How can i add into database column array from ruby on rails model?

i have to following method

before_save :save_each_item_details

def save_each_item_details
  items = itemname.length
  i = 0

  while i < items
    items = itemname.length
    if !ItemsCensu.exists?(itname: itemname[i], year: "#{date.to_s.split('-').first}")
      ItemsCensu.create(itname: itemname[i], monadaM: mm[i], quntity: quantity[i], price: price[i], tax: tax[i], year: "#{date.to_s.split('-').first}", num_invoice << invoice_num)
      i += 1
    else
      puts "test"
      i += 1
    end
  end
end

num_invoice is the array from database. invoice_num is a number like 1239

Each time I save it, I want it to to add the invoice_num into num_invoice[] without removing the old value.

For example

1st save:

invoice_num = 1234
num_invoice << invoice_num
# => 1234

2nd save:

invoice_num = 12345
num_invoice << invoice_num
# => [1234, 12345]

Is there a way to build this into my ItemsCensu.create, something like ItemsCensu.create(num_invoice: << invoice_num)?