factory-bot/factory-girl添加所属对象的语法

我有以下型号:

class SecondaryIabCategory < ApplicationRecord
  has_many :sites, foreign_key: :secondary_category_id
  belongs_to :primary_iab_category
end

并对以下工厂的问题进行了评论:

  factory :primary_category, class: PrimaryIabCategory do
    name 'Arts & Entertainment - yaddah'
    value 'IAB1-some'
  end

  factory :another_primary_category, class: PrimaryIabCategory do
    name 'Games are cool! - dabbah'
    value 'IAB1-other'
  end

  factory :secondary_category, class:  SecondaryIabCategory do
    # here is the problem - what's the correct syntax?
    primary_iab_category another_primary_category
    name 'Test Secondary Cat'
    value 'xxyy'
  end

我得到错误消息:

NoMethodError: undefined method `another_primary_category=' for #<SecondaryIabCategory:0x00007f925c64e0d8>

我已经有几个月没有使用factrybot/girl了,所以不知道它的语法是什么。有什么想法吗?