that you use casually. It's easy to implement, so I wanted to use it positively.

I would like to continue to provide useful information as I continue to study, so I look forward to working with you.

Thank you very much for reading the article so far!