Using model constants as groups in Rails grouped_collection_select - ruby-on-rails

Question

I'm building a form where users create a financial transaction. One field is a drop down list of bank accounts.
I would like this dropdown list to group all listed Bank Accounts by each account's account type (BankAccount::ACCOUNT_TYPE - an attribute in each BankAccount record).
If I manually code everything right now, the code would look like this:
<%= f.select :bank_account_id,
{
'On-Budget' => ['Cash',
'Credit Card 1',
'Credit Card 2',
'Venmo'],
'Off-Budget' => ['Investment Bank 1',
'Investment Bank 1'],
'Closed' => ['Old Bank 1',
'Old Bank 2'],
} %>
app/models/bank_account.rb - where I define ACCOUNT_TYPES
class BankAccount < ApplicationRecord
ACCOUNT_TYPES = %w(On-Budget Off-Budget Closed).freeze
...
end
Here is my working collection.select, without grouping
<%= f.collection_select :bank_account_id,
BankAccount.all,
:id,
:name,
{prompt: 'Select an account'} %>
From the rails API, I think grouped_collection_select is what I need
(https://api.rubyonrails.org/classes/ActionView/Helpers/FormBuilder.html#method-i-grouped_collection_select)
grouped_collection_select(method, collection, group_method, group_label_method, option_key_method, option_value_method, options = {}, html_options = {})
Using BankAccount::ACCOUNT_TYPES as my group_method, and group_label_method doesn't work.
<%= f.grouped_collection_select(:bank_account_id,
BankAccount.all,
BankAccount::ACCOUNT_TYPES, (group_method?)
BankAccount::ACCOUNT_TYPEs, (group_label_method?)
:id,
:name,
{prompt: 'Select an account' } %>

Answer 1

I found the answer from this SO question: https://stackoverflow.com/questions/36854817/use-grouped-collection-select-to-group-a-model-by-enum
I created a helper method
def grouped_bank_account_options_for_select(selected_bank_account_id = nil)
options = {}
BankAccount::ACCOUNT_TYPES.each do |t|
unless t == "Closed"
options[t] = BankAccount.where(account_type: t)
.pluck(:name, :id)
end
end
grouped_options_for_select(options, selected_bank_account_id)
end
and then called it in the view's form helper
<%= select_tag :bank_account_id, grouped_bank_account_options_for_select(params[:bank_account_id]), {prompt: 'Select an account'} %>