如何通过Rails中的简单表单设置相关记录？

Question

我无法理解我如何能够改变用户的基本技能，在日志中没有错！ 我正确地建立了accepts_nested_attributes_for？

class User < ApplicationRecord
  has_many :user_skills
  has_many :skills, through: :user_skills

  accepts_nested_attributes_for :user_skills
  accepts_nested_attributes_for :skills

  def primary_skill
    skills.find_by(user_skills: { primary: true })
  end
end

class Skill < ApplicationRecord
  validates :title, presence: true, uniqueness: true

  has_many :user_skills
  has_many :users, through: :user_skills
end

class UserSkill < ApplicationRecord
  belongs_to :skill
  belongs_to :user

  accepts_nested_attributes_for :skill
  accepts_nested_attributes_for :user
end

什么应该是变革的形式

= simple_form_for @user, url: dashboard_user_url, method: :put do |f|
  = f.input :primary_skill, collection: Skill.all, include_blank: false
  = f.submit