具有`has_one`关联时的Rails `form_with`

# app/models/user.rb
class User < ApplicationRecord
  has_one :profile
  accepts_nested_attributes_for :profile
end

# app/models/profile.rb
class Profile < ApplicationRecord
  belongs_to :user
end

# app/controllers/users_controller.rb
class UsersController < ApplicationController
  def new
    @user = User.new
    @user.build_profile
  end

  def create
    @user = User.new(user_params)
    if @user.save
      # 保存成功的处理逻辑
    else
      # 保存失败的处理逻辑
    end
  end

  private

  def user_params
    params.require(:user).permit(:name, profile_attributes: [:age, :gender])
  end
end

# app/views/users/new.html.erb
<%= form_with(model: @user, local: true) do |form| %>
  <%= form.label :name %>
  <%= form.text_field :name %>

  <%= form.fields_for :profile do |profile_form| %>
    <%= profile_form.label :age %>
    <%= profile_form.text_field :age %>

    <%= profile_form.label :gender %>
    <%= profile_form.text_field :gender %>
  <% end %>

  <%= form.submit %>
<% end %>