Ruby on rails 创建新记录会自动用类名填充类型列

我是rails新手，正在研究我在文件task.rb中看到的继承代码，如下所示：

class Task < ApplicationRecord

  include ActiveRecord::UnionScope

  default_scope { where.not(status: 'Canceled') }
  scope :done, -> { where(status: 'Done').order(id: :desc) }
  scope :pending, -> { where(status: 'Pending').order(id: :desc) }
  scope :in_progress, -> { where.not(status: 'Done').order(id: :asc) }

  def type_human_readable
    self.class.to_s
  end

end

class SwitchDbConfigFiles < Task
  def type_human_readable
    'Switch Database Configuration Files'
  end
end

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问题是：究竟是如何（根据什么规则）为type列分配模型类名的？

在我看来，这与ActiveRecord类似。默认情况下，

type

属性用于此目的，因此会自动设置

class ApplicationRecord < ActiveRecord::Base
  self.abstract_class = true
end

  create_table "tasks", id: :integer, force: :cascade, options: "ENGINE=InnoDB DEFAULT CHARSET=utf8" do |t|
    t.datetime "created_at"
    t.datetime "updated_at"
    t.string "type"
    t.date "date"
    t.text "message"
    t.string "status", default: "Pending", null: false
    t.text "data"
    t.index ["date", "status", "type"], name: "last_task_of_type_3"
    t.index ["date", "type", "status"], name: "last_task_of_type_2"
    t.index ["type", "status", "date"], name: "last_task_of_type"
  end